Hydraulics & Pneumatics - Hydraulics & Pneumatics is the leading international technical resource for fluid power http://hydraulicspneumatics.com/rss.xml en Compressed Air Guide: Pull, Don’t Push http://hydraulicspneumatics.com/air-compressors/compressed-air-guide-pull-don-t-push <div class="field-byline"> Staff </div> <div class="field-deck"> Vacuum uses the surrounding atmosphere to create work force by pulling on, rather than pushing, a work piece. </div> <div class="node-body article-body"><p>Evacuating air from a closed volume develops a pressure differential between the volume and the surrounding atmosphere. If this closed volume is bound by the surface of a vacuum cup and a work piece, atmospheric pressure will press the two objects together. The amount of holding force depends on the surface area shared by the two objects, and the vacuum level. In an industrial vacuum system, a pump or generator removes air from a system to create a pressure differential.</p> <p>Because it&rsquo;s impossible to remove all air molecules from a container, a perfect vacuum cannot be achieved. Of course, removing more air increases the pressure differential and strengthens the potential vacuum force.</p> <div class="related-content"> <div class="related-label"> Related</div> <p><a href="/air-compressors/air-tank">Air in the Tank</a></p> <p><a href="/air-compressors/compressed-air-may-be-more-efficient-you-think">Compressed Air May Be More Efficient Than You Think</a></p> <p><a href="/air-compressors/raising-bar-compressor-efficiency">Raising the Bar on Compressor Efficiency</a></p> </div> <p>The pressure differential between the evacuated volume and surrounding atmosphere determines vacuum level. Several units of measure can be used&mdash;for instance, most refer to the height of a column of mercury, usually in inches of mercury (in.-Hg) or millimeters of mercury (mm-Hg). The common metric unit for vacuum measurement is the millibar, or mbar. Other pressure units sometimes used to express vacuum include the interrelated units of atmospheres, or &ldquo;torr,&rdquo; and microns.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/12/PullDontPush_Fig1_0.jpg" style="width: 300px; height: 377px; float: left;" title="1. Atmospheric pressure force determines the height of a mercury column in a simple barometer." />One standard atmosphere equals roughly 14.7 psi (29.92 in.-Hg). Any fraction of an atmosphere is a partial vacuum and equates with negative gauge pressure. A torr, defined as 1/760 of an atmosphere, can also be thought of as 1 mm-Hg, where 760 mm-Hg equals 29.92 in.-Hg. Even smaller is the micron, defined as 0.001 torr. However, these units are used most often when dealing with near-perfect vacuums, usually under laboratory conditions, and seldom in fluid-power applications.</p> <p>Atmospheric pressure is measured with a barometer. A barometer consists of an evacuated vertical tube with its top end closed and bottom end resting in a container of mercury that&rsquo;s open to the atmosphere. The pressure exerted by the atmosphere acts on the exposed surface of the liquid to force mercury up into the tube. Sea-level atmospheric pressure will support a mercury column generally not more than 29.92 in. high. Thus, the standard for atmospheric pressure at sea level is 29.92 in.-Hg, which translates to an absolute pressure (psia) of 14.69 psia.</p> <p>The two basic reference points in all of these measurements are <em>standard atmospheric pressure</em> and a <em>perfect vacuum</em>. At atmospheric pressure, the value 0 in.-Hg equals roughly14.7 psia. At the opposite reference point, 0 psia, otherwise known as a perfect vacuum (if it could be attained), would have a value equal to the other extreme of its range, 29.92 in.-Hg. However, calculating work forces or changes in vacuum-system volume requires conversions to psia or negative gauge pressure (psig).</p> <table border="0" cellpadding="0" cellspacing="0" width="570"> <tbody> <tr> <td width="41"> <img src="http://insidepenton.com/electronic_design/adobe-pdf-logo-tiny.png" /></td> <td style="padding-left: 0px;" width="459"> <a href="/datasheet/compressed-air-guide-pull-don-t-push-pdf-download">Download this article in .PDF format</a><br /> This file type includes high resolution graphics and schematics when applicable.</td> </tr> </tbody> </table> <p>Most pressure-gauge dials assign the value of zero to atmospheric pressure. Vacuum measurements must, therefore, be less than zero. Negative gauge pressure generally is defined as the difference between a given system vacuum and atmospheric pressure.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/12/PullDontPush_Fig2.JPG" style="width: 595px; height: 688px;" title="2. Absolute pressure gauge measures vacuum as the difference in mercury level in its two legs." /></p> <p><strong>Industrial vacuum systems</strong></p> <p>Vacuums fall into three ranges:</p> <p>&bull; Rough (or coarse), up to 28 in.-Hg<br /> &bull; Middle (or fine), up to one micron<br /> &bull; High, greater than one micron</p> <p>Almost all industrial vacuum systems are rough. In fact, most lifting and work-holding applications operate at vacuum levels of only 12 to 18 in.-Hg. That&rsquo;s because, typically, it&rsquo;s more economical to increase the lifting or holding force by increasing the contact area between the work piece and vacuum cup than it is to pull a higher vacuum and use the same contact area.</p> <p>Middle vacuum handles process applications, such as molecular distillation, freeze drying, degassing, and coating operations. High vacuums are used in laboratory instruments, such as electron microscopes, mass spectrometers, and particle accelerators.</p> <p>A typical vacuum system consists of a vacuum source (mechanical pump or vacuum generator), delivery lines, fittings, and various control valves, switches, filters, and protective devices. Leakage prevention is especially important with vacuum systems, because even the tiniest of leaks can greatly diminish performance and efficiency. It&rsquo;s important to only use tubing designed for vacuum service. Otherwise, the walls of the tubing could collapse under a vacuum and block flow. Also, vacuum lines should be as short and narrow as is practical to limit the volume of air that must be evacuated.</p> <p>Work-holding applications should only use the vacuum pump to reach the required vacuum level. Once the work piece comes in contact with the vacuum cup and achieves the required vacuum, de-energizing a normally closed valve will hold the vacuum indefinitely&mdash;provided there are no leaks. Holding a vacuum in this manner consumes no energy and avoids having to operate the vacuum pump continuously.</p> <p>Companies also offer proprietary devices, such as vacuum cups with integral valves and valves that terminate flow from a cup that exhibits excessive leakage. This valve is designed to avoid false-alarm shutoff when holding porous work pieces (such as cardboard), yet prevent a leak at one vacuum cup from reducing vacuum at an adjacent cup.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/12/PullDontPush_Fig3.JPG" style="width: 595px; height: 337px;" title="3. U-tube manometer, filled with mercury, measures vacuum as a difference between vacuum source and atmospheric pressure." /></p> <p><strong>Vacuum sources</strong></p> <p>A <strong>mechanical vacuum pump</strong> may be thought of as a compressor that operates with its intake below atmospheric pressure and the discharge at atmospheric pressure. Compressors and vacuum pumps have identical pumping mechanisms. The vacuum pump, however, is simply piped to withdraw air from a closed container and exhaust to atmosphere, while the compressor does the opposite.</p> <p>Although compressors and vacuum pumps share many similarities, two significant differences between them must be considered in system design. The maximum change in pressure produced by a vacuum pump is limited; it can never be higher than atmospheric pressure. Plus, increasing vacuum causes a continuous drop in the volume of air passing through the pump. Therefore, the pump itself must absorb virtually all generated heat. A rising vacuum level means less air is present to carry away the generated heat, so the pump must absorb more of that heat.</p> <p>Many machines that require vacuum also use compressed air. In addition, if vacuum is required only intermittently, the already-available compressed air can be used to generate vacuum through a <strong>vacuum generator</strong>, also known as a vacuum ejector.</p> <p>Vacuum generators operate on the <em>venturi</em> principle. Filtered, non-lubricated compressed air enters through inlet <em>A</em>. A diffuser orifice (nozzle), <em>B</em>, causes the air stream to increase in velocity, thereby lowering its pressure and subsequently creating a vacuum in channel <em>C</em>. The air stream exhausts to atmosphere through muffler <em>D</em>.</p> <p>Due to the compact and lightweight nature of vacuum generators, they often can be mounted at or near the point of use. They&rsquo;re inexpensive, and because they have no moving parts, maintenance pales in comparison with mechanical vacuum pumps. They don&rsquo;t need a prime mover because they generate vacuum by tapping into an existing compressed air system. However, retrofitting the generator into a machine may require increasing the capacity of the existing pneumatic system. Heat generation, often a limiting factor with mechanical vacuum pumps, is of little concern with vacuum generators.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/12/PullDontPush_Fig4.JPG" style="width: 595px; height: 251px;" title="4. A Venturi-type vacuum generator produces vacuum from stream of compressed air. Most recent designs pull vacuum to 27 in.-Hg from a source of compressed air of less than 50 psig." /></p> <p><strong>Vacuum source selection</strong></p> <p>To calculate a system&#39;s vacuum needs, consider all work devices to be driven. The devices&rsquo; working vacuum can be determined by calculations based on handbook formulas, theoretical data, catalog information, performance curves, or tests made with prototype systems. After determining the vacuum requirement, the search can begin for pumps that accommodate application needs.</p> <p>The maximum vacuum rating for a pump, which is commonly expressed for either continuous or intermittent duty cycles, can be obtained from manufacturers. Because the maximum theoretical vacuum at sea level is 29.92 in.-Hg, capabilities are based on, and compared to, this theoretical value.</p> <p><strong>How long to reach maximum vacuum?</strong></p> <p>In general, a small capacity source and a large capacity source with equal maximum vacuum capabilities will both produce the same vacuum. It just takes longer with the smaller pump. How much longer depends on the capacity of the source and the size of the system. Simply dividing system volume by open capacity won&#39;t produce the proper answer, though.</p> <p>The higher the vacuum, the fewer air molecules remain in the closed volume. Therefore, fewer molecules can be removed per unit of time. As a result, there&rsquo;s a logarithmic relationship when approaching a perfect vacuum. The time required to pump a system down to a certain vacuum level can be approximated using the following formula:</p> <p><em>t = Vn</em>/<em>q</em></p> <p>where <em>t</em> is time (minutes); <em>V</em> is system volume (ft<sup>3</sup>); <em>q</em> is flow capacity (cfm); and <em>n</em> is a constant for the application.</p> <p>For exact applications, <em>n</em> can be determined by using a natural logarithm. For most purposes, the following will suffice:</p> <p><em>n</em> = 1 for vacuum to 15 in.-Hg<br /> <em>n</em> = 2 for vacuum &gt;15 but &le; 22.5 in.-Hg.<br /> <em>n</em> = 3 for vacuum &ge; 22.5 and up to 26 in.-Hg</p> <p>One further complication&mdash;capacity in the equation is not the open capacity (capacity at atmospheric pressure) usually cataloged by manufacturers. Instead, it represents the average capacity as system pressure drops to the final vacuum level. This value isn&rsquo;t readily available, but can be approximated from manufacturers&#39; performance curves. These curves plot capacity at various vacuum levels.</p> <p>To mesh these curves with the equation, simply substitute values in the equation using capacity readings from the curve at various vacuum levels at 5-in.-Hg increments, up to the desired level. Then total these times.</p> <p>Finally, note that this pump-down time is based on all system components operating at optimum levels. A 25% additional time allowance is recommended to compensate for system inefficiencies and leakage.</p> <table border="0" cellpadding="0" cellspacing="0" width="570"> <tbody> <tr> <td width="41"> <img src="http://insidepenton.com/electronic_design/adobe-pdf-logo-tiny.png" /></td> <td style="padding-left: 0px;" width="459"> <a href="/datasheet/compressed-air-guide-pull-don-t-push-pdf-download">Download this article in .PDF format</a><br /> This file type includes high resolution graphics and schematics when applicable.</td> </tr> </tbody> </table> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/air-compressors/compressed-air-guide-pull-don-t-push#comments Air Compressors Fri, 19 Dec 2014 16:03:00 +0000 30021 at http://hydraulicspneumatics.com Troubleshooting Challenge: Speed Control Causing Unwanted Jolt and Pressure Spike http://hydraulicspneumatics.com/cylinders-actuators/troubleshooting-challenge-speed-control-causing-unwanted-jolt-and-pressure-spike <div class="node-body article-body"><p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/12/201412-Toubleshooting.gif" style="width: 300px; height: 350px; float: right;" />A casting plant used a simple two-speed circuit to extend a hydraulic cylinder at high speed, then shift to a slower speed for forming. The maintenance supervisor used the accompanying schematic to plumb the circuit.</p> <p>A problem occurred when the cylinder shifted to low speed&mdash;the nesting of the steel stamping bounced out of alignment with a hole bored in the fixture. Shifting the two-position directional valve, <em>B</em>, to slow pressing speed produced a jolt and a pressure spike, which caused unwanted movement of the stamping.</p> <p>Maintenance personnel purchased and installed a soft-shift directional valve with a 500-ms shifting speed, but it made the problem worse.&nbsp; They re-installed the original directional valve, <em>A</em>, and installed a pressure gauge in the piping between the cylinder&rsquo;s rod end and the two-position valve. The cylinder had a 5-in. bore and a 3&frac12;-in. rod diameter. They were surprised that the pressures jumped from 350 psi during fast advance to 4,000 psi when the slow-speed meter-out flow control was selected. The pump compensator was set at 2,000 psi.</p> <p>Any idea what caused the problem?</p> <div class="related-content"> <div class="related-label"> Related</div> <p><a href="/hydraulic-pumps-motors/troubleshooting-challenge-unexpected-pressure-loss-while-testing-new-hydrauli">Troubleshooting Challenge: Unexpected pressure loss while testing a new hydraulic power unit</a></p> <p><a href="/cylinders-actuators/troubleshooting-challenge-hydraulic-system-causes-structural-failure">Troubleshooting Challenge: Hydraulic system causes structural failure</a></p> <p><a href="/other-industries/troubleshooting-challenge-eroded-construction-plug-causes-manifold-leak">Troubleshooting Challenge: Eroded Construction Plug Causes Manifold Leak</a></p> </div> <p><strong>Last month&rsquo;s problem:&nbsp;</strong><a href="/hydraulic-pumps-motors/troubleshooting-challenge-unexpected-pressure-loss-while-testing-new-hydrauli"><strong>Unexpected pressure loss while testing a new hydraulic power unit</strong></a></p> <p>When I was manager of a large hydraulic-power-unit (HPU) fabrication shop, we had a strange problem while testing a large HPU. It consisted of a large vane pump, a pilot-operated relief, and a 5-bank D08 manifold with 3-position blocked center directional valves with pressure reducing modules. All of the <em>A</em> and <em>B</em> ports contained pressure gauges. The HPU had a separate off-line filtration and cooling circuit, which we commonly refer to as a kidney loop. The pump was driven by a 100-hp, 1800-rpm electric motor &mdash; a large HPU, but a fairly simple system.</p> <p>The system pressure was set to 2250 psig with an output flow of 75 gpm. The pump would run for 30 to 60 seconds at a time under pressure, but then all pressure would quickly drop to near 0 psig for two to three seconds. Pressure would then quickly jump back up to 2250 psig. This happened 15 to 20 times before the test mechanic called me for help.</p> <p>The unit piping had about &frac12;-in. NPT and &frac12;-in. O-ring connections. No Teflon tape was used, just white, paste-type pipe dope for sealing the NPT connections. We felt the only valve that could cause the malfunction was the pilot-operated relief, so we dis-assembled and inspected it. We did this at least four or five times and could not see any contamination or sticking problem.</p> <p>We were pressed to move onto other units on the test stand, so we drained the oil from the reservoir and removed its access panels, with the eventual plan of retesting it later. However, we noticed that the reservoir bottom was covered with typical construction debris and a rather large amount of small beads of excess pipe dope. <em>Any idea what was causing the problem?</em></p> <p><strong>Solution:</strong></p> <p>Many people do not allow the use of PTFE (Teflon) tape for sealing NPT fittings. However, excessive pipe dope during construction can lead to failure of pilot-operated relief valves when the pipe dope oozes through the control orifice. This causes the valve to open until the pipe dope exits, then the valve resets itself.</p> <p>The unit was dis-assembled, cleaned of all excess pipe dope, re-assembled, tested with good results, and shipped to the customer.</p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/cylinders-actuators/troubleshooting-challenge-speed-control-causing-unwanted-jolt-and-pressure-spike#comments Cylinders & Actuators Fri, 19 Dec 2014 15:42:00 +0000 30011 at http://hydraulicspneumatics.com Hydraulic-Electric Analogies: Capacitors and Accumulators, Part 2 http://hydraulicspneumatics.com/accumulators/hydraulic-electric-analogies-capacitors-and-accumulators-part-2 <div class="field-deck"> Developing an understanding of hydraulic capacitance helps eliminate pesky parasitic capacitances, and facilitates the overall application of circuit theorems in hydraulic design. </div> <div class="node-body article-body"><p><em>This article is the latest in Jack Johnson&#39;s series on Hydaulic-Electric Analogies. See the &quot;Related&quot; articles list below for previous articles in the series.</em></p> <p>Let&rsquo;s examine what happens in an accumulator as the pressure changes, which is almost always the case in hydraulic circuits. The accumulator handles molecules of fluid much like the way a capacitor handles positive electrical charges. Since the hydraulic pressure in this assessment always exceeds the gas pre-charge pressure, the accumulator operates in its active region. As the pressure increases&mdash;say just as it reaches and starts to exceed the pre-charge pressure&mdash;some volume of hydraulic fluid is pushed into the accumulator.</p> <p>If we&rsquo;re considering a piston-type accumulator, the piston moves an amount commensurate with the incoming volume of liquid, further compressing the gas. Increasing the pressure will force even more fluid into the accumulator. Therefore, the pressure rises with each new volume of hydraulic fluid, or conversely, a new volume of fluid enters the accumulator with each new pressure increase.</p> <div class="related-content"> <div class="related-label"> Related</div> <p><a href="/accumulators/hydraulic-electric-analogies-capacitors-and-accumulators-part-1">Hydraulic-Electric Analogies: Capacitors and Accumulators, Part 1</a></p> <p><a href="http://hydraulicspneumatics.com/other-technologies/hydraulic-electric-analogies-part-7-variable-electrical-transformers">Hydraulic-Electric Analogies, Part 7: Variable Electrical Transformers</a></p> <p><a href="http://hydraulicspneumatics.com/other-components/hydraulic-electric-analogies-part-6-coils-cores-and-transformers">Hydraulic-Electric Analogies, Part 6: Coils, Cores, and Transformers</a></p> <p><a href="http://hydraulicspneumatics.com/other-technologies/hydraulic-electric-analogies-part-5-current-and-electrical-fields">Hydraulic-Electric Analogies, Part 5: Current and Electrical Fields</a></p> <p><a href="http://hydraulicspneumatics.com/other-technologies/hydraulic-electric-analogies-part-4-comparing-power-sources">Hydraulic-Electric Analogies, Part 4: Comparing Power Sources</a></p> <p><a href="http://hydraulicspneumatics.com/controls-instrumentation/hydraulic-electric-analogies-part-3-open-and-closed-contradiction">Hydraulic-Electric Analogies, Part 3: The Open and Closed Contradiction</a></p> <p><a href="http://hydraulicspneumatics.com/other-technologies/hydraulic-electric-analogies-part-2-voltage-and-pressure">Hydraulic-Electric Analogies, Part 2: Voltage and Pressure</a></p> <p><a href="http://hydraulicspneumatics.com/technologies/hydraulic-electric-analogies-part-1">Hydraulic-Electric Analogies, Part 1</a></p> </div> <p>Furthermore, each new pressure increase requires a smaller volume of fluid. The ultimate limit is reached when the volume of hydraulic fluid entering the accumulator equals the original volume. To reach this limit, the gas side would be compressed to the point of occupying zero volume; however, this would require an infinite amount of pressure&mdash;an unrealistic level.</p> <p>A practical limit, on the other hand, is based on the pressure rating of the accumulator and/or the pressure ratings of other circuit components. The net effect is that an increasing pressure results in a volume of fluid entering the accumulator and in turn reducing the volume occupied by the compressible gas. When the pressure is reduced, hydraulic volume leaves the accumulator. Thus, flow and pressure are related to the rate at which the pressure changes. When the pressure is constant, no hydraulic fluid enters or leaves, so the flow rate is zero.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/12/2014-12-Motion-Fig-21.gif" style="width: 595px; height: 468px;" title="21. Rising pressure causes flow to enter the accumulator; flow leaves when there’s falling pressure. When the pressure is constant, the flow is zero." /></p> <p>Figure 21 illustrates the idea behind this discussion. The wave shapes are approximate, but reasonably close to what one might observe with an oscilloscope and the appropriate sensors.</p> <p>If one views the electrical charged particles in a manner similar to molecules of oil in the accumulator, then the analogies between capacitors and accumulators is quite good (though it requires a bit more imagination). In reality, absolutely nothing can be seen in the charging of the capacitor. In the accumulator, it&rsquo;s not difficult to imagine the piston or accumulator moving as the hydraulic charge rises and falls. Capacitors require more faith.</p> <table border="0" cellpadding="0" cellspacing="0" width="570"> <tbody> <tr> <td width="41"> <img src="http://insidepenton.com/electronic_design/adobe-pdf-logo-tiny.png" /></td> <td style="padding-left: 0px;" width="459"> <a href="/datasheet/hydraulic-electric-analogies-capacitors-and-accumulators-part-2-pdf-download">Download this article in .PDF format</a><br /> This file type includes high resolution graphics and schematics when applicable.</td> </tr> </tbody> </table> <p><strong>Charging capacitors and accumulators</strong></p> <p>When a capacitor is charged, it means that a separation of charges exists on its two respective plates. Some force figuratively speaking, reaches into, say, the upper plate and pulls electrons away from their parent atoms, and then deposits the electrons on the lower plate <em>(Fig. 22)</em>. This leaves the upper plate positively charged because there&rsquo;s a shortage of electrons (the parent atoms), while the lower plate has a negative charge caused by an excess of negative charges. Due to the charge separation, an electrostatic field exists in the space (dielectric material) between the plates.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/12/2014-12-Motion-Fig-22.gif" style="width: 595px; height: 496px;" title="22. The capacitor is charged when electrons are deposited on one plate after being pulled away from their parent atoms on the opposing plate. It results in a voltage difference—and an electrostatic field in the dielectric—between the two plates." /></p> <p>By convention, the electric field, indicated by the arrows, begins on the positive charges and ends on the negative charges. If one were to connect the two leads of a voltmeter to the capacitor&rsquo;s two leads, there would be a potential difference, i.e., a voltage. We have no way of knowing how much voltage, though, without more information. It could be one or two volts, or it could be several thousand. However, it&rsquo;s not important at this point in the discussion.</p> <p>Analogously, if an accumulator was charged up with a hydraulic power supply, a measurable pressure would reside at the inlet/outlet hydraulic port. Indeed, some source of pressure had to be used to build up the gas pre-charge. Then, some hydraulic power source had to generate the pressure that forced all of those hydraulic-fluid molecules into the inlet/outlet port. The hydraulic source that put the hydraulic charge into the accumulator was a pump of some kind. Without allowing any leakage out of the hydraulic port, that pressure will stay locked inside the accumulator due to compression of the gas. The gas serves as a pneumatic spring. The gas has energy stored in it by virtue of its compression.</p> <p>If the hydraulic port suddenly opens, the hydraulic fluid would spurt out, possibly in an explosive manner, spewing hydraulic fluid in whatever direction the throat was pointed. What means was used to provide the hydraulic charge? We cannot reach into the reservoir and cram the fluid molecules into the accumulator in a literal sense. Rather, the hydraulic charge results from connecting it to a hydraulic pump. The pump would have placed the hydraulic charge in the accumulator.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/12/2014-12-Motion-Fig-23_0.gif" style="width: 200px; height: 200px; float: left;" title="23. A battery or other dc voltage source will transfer charges from one plate and deposit them on the other, thus charging the capacitor." />The same scenario holds true with the capacitor. Of course, we can &ldquo;reach into a plate,&rdquo; pull out electrically charged particles, and &ldquo;deposit them on the other plate&rdquo; only in a figurative or metaphoric way. The normal way is to transfer charges from one plate to the other with a battery or other dc power supply <em>(Fig. 23)</em>.</p> <p>The charged capacitor can be removed from the charging circuit and the charge will remain because of the energy stored in the electrostatic field between the plates. In time, the charge will leak off because the dielectric material isn&rsquo;t a prefect insulator. Charge retention time depends on the amount of capacitance and the quality of the insulating properties in the dielectric separator.</p> <p>In the picofarad range, leakage discharge is essentially instantaneous. In the tens or hundreds of microfarads, charge retention may be measured in hours. If the charge voltage is high enough, and if a human being touches both capacitor leads at the same time, an electrical shock can result. Rapid capacitor discharge can be achieved by merely connecting (shorting) the leads together, but the current can be instantaneously extremely high, damaging the capacitor.</p> <p><strong>Charge retention in the accumulator</strong></p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/12/2014-12-Motion-Fig-24.gif" style="width: 300px; height: 450px; float: right;" title="24. A variable pressure supply can be used to hydraulically charge an accumulator. A manual shutoff valve allows the charged accumulator to be removed from the circuit." />Similar charge retention occurs in accumulators. If the accumulator is charged and its hydraulic path blocked <em>(Fig. 24)</em>, it can be removed from its charging circuit. Thus, energy stored in the compressed gas will be retained. That energy can be used elsewhere at some other time.</p> <p>This type of situation occurs in some large engine starting circuits employed in hydraulic motors. The accumulator is charged during normal engine operation and later discharged through the starter motor at engine-start time. If a system has substantial time between their charging and eventual discharge, the pre-charge gas will often have a different temperature for the pre-charge gas. If the discharge temperature is lower than the hydraulic charging pressure at charging time, the discharge pressure will be lower, creating the appearance that the accumulator has leaked. It in fact did not leak, but thermal energy passed through the accumulator housing and reduced the internal energy as a result of apparent leakage.</p> <p>However, accumulators that retain their charge after machine shutdown can be dangerous to maintenance workers. Opening a circuit containing a hydraulically charged accumulator is the same as opening a functioning hydraulic circuit, and could result in serious personal injury or even death. Most circuits with accumulators are required to automatically dump the hydraulic charge when the machine goes into shutdown. The context here is the difference between the gas pre-charge and in-use hydraulic charge. The gas pre-charge need not be released at machine shutdown because the piston or the anti-extrude poppet in bladder types offer personnel protection internal to the accumulator.</p> <p>If the gas-charging valve or hydraulic valve should leak, the accumulator will lose its charge, much like capacitors. An external gas connection on a piston accumulator like that shown in last month&rsquo;s &ldquo;<a href="http://hydraulicspneumatics.com/accumulators/hydraulic-electric-analogies-capacitors-and-accumulators-part-1" target="_blank">Hydraulic-Electric Analogies: Capacitors and Accumulators, Part 1</a>&rdquo; <em>(Fig. 18 in the article)</em> can be used to increase capacitance. The new capacitance is limited only by the volume of the external gas container. The accumulator&rsquo;s ability to react quickly to sudden demands for hydraulic flow is limited by any restrictions between the external gas container and the accumulator.</p> <p>There&rsquo;s no real analogy to the accumulator&rsquo;s ability to conduct hydraulically whenever the external hydraulic pressure exceeds the gas pre-charge pressure. The phenomenon is more complex than any known, basic electronic gadgets.</p> <table border="0" cellpadding="0" cellspacing="0" width="570"> <tbody> <tr> <td width="41"> <img src="http://insidepenton.com/electronic_design/adobe-pdf-logo-tiny.png" /></td> <td style="padding-left: 0px;" width="459"> <a href="/datasheet/hydraulic-electric-analogies-capacitors-and-accumulators-part-2-pdf-download">Download this article in .PDF format</a><br /> This file type includes high resolution graphics and schematics when applicable.</td> </tr> </tbody> </table> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/accumulators/hydraulic-electric-analogies-capacitors-and-accumulators-part-2#comments Accumulators Other Technologies Other Components Thu, 18 Dec 2014 19:14:00 +0000 29991 at http://hydraulicspneumatics.com Maintain a Fluid Situation http://hydraulicspneumatics.com/hydraulic-fluids/maintain-fluid-situation <div class="field-byline"> Staff </div> <div class="field-deck"> Choosing the right filter for your hydraulic system can neutralize, or substantially mitigate, the potentially devastating effects of contaminant infiltration. </div> <div class="node-body article-body"><p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/12/Filtration-Fig-1.jpg" style="width: 595px; height: 417px;" title="Three-body mechanical interactions can result in interference (a). Two-body wear is a common occurrence in hydraulic components (b). Hard particles can create three-body wear to generate more particles (c). In addition, particle effects can trigger surface wear (d)." /></p> <p>Hydraulic fluids perform four basic functions. Their primary function is to create force and motion as flow converts to pressure near the point of use. Second, by occupying the space between metal surfaces, the fluid forms a seal, which provides a pressure barrier and helps exclude contaminants. A third and often misunderstood function is lubrication of metal surfaces. The fourth and final function is to cool system components.</p> <p>If any one of these functions becomes impaired, the hydraulic system will not perform as designed, and perhaps lead to sudden and catastrophic failure. The resulting downtime can easily cost a large manufacturing plant thousands of dollars an hour. Hydraulic-fluid maintenance, which involves implementation of a continuous program to minimize and remove contaminants, can help prevent or reduce those unplanned downtimes.</p> <p>Aside from human interference, the most common source of system impairment is fluid contamination. Contamination can exist as solid particles, water, air, or reactive chemicals, all of which impair fluid functions in one way or another.</p> <div class="related-content"> <div class="related-label"> Related</div> <p><a href="/hydraulic-fluids/proposed-standard-addresses-bio-friendly-hydraulic-fluids">Proposed Standard Addresses Bio-Friendly Hydraulic Fluids</a></p> <p><a href="/hydraulic-fluids/two-sound-reasons-use-multigrade-hydraulic-fluid">Two Sound Reasons to Use a Multigrade Hydraulic Fluid</a></p> <p><a href="/blog/tried-true-ways-dealing-air-hydraulic-fluid">Tried &amp; True Ways of Dealing with Air in Hydraulic Fluid</a></p> </div> <p><strong>Sources of contaminants</strong></p> <p>Contaminants enter a hydraulic system in various ways, such as:</p> <p>&bull; Built-in during manufacturing and assembly processes<br /> &bull; Internal generation during normal operation<br /> &bull; Ingested from outside the system during normal operation</p> <p>If not properly flushed out, contaminants from manufacturing and assembly will be left in the system. These contaminants include dust, welding slag, rubber particles from hoses and seals, sand from castings, and metal debris from machined components. Also, fluid that&rsquo;s initially added to the system probably comes with a certain amount of contamination, such as various types of dust particles and water.</p> <p>During system operation, dust also enters through breather caps, imperfect seals, and any other openings. Furthermore, system operation generates internal contamination. This occurs as component wear debris and chemical byproducts from fluid and additive breakdown due to heat or chemical reactions. Such materials then react with component surfaces to create even more contaminants.</p> <p><strong>Contaminant interference</strong></p> <p>In broad terms, contaminant interference manifests itself as either mechanical or chemical interaction with components, fluid, or fluid additives. Mechanical interactions range from blockage of passages by hard or soft solid particles, to wear between particles and component surfaces <em>(see the figure)</em>. Chemical reactions include formation of rust or other oxidation, conversion of the fluid into unwanted compounds, depletion of additives (sometimes involving harmful byproducts), and production of biochemicals by microbes in the fluid.</p> <p>Any of these interactions will be harmful. Without preventive measures and fluid conditioning, their negative effects can escalate to the point of component failure. One of the most common failure modes is excessive wear due to loss of lubrication.</p> <table border="0" cellpadding="0" cellspacing="0" width="570"> <tbody> <tr> <td width="41"> <img src="http://insidepenton.com/electronic_design/adobe-pdf-logo-tiny.png" /></td> <td style="padding-left: 0px;" width="459"> <a href="/datasheet/maintain-fluid-situation-pdf-download">Download this article in .PDF format</a><br /> This file type includes high resolution graphics and schematics when applicable.</td> </tr> </tbody> </table> <p><strong>Filter media</strong></p> <p>The filter media is the part of the element that actually contacts a contaminant and captures it for subsequent removal. The nature of the particular filter media and the contaminant-loading process designed into the element explains why some elements last longer in service than others.</p> <p>During manufacture, media usually starts out in sheet form, and then is pleated to expose more surface area to the fluid flow. This reduces pressure differential across the element while increasing dirt-holding capacity. In some designs, the filter media may have multiple layers and mesh backing to achieve certain performance criteria. After being pleated and cut to the proper length, the two ends are fastened together using a special clip, adhesive, or other seaming arrangement to form a cylinder. The most common media include wire mesh, cellulose, and fiberglass composites, or other synthetic materials.</p> <p>Filter media is generally classified as either surface or depth type:</p> <p><strong>Surface media</strong>: For surface-type filter media, the fluid stream flows in a straight path through the element. Dirt is captured on the surface of the element facing the fluid flow. Surface-type elements are generally made from woven-wire cloth. Because the process used to manufacture the wire cloth can be controlled very accurately, and the wire is relatively stiff, surface-type media have a consistent pore size. This consistent pore size is the diameter of the largest hard spherical particle that will pass through the media under specified test conditions. However, during use, the build-up of dirt on the element surface will reduce the pore size and allow the media to capture particles smaller than the original pore-size rating. Conversely, particles (such as fiber strands) that have smaller diameters but greater length than the pore size may pass downstream through surface media.</p> <p><strong>Depth media</strong>: For depth-type filter media, fluid is forced to take convoluted, indirect paths through the element. Because of its construction, depth-type media have many pores of various sizes formed by the media fibers. This maze of multi-sized openings throughout the material traps contaminant particles. Depending on the distribution of pore sizes, the media can have a very high capture rate for very small particle sizes.</p> <p>The two basic media used for depth-type filter elements are cellulose (or paper) and fiberglass. The pores in cellulose media tend to have a broad range of sizes and are very irregular in shape due to the irregular size and shape of the fibers. In contrast, fiberglass media consist of synthetic fibers very uniform in size and shape. These fibers, generally thinner than cellulose fibers, have a consistently circular cross-section. The differences between these typical fibers account for the performance advantage of fiberglass media.</p> <p>Thinner fibers can provide more pores in a given area. Furthermore, thinner fibers can be arranged closer together to produce smaller pores for finer filtration, resulting in improved dirt-holding capacity and filtration efficiency.</p> <p><strong>Filter types and locations</strong></p> <p>The type of filter&mdash;suction, return, pressure, or off-line&mdash;and its physical location in the circuit are almost inseparable by definition.</p> <p><strong>Suction filters</strong> serve to protect the pump from fluid contamination. They are located upstream from the pump&rsquo;s inlet port. Some may be simple inlet strainers, submersed in fluid in the tank. Others may be mounted externally. In either case, suction filters have relatively coarse elements, due to cavitation limitations of pumps. (Some pump manufacturers do not recommend the use of a suction filter; always consult the pump manufacturer for inlet restrictions.) For this reason, suction filters don&rsquo;t serve as a system&rsquo;s primary protection against contamination. In fact, the use of suction strainers and filters has signifcantly decreased in modern hydraulic equipment.</p> <p><strong>Return filters</strong> may be the best choice if the pump is particularly sensitive to contamination. In most systems, the return filter is the last component that fluid passes through before entering the reservoir. Therefore, it captures wear debris from all of the system&rsquo;s working components and any particles that enter through worn cylinder rod seals before such contaminant can enter the reservoir and be pumped back into the system. Because this filter is located immediately upstream from the reservoir, its pressure rating and cost can be relatively low.</p> <p>Note that retracting some cylinders with large diameter rods may result in flow multiplication. This high return-line flow rate may open the filter bypass valve, allowing unfiltered fluid to pass downstream. This probably is an undesirable condition and should be considered when specifying the filter.</p> <p><strong>Pressure filters,</strong> located downstream from the system pump, handle the system pressure. They are sized for the specific flow rate at their location along the pressure line. Pressure filters are especially suited for protecting sensitive components, such as servovalves, directly downstream from the filter. Because pressure filters are located just downstream from the pump, they also help protect the entire system from any pump-generated contamination.</p> <p><strong>Duplex filters</strong>, a common special configuration, may include both pressure and return filters. Duplex filters provide continuous filtration. They have two or more filter chambers with internal passageways and valves to allow for uninterrupted operation. When one filter element needs servicing, the duplex valve is shifted, diverting flow to the opposite filter chamber. Then the dirty element can be changed, while flow continues to pass through the cleaner element. The duplex valve typically is an open crossover type, which prevents any flow blockage.</p> <p><strong>Off-line filtration </strong>operates independent of a machine&rsquo;s main hydraulic system. This increasingly popular filtration arrangement (also referred to as <em>recirculating</em>, <em>kidney loop</em>, or <em>auxiliary filtration</em>) is attractive as a retrofit project for problem systems. An off-line filtration circuit includes its own pump and electric motor, a filter, and the appropriate connecting hardware. These components are installed off-line as a small subsystem separate from the working lines, or they may be included in a fluid-cooling loop. Fluid is pumped continuously out of the reservoir, through the off-line filter, and back to the reservoir. A rule of thumb: The off-line pump should be sized to flow a minimum of 10% of the main reservoir volume.</p> <p>With its <em>polishing</em> effect, off-line filtration is able to maintain the system&rsquo;s fluid at a constant contamination level. As with a return line filter, the off-line loop is best suited to maintain overall system cleanliness; it doesn&rsquo;t provide protection for specific components. An added advantage of an off-line filtration loop is that it&rsquo;s relatively easy to retrofit on an existing system with inadequate filtration. Also, the off-line filter can be serviced without shutting down the main system.</p> <table border="0" cellpadding="0" cellspacing="0" width="570"> <tbody> <tr> <td width="41"> <img src="http://insidepenton.com/electronic_design/adobe-pdf-logo-tiny.png" /></td> <td style="padding-left: 0px;" width="459"> <a href="/datasheet/maintain-fluid-situation-pdf-download">Download this article in .PDF format</a><br /> This file type includes high resolution graphics and schematics when applicable.</td> </tr> </tbody> </table> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/hydraulic-fluids/maintain-fluid-situation#comments Hydraulic Filters Hydraulic Fluids Thu, 18 Dec 2014 18:30:00 +0000 29971 at http://hydraulicspneumatics.com A Noteworthy Keynote at the International WorkBoat Show http://hydraulicspneumatics.com/marine-offshore/noteworthy-keynote-international-workboat-show <div class="node-body article-body"><p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/12/CaptainP.jpg" style="width: 300px; height: 444px; float: left;" title="Captain Phillips, starring Tom Hanks, was released in 2014. (Image courtesy of IMDb)" />One of the keynote speakers at the <a href="http://www.workboatshow.com" target="_blank">International WorkBoat Show</a> &mdash; held December 3 to 5 in New Orleans &mdash; was Richard Phillips, the former captain of the MV Maersk Alabama, a container ship that was hijacked by pirates April 8, 2009 off the coast of Somalia. Phillips was taken hostage and rescued by the U.S. Navy on April 12. His presentation described events before, during, and after the hijacking, and he provided several interesting details in a Q&amp;A session following his prepared speech.</p> <p>The story of the incident is described in a 2010 book, <em>A Captain&rsquo;s Duty: Somali Pirates, Navy SEALs, and Dangerous Days at Sea</em>, by Stephan Talty and Phillips. It is also covered in a movie released last year, <em>Captain Phillips</em>, starring Tom Hanks. I saw the movie a few days before leaving for New Orleans, so it was still fresh in my mind. And I won&rsquo;t spoil the plot of book or movie by revealing any details here.</p> <div class="related-content"> <div class="related-label"> Related</div> <p><a href="/marine-offshore/workboat-show-chugs-nola">WorkBoat Show Chugs into NOLA</a></p> <p><a href="/marine-offshore/deep-seas-push-hydraulic-system-boundaries">Deep Seas Push Hydraulic-System Boundaries</a></p> <p><a href="/blog/hydraulics-aftermath-pearl-harbor">Hydraulics in the Aftermath of Pearl Harbor</a></p> </div> <p>In addition to his experiences, the keynote also described some of the emotions Phillips went through. He said it was essential that he had adopted a never-give-up attitude to get him through his ordeal. I remember several times in the movie where I probably would not have had the strength to carry on the way Phillips did. But he said he didn&rsquo;t think he had more strength or courage than any of us in the audience would&rsquo;ve had under the same circumstances. He said that if any of us had encountered the same life-or-death situations, we probably would&rsquo;ve been able to find the same inner strength to survive.</p> <p>Phillips described a personal revelation that gave him the inspiration to never give up no matter what the challenge. He said his wife normally spent time with him at the airport whenever he left on one of his excursions. But at the beginning of this particular trip, they were running late, so she just dropped him off at the airport. He said that if anything happened to him, he knew his wife would never forgive herself for not spending time with him at the beginning of this trip. He said that thought inspired him to keep persevering and made him realize that once you give up it&rsquo;s all over.</p> <p>But attending a show is not a life-or-death situation, so I figured it would be okay for me to call it quits after a long day and head back to my hotel room a half hour before the show closed to rest my weary feet.&nbsp;</p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/marine-offshore/noteworthy-keynote-international-workboat-show#comments Marine & Offshore Hydraulic Fluids Thu, 18 Dec 2014 18:16:00 +0000 29961 at http://hydraulicspneumatics.com The Importance of Making A List... And Checking It Twice http://hydraulicspneumatics.com/blog/importance-making-list-and-checking-it-twice <div class="node-body blog-body"><p>In a recent accident investigation I was involved in, a man was riding unrestrained on the forks of a forklift. While at height, the forks dropped several inches without warning, causing the man standing on the forks to lose his footing and fall to floor. He was seriously injured. The operator was not operating any controls when the forks lost height.<br /> <br /> Despite the contributory negligence of the injured party - he was aware that riding on the forks of a forklift without a man cage is not a safe or acceptable practice - a case was brought against a contractor who had performed maintenance work on the forklift prior to the incident.<br /> <br /> According to witness reports, the contractor&#39;s service technician had been called in to replace a burst hydraulic hose. As a consequence, the presence of air in the hydraulic system - allegedly the result of the service technician&#39;s failure to properly bleed the system after replacing the hose - was advanced as the cause of the sudden dropping of the forks by the expert witness for the injured party.<br /> <br /> Was air in the hydraulic system the cause of this accident? Well as they often are, the technical arguments surrounding this question were complex. Beyond the physics involved, the complexity of the issue is compounded by the fact that the mechanism for elevating the forks on a forklift typically uses a single-acting, telescopic cylinder with a chain and pulley arrangement. Amongst other things, this results in relative fork movement double that of cylinder movement.<br /> <br /> But the more revealing question and moral to this story is: how could this lawsuit (if not the incident) have been avoided in the first place?<br /> <br /> What struck me as I reviewed the facts of this case, was the technician who repaired the forklift prior to the incident left the door open to litigation by his failure to do one simple thing. Had he taken the 10-minutes necessary to do it, the lawsuit would never have got off the ground. It was even spelt out for him, if only he&#39;d looked - or been trained to do so.<br /> <br /> I&#39;m talking about following proper procedure, and checking it off.<br /> <br /> The aviation and aerial access industries have something significant in common. And that is, if you use a mechanical device to defy gravity, you should leave as little to chance as possible. If a jetliner or aerial work platform comes down in an uncontrolled fashion, people get killed or injured.<br /> <br /> In the aviation industry, nothing happens by way of aircraft operation or maintenance without a procedure and a corresponding checklist. This is the foundation of the industries&#39; excellent safety record -- which is the premise on which the public&#39;s confidence in air travel is based.<br /> <br /> The same can&#39;t always be said about the aerial access industry specifically - and the hydraulics industry generally. In fact, the use of procedures and checklists is such a valuable and yet much overlooked aspect of hydraulic equipment maintenance, that I spend a whole chapter outlining its many benefits in <a href="http://www.hydraulicsupermarket.com/track?p=handp&amp;w=isthsp"><strong>Insider Secrets to Hydraulics</strong></a>.<br /> <br /> In the situation above, had the technician looked in the forklift&#39;s operating manual, he would have found a procedure to be followed before the machine was returned to service - after repairs had been carried out on the hydraulic system.<br /> <br /> Among other things, this procedure involved carrying out a functional load test. Had the technician followed this procedure and documented it properly, it would have eliminated the possibility of litigation arising from deficient maintenance practices.<br /> <br /> Bottom line: not following documented procedure before returning a hydraulic machine to service after maintenance work has been carried out can be a costly mistake. To discover six other costly mistakes you want to be sure to avoid with your hydraulic equipment, <a href="http://www.hydraulicsupermarket.com/track?p=handp&amp;w=smr"><strong>get &quot;Six Costly Mistakes Most Hydraulics Users Make... And How You Can Avoid Them!&quot; available for FREE download here</strong></a>.</p> </div> <div class="og_rss_groups"><ul class="links"><li class="og_links first last"><a href="/blog/hydraulics-work">Hydraulics At Work</a></li> </ul></div> http://hydraulicspneumatics.com/blog/importance-making-list-and-checking-it-twice#comments Hydraulics At Work Mon, 15 Dec 2014 21:36:00 +0000 29931 at http://hydraulicspneumatics.com Ohio Town Welcomes First Hydraulic Hybrid Garbage Trucks http://hydraulicspneumatics.com/news/ohio-town-welcomes-first-hydraulic-hybrid-garbage-trucks <div class="field-deck"> Ohio town seizes opportunity from disaster </div> <div class="node-body article-body"><p>Shortly after midnight on February 15, 2014, firefighters in Oberlin, Ohio responded to a fire at the city&rsquo;s refuse vehicle garage. The building housed the city&rsquo;s fleet of six garbage and recycling trucks. All of them were destroyed. Scott Broadwell, President of Oberlin&rsquo;s City Council, said it was fortunate that no one was injured in the incident, and leadership for the city of Oberlin acted quickly by renting two trucks to begin waste collection the following Tuesday. Jeff Baumann, Publics Works Director for the city, explained, &ldquo;We normally don&rsquo;t collect residential waste on Mondays, but because we were able to have trucks on the streets by Tuesday, residents saw no interruption in service.&rdquo; Both agreed that the fire breaking out in the middle of the night helped prevent injuries because people were not in the service garage at the time.</p> <p><a href="/site-files/hydraulicspneumatics.com/files/uploads/2014/12/ Alan2.JPG" target="_blank"><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/12/%20Alan2.JPG" style="width: 399px; height: 275px; float: right; margin-left: 4px; margin-right: 4px;" title="The author is shown with one of three hydraulic hybrid refuse trucks at the city of Oberlin, Ohio. Click on image for larger view." /></a>But renting trucks was a temporary solution, so when officials met to devise a permanent solution, leadership recommitted to its zero-waste policy. As a result, they decided to replace the fleet with hydraulic hybrid trucks. The action came from joint efforts between the city of Oberlin, Oberlin College, and the Ohio Environmental Protection agency to obtain three new collection trucks using the RunWise hydraulic hybrid drive system from Parker Hannifin Corp. As part of this commitment, Oberlin received a grant of $200,000 from the Ohio Environmental Protection Agency to replace the fleet with the hydraulic hybrid trucks. Funds were also proved by the Green Edge Fund at Oberlin College.</p> <h3> Hydraulic hybrid operation</h3> <p>The RunWise system in the Oberlin trucks uses three Parker C24 pump/motors. The C24 is a bent-axis piston pump/motor featuring several proprietary design and construction characteristics for this application. One pump is driven by the truck&rsquo;s engine for pressurizing the system. Each of the other two is connected to a rear wheel drive to capture braking energy to decelerate the truck and to accelerate the vehicle using the stored energy. Other key components of the system are accumulators that capture and release braking energy.</p> <p><a href="/site-files/hydraulicspneumatics.com/files/uploads/2014/12/ HydraulicsLR.jpg" target="_blank"><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/12/%20HydraulicsLR.jpg" style="width: 300px; height: 196px; margin-left: 4px; margin-right: 4px; float: left;" title="Open access panel reveals hydraulic components. White cylinder at extreme left is aerator. The tow black cylinders to its right are hydraulic filters, and the two large horizontal cylinders at far right are low-pressure accumulators., Click on image for larger view." /></a>In essence, when the driver depresses the brake pedal, the two rear pump/motors act as pumps by transmitting the kinetic energy of the moving truck into hydraulic power. This energy conversion decelerates the truck, and the hydraulic energy is stored in the accumulators. When the driver then depresses the accelerator pedal, the hydraulic energy is released from the accumulators to drive the pump/motors, accelerating the truck.</p> <h3> Multiple modes of savings</h3> <p>Ben Mather, VP of Operations for Parker&rsquo;s Hydraulics Group, said that without the RunWise System, each of Oberlin&rsquo;s trucks would consume about 8,600 gal of fuel per year. The RunWise system is expected to cut fuel consumption roughly in half, saving Oberin more than 4,000 gal of fuel per year for each truck. Tom DeCoster, Business Development Manager for Parker&rsquo;s Hydbrid Drive Div., added, &ldquo;The RunWise system regenerates more than 70% of braking energy, so brakes last about eight times longer with RunWise. The downtime and cost of labor and parts for these trucks are substantial. A conventional refuse truck might need to have its brakes serviced two or three times a year, but, potentially, the brakes in these trucks could last the life of the vehicle.&rdquo;</p> <p>Another benefit of the RunWise system is lower emissions. Mather continued, &ldquo;By using hydraulics to regenerate braking energy into vehicle acceleration, we reduce CO<sub>2</sub> emissions from each truck that&rsquo;s equal to taking nearly seven cars off the road. Furthermore, the vehicles run quieter. You won&rsquo;t hear brakes squealing as these trucks make frequent stops, and you won&rsquo;t hear the engines race to accelerate the vehicle to the next stop.&rdquo;</p> <h3> What it&rsquo;s made of</h3> <p>Again, the RunWise system consists of three Parker C24 bent-axis pump motors. The hydraulic system itself has low- and high-pressure circuits. The engine-driven pump keeps the low-pressure circuit charged to 65 to 70 psi for maintaining positive inlet pressure to the two rear pump-motors driving the wheels.<strong> </strong>However, hydraulic fluid in sealed, pressurized systems tends to retain air. To circumvent this potential problem, the system has a de-aeration tank that allows air to disperse from the hydraulic fluid.</p> <p>Refuse trucks are heavy, but even in these heavy-duty vehicles, more weight means higher fuel consumption. Therefore, the RunWise system is also designed to conserve weight. This is done, in part, by using accumulators with a high-strength, lightweight composite shell. Conventional steel accumulators of this size weigh hundreds of pounds. The composite accumulators weigh</p> <p>less than their steel counterparts in this application. The result is a system that weighs less than if it used steel accumulators.</p> <p>The vehicle drive consists of a transmission coupled to the engine. The transmission either provides power to the hydraulic pump or to a mechanical drive shaft connected to the rear wheels. An electronic drive control not only controls pressure and flow of the hybrid hydraulic system, but also selects the drive mode. When the truck is collecting waste, it travels from one property to another, then stops. This provides the maximum opportunity to regenerate braking energy, and the drive control operates the hydraulic system in its low-speed mode &mdash; for speeds up to about 25 mph.</p> <p>When the vehicle will travel a short distance, say to another street or nearby neighborhood, the control shifts the hydraulic system into its high-speed mode &mdash;between about 25 and 45 mph. The transition is accomplished automatically and with no intervention from the driver. When the vehicle is done with a route and heads for the highway, the drive control automatically switches to direct-drive mode. This occurs when speed exceeds about 45 mph, and, again, with no driver intervention. So whether the vehicle is collecting waste with frequent stops from one home to another, travelling from one neighborhood to another, or heading for a landfill or recycling facility, the control always puts the drive in the most economical mode.</p> <h3> <strong>A bright future</strong></h3> <p>DeCoster said the potential growth for hybrid drives led Parker to form its Hybrid Drive System Div., located in Columbus, Ohio, in 2011. He offered, &ldquo;We now have 160 refuse trucks using our RunWise system in North America alone, plus another 48 that are used in delivery trucks.&rdquo; And as with any new technology, its capabilities are expected to improve as more systems come into use.</p> <p><em>For more information, contact Parker&rsquo;s Hybrid Drive Systems Div. at (866) 858-5600, or visit <a href="http://www.parker.com/hybrid">www.parker.com/hybrid</a>.</em></p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/news/ohio-town-welcomes-first-hydraulic-hybrid-garbage-trucks#comments Hydraulic Pumps & Motors News Mon, 15 Dec 2014 20:02:00 +0000 29951 at http://hydraulicspneumatics.com Proposed Standard Addresses Bio-Friendly Hydraulic Fluids http://hydraulicspneumatics.com/hydraulic-fluids/proposed-standard-addresses-bio-friendly-hydraulic-fluids <div class="node-body article-body"><p>Biodegradable hydraulic fluids are being specified with increasing frequency by governmental and industrial entities. A proposed new ASTM International standard, WK31234, <em>Specification for Biodegradable, Low Aquatic Toxicity Hydraulic Fluids</em>, intends to make it easier to ensure that proper hydraulic fluids are being used at environmentally sensitive job sites.

&ldquo;By explicitly demanding conformity to this specification, the responsibility for environmental compatibility is with the lubricant supplier who cites this specification on his technical data sheet,&rdquo; explained ASTM member Patrick Laemmle, CEO, Panolin International Inc.&nbsp; 

</p> <p>The fluids to be covered by ASTM WK31234 are used in industrial and mobile hydraulic equipment. Biodegradable fluids have been found to perform different from traditional mineral oils, creating a need for separate performance classifications.

Laemmle said that manufacturers of pumps, valves, cylinders, hoses and seals could all make use of ASTM WK31234. In addition, Laemmle noted that it should be useful to operators and end users of both stationary and mobile hydraulic equipment. The proposed standard could also be used for government purposes. 
</p> <p>ASTM WK31234 is being developed by Subcommittee D02.N0.03 on ECO-Evaluated Fluids, part of <strong><a href="http://www.astm.org/COMMITTEE/D02.htm" target="_blank">ASTM Committee D02</a></strong> on Petroleum Products, Liquid Fuels and Lubricants. Laemmle said that all interested parties, particularly original equipment manufacturers, are welcome to participate in the ongoing standards development activities of D02.N0.03.
&nbsp;
ASTM welcomes participation in the development of its standards. Become a member at <strong><a href="http://www.astm.org/JOIN" target="_blank">www.astm.org/JOIN</a></strong>.
&nbsp;</p> <p>The next ASTM Committee D02 meeting will be held <strong>June 21-25, 2015</strong>, in Ft. Lauderdale, Fla.
 The contact for technical inquiries to the subcommittee is Patrick Laemmle, Panolin America Inc., Ventura, Calif. Call him at (805) 676-1193 or email <a href="mailto:patrick.laemmle@panolin.com?subject=Inquiry%20about%20ASTM%20subcommittee%20D02">patrick.laemmle@panolin.com</a>.
</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/12/ASTM%20logo.jpg" style="width: 250px; float: right; margin-left: 4px; margin-right: 4px; height: 50px;" />More than 12,000 ASTM standards operate globally. 
Working across borders, disciplines, and industries ASTM harnesses the expertise of more than 30,000 members to create consensus and improve performance in manufacturing and materials, products and processes, systems and services. 
For more news in this sector, visit <strong><a href="http://www.astm.org/sn-energy" target="_blank">www.astm.org/sn-energy</a></strong>.</p> <p>&nbsp;</p> <p>&nbsp;</p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/hydraulic-fluids/proposed-standard-addresses-bio-friendly-hydraulic-fluids#comments Hydraulic Fluids Thu, 11 Dec 2014 17:53:00 +0000 29921 at http://hydraulicspneumatics.com Two Sound Reasons to Use a Multigrade Hydraulic Fluid (.PDF Download) http://hydraulicspneumatics.com/datasheet/two-sound-reasons-use-multigrade-hydraulic-fluid-pdf-download <div class="node-body datasheet-body"><p>The most common reason for using a multigrade hydraulic oil is to maintain viscosity within acceptable limits across a wide range of temperatures between winter and summer, thereby eliminating the need for seasonal oil changes. However, there is another case for considering the use of...</p> <p><strong>Register or sign in below to download the full article in .PDF format, including high resolution graphics and schematics when applicable.</strong></p> <div class="gatedLogin well"> <div class="contentPadding clearfix"> <h2>Register for Complete Access (Valid Email Required)</h2> <p><p> <img alt="hp top essentials" src="/site-files/hydraulicspneumatics.com/files/uploads/2013/06/hp_topessentials.jpg" style="width: 114px; height: 125px; border-width: 0px; border-style: solid; margin: 5px; float: right;" />By registering on Hydraulics &amp; Pneumatics now, you&#39;ll not only gain access to , you&#39;ll also receive a complimentary copy of <em>Hydraulics &amp; Pneumatics&#39; Top Essentials</em>.</p> </p> <div class="gatedLoginButtons gated-register-button"> <div class="button-region"> <a href="/penton_ur/nojs/user/register/%25step" class="ctools-use-modal btn btn-branded btn-wide ctools-modal-register" title="Register at this site.">Register</a> </div> <div class="loginLinkText"> Already registered? <a href="/penton_ur/nojs/login" class="ctools-use-modal ctools-modal-log_in" title="">Log In</a> here. </div> </div> </div> </div> </div> <div class="og_rss_groups"></div> Gold Tue, 09 Dec 2014 17:20:00 +0000 29901 at http://hydraulicspneumatics.com Two Sound Reasons to Use a Multigrade Hydraulic Fluid http://hydraulicspneumatics.com/hydraulic-fluids/two-sound-reasons-use-multigrade-hydraulic-fluid <div class="field-deck"> Higher system efficiency presents a strong argument for using multigrade hydraulic fluids, but their potential for improved machine productivity can have an even greater impact on your bottom line. </div> <div class="node-body article-body"><table border="0" cellpadding="0" cellspacing="0" width="570"> <tbody> <tr> <td width="41"> <img src="http://insidepenton.com/electronic_design/adobe-pdf-logo-tiny.png" /></td> <td style="padding-left: 0px;" width="459"> <a href="/datasheet/two-sound-reasons-use-multigrade-hydraulic-fluid-pdf-download">Download this article in .PDF format</a><br /> This file type includes high resolution graphics and schematics when applicable.</td> </tr> </tbody> </table> <p>In a case study published in the December 2009 issue of <em>Hydraulics &amp; Pneumatics</em>, a new hydraulic excavator was shipped to site filled with the wrong type of hydraulic oil. The consequence of this mistake was four main pump failures&mdash;at a cost of $20,000 each, three swing motor failures, and two track drive motor failures&mdash;all within the first 27 months of operation. In fact, the total cost of failures, including downtime, amounted to $193,872 over the first two 27 months of this machine&rsquo;s life.</p> <p>Although the hydraulic equipment you&rsquo;re responsible for may not be on the same scale, the principle is the same: If the hydraulic system is not filled with the right type and grade of oil, it won&rsquo;t perform like it should, and it won&rsquo;t last like it should.</p> <h3> Why Hydraulic Fluid is Different from Other Lubricants</h3> <p>Hydraulic fluid is different from other oils. Not only is it a lubricant, it&rsquo;s also the means by which power is transferred throughout the hydraulic system. So it&rsquo;s a lubricant <em>and</em> a power transmission device. This dual role makes it unique.</p> <p><img alt="Fig. 1" height="181" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/12/MRO%20Fig%201.png" style="margin: 5px; float: left;" title="Temperature-viscosity diagram for the &quot;perfect&quot; hydraulic fluid. Note that viscosity flat-lines at 25 centiStokes regardless of temperature." width="294" />To be an effective and reliable lubricant, hydraulic oil must possess properties similar to most other lubes. These include foaming resistance and air release; thermal, oxidative, and hydrolytic stability; anti-wear performance; filterability; demulsibility; rust and corrosion inhibition; and viscosity in respect to its influence on lubricating film thickness&mdash;which is critical for maximum service life of hydraulic components.</p> <p>To be most efficient in its role as a power transmission device, hydraulic oil needs high <em>bulk modulus</em> (high resistance to reduction in volume under pressure) and high viscosity index (low rate of change in viscosity with temperature).</p> <p>As an analogy, consider a V-belt drive. If its tension is out of adjustment, the belt will slip. The result is a higher percentage of input power wasted to heat. This means less power is available at the output to do useful work. In other words, the drive becomes less efficient. A similar situation can occur with hydraulic oil. Change in its bulk modulus or viscosity can affect the efficiency with which power is transmitted in the hydraulic system.</p> <div class="related-content"> <div class="related-label"> Related</div> <p><a href="http://hydraulicspneumatics.com/blog/right-way-do-offline-filtration-hydraulic-systems">The RIGHT Way To Do Offline Filtration On Hydraulic Systems</a></p> <p><a href="http://hydraulicspneumatics.com/blog/how-avoid-hydraulic-accumulator-failure">How to Avoid Hydraulic Accumulator Failure</a></p> <p><a href="http://hydraulicspneumatics.com/rail-truck-bus/ameripride-takes-delivery-first-hydraulic-hybrid-tru">Ameripride Takes Delivery of First Hydraulic Hybrid Truck</a></p> </div> <p>The perfect hydraulic fluid for transmission of power would be infinitely stiff (incompressible) and have a constant viscosity of around 25 cSt, regardless of temperature. Unfortunately, such a fluid does not exist.</p> <h3> The Benefits of Multigrade Fluid</h3> <p>Bulk modulus is an inherent property of the base oil and can&rsquo;t be improved with additives. But viscosity index (VI) can be improved by using high VI base stocks&mdash;such as synthetics&mdash;or by adding polymers called viscosity index improvers to the formulation.</p> <p>Viscosity index improvers were first used to make multigrade engine oils in the 1940s. These days, this common and well-tested technology is used to make high VI (multigrade) oils for other applications, including automatic transmission fluids and manual transmission gear oils. However, the VI improvers used in oils for these applications are not typically shear stable when used in modern hydraulic systems. However recent advances in VI improver technology means that mineral hydraulic oils with a shear stable viscosity index in the 150 to 200 range are now commercially available. (Monograde, mineral hydraulic oils have a typical VI of between 90 and 100.)</p> <p>The most common reason for using a multigrade hydraulic oil is to maintain viscosity within acceptable limits across a wide range of temperatures between winter and summer, thereby eliminating the need for seasonal oil changes. However, there is another case for considering the use of a multigrade hydraulic oil. Within the allowable extremes of viscosity required to maintain adequate film thickness for lubricating hydraulic components, there&rsquo;s a narrower viscosity range where power losses are minimized Therefore, power transfer is maximized. By maintaining the oil&rsquo;s viscosity in this optimum range, machine cycle times are faster (productivity is increased) and power consumption (fuel or electricity) is reduced.</p> <p><img alt="Table" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/12/MRO%20Fig%202%20%28table%29.png" style="width: 595px; height: 396px;" /></p> <p>So using a high VI or multigrade oil means the hydraulic system will remain in its power transmission &ldquo;sweet spot&rdquo; across a wider operating temperature range. You could think of this as similar to installing an automatic-tensioner on the V-belt drive mentioned earlier to maintain optimum power transfer conditions.&nbsp;</p> <p>However, based on simple cost/benefit analysis, if the cost to install the tensioner was $200, this money should not be spent unless we&rsquo;re satisfied this investment can be recovered&mdash;plus an acceptable return&mdash;through savings attributable to more efficient power transmission or reduced maintenance costs.</p> <p>Shear stable, multigrade hydraulic oil is more expensive than monograde, so the same analysis should be applied when evaluating the cost and benefits of using a high VI hydraulic oil. But unlike the relatively simple V-belt drive, savings accruing from increased hydraulic machine performance can be more difficult to quantify.</p> <table border="0" cellpadding="0" cellspacing="0" width="570"> <tbody> <tr> <td width="41"> <img src="http://insidepenton.com/electronic_design/adobe-pdf-logo-tiny.png" /></td> <td style="padding-left: 0px;" width="459"> <a href="/datasheet/two-sound-reasons-use-multigrade-hydraulic-fluid-pdf-download">Download this article in .PDF format</a><br /> This file type includes high resolution graphics and schematics when applicable.</td> </tr> </tbody> </table> <h2> Understanding the Benefits</h2> <table border="0" cellpadding="0" cellspacing="0" width="570"> <tbody> <tr> <td width="41"> <img src="http://insidepenton.com/electronic_design/adobe-pdf-logo-tiny.png" /></td> <td style="padding-left: 0px;" width="459"> <a href="/datasheet/two-sound-reasons-use-multigrade-hydraulic-fluid-pdf-download">Download this article in .PDF format</a><br /> This file type includes high resolution graphics and schematics when applicable.</td> </tr> </tbody> </table> <p>To illustrate the economic benefits possible, consider the following results from a field trial conducted by a manufacturer of shear-stable VI improvers. The performance of a 40-hp compact excavator was evaluated using an all-season, 142 VI multigrade baseline oil and compared to that of the same machine using a 200 VI test oil. The test procedure was as follows:</p> <p>1. Start with 142-VI oil, new air filter, fuel filter.</p> <p>2. Top off fuel to fill neck at start of test.</p> <p>3. Use trenching blade width to normal depth.</p> <p>4. Dig trench for seven hours.</p> <p>5. After seven hours, record fuel to refill.</p> <p>6. Measure trench width, depth, and length.</p> <p>7. Repeat steps 2-6 with second operator.</p> <p>8. After baseline established, change hydraulic oil and filter, run for two hours and repeat oil and filter change with 200 VI oil. (Due to some dilution of the 200 VI oil with the 142 VI baseline oil after changeover, the actual VI of the test oil was less than 200.)</p> <p>9. Repeat steps 2-7.</p> <p>The higher VI test oil demonstrated the following advantages over the baseline oil:</p> <ul> <li> 15.4% improvement in fuel economy&mdash;that is, cubic yards of dirt moved per gallon of fuel consumed.</li> <li> 14.3% improvement in productivity&mdash;that is, cubic yards of dirt moved per hour.</li> </ul> <p>To assign a value to these performance gains, a spreadsheet was developed to calculate an owner&rsquo;s variable costs over the 1000 hour drain interval recommended by the excavator manufacturer. The following assumptions were made:</p> <ul> <li> All seasons baseline oil cost $9/gal and the 200 VI test oil cost $18/gal.</li> <li> Labor and equipment rental cost of $75/hr.</li> <li> Diesel fuel cost of $3.15/gal.</li> </ul> <p>By extrapolating the results of the trial, it was determined that with the baseline oil, the excavator could dig approximately 20,000 yards of trench in 1000 hours. The same size trench could be dug in only 874 hours with the 200 VI test oil. No value was assigned to the additional 126 hr the machine owner could have to used to perform more work with the machine.</p> <p>Based on the field test results and the assumptions stated above, replacing the 142 VI all seasons oil with 200 VI oil would save the machine owner $10,000 every 1000-hr drain interval. And note that while the fuel cost savings are meaningful, the greatest potential benefit from switching to higher VI oil is likely to accrue from machine productivity improvement.</p> <p>As the results of this trial show, the potential economic gain from using a high VI or multigrade oil go beyond the simple elimination of seasonal oil changes to maintain operating viscosity within allowable limits. But the ultimate decision on whether to use a multigrade over a monograde involves weighing cost against benefit, the type of hydraulic machine, its duty cycle, and its temperature operating window.&nbsp;</p> <h3> The Problem with Multigrade Engine Oil</h3> <p>Engine oil <em>can</em> work satisfactorily as a hydraulic fluid. However, if a multigrade engine oil is being used in the hydraulic system specifically for its high viscosity index (VI), then it&rsquo;s not the correct solution. The reason is the additives used to improve viscosity index.</p> <p>Viscosity index improvers are relatively large molecules, which are curled into little balls at low temperatures and don&rsquo;t thicken the oil. At higher temperatures, they uncurl into long chain molecules, which give the oil greater viscosity. The earliest VI improvers used to make multigrade engine oils in the 1940s were basically melted rubber. And this worked well in engine oil.</p> <p>VI improver technology has advanced a lot since then. But even today, because they are long and complex molecules, they are susceptible to &ldquo;shear down&rdquo; as the oil circulates. Hydraulic systems typically produce shearing forces that break the long molecules of these VI improvers, rendering them ineffective at maintaining a stable viscosity at higher temperatures. And in terms of shearing forces, a modern hydraulic system is one of the most challenging there is for VI improvers.</p> <p>Because VI improvers are an expensive additive, oil blenders formulate for the application. So while it would be possible to formulate a multigrade engine oil which would be shear stable when used in a hydraulic system, it would be overkill for the engine application and, therefore, add unnecessary extra cost. As a result, VI improved engine oils, automatic transmission fluids, and manual transmission gear oils typically are not shear stable when used in modern hydraulic systems. This means if they are used as a hydraulic fluid, the VI improvers will shear down over time and lose their ability to provide the necessary viscosity improvement, which defeats the purpose of using them in the first place.</p> <p>So if the temperature operating window of your hydraulic equipment dictates the use of a multigrade oil, or you seek the productivity advantages described here, engine oil is not usually the best choice. A multigrade oil formulated specifically for hydraulic systems should be used instead.</p> <p>Brendan Casey is the founder of <a href="http://HydraulicSupermarket.com" target="_blank">HydraulicSupermarket.com</a> and the author of <em>Insider Secrets to Hydraulics</em>, <em>Preventing Hydraulic Failures</em>, <em>The Hydraulic Troubleshooting Handbook</em>, <em>Hydraulics Made Easy,</em> <em>Advanced Hydraulic Control, </em>and<em> The Definitive Guide to Hydraulic Troubleshooting</em>. A hydraulics specialist with an MBA, he has more than 25 years experience in the design, maintenance, and repair of mobile and industrial hydraulic equipment. For more information, visit his website or <a href="http://hydraulicspneumatics.com/blog/hydraulics-work" target="_blank">read his blog on our website</a>.</p> <table border="0" cellpadding="0" cellspacing="0" width="570"> <tbody> <tr> <td width="41"> <img src="http://insidepenton.com/electronic_design/adobe-pdf-logo-tiny.png" /></td> <td style="padding-left: 0px;" width="459"> <a href="/datasheet/two-sound-reasons-use-multigrade-hydraulic-fluid-pdf-download">Download this article in .PDF format</a><br /> This file type includes high resolution graphics and schematics when applicable.</td> </tr> </tbody> </table> <h2> Learn More about Hydraulics</h2> <p><img alt="Secret to Hydraulics" height="106" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/12/MRO%20sidebar%20pic.jpg" style="margin: 5px; float: left;" width="80" />Now in its second edition and with 10,711 copies sold, <em>Insider Secrets to Hydraulics </em>is the only book that deals with both the technical and the commercial issues involved in the maintenance, repair, and overhaul of hydraulic equipment. This means it not only covers preventative maintenance, fault-finding, component repair, and replacement; it also peels back the curtain on a number of ingrained industry practices that can increase the operating cost of hydraulic equipment. For more information and to order the book, visit <a href="http://HydraulicSupermarket.com" target="_blank">HydraulicSupermarket.com</a>.</p> <table border="0" cellpadding="0" cellspacing="0" width="570"> <tbody> <tr> <td width="41"> <img src="http://insidepenton.com/electronic_design/adobe-pdf-logo-tiny.png" /></td> <td style="padding-left: 0px;" width="459"> <a href="/datasheet/two-sound-reasons-use-multigrade-hydraulic-fluid-pdf-download">Download this article in .PDF format</a><br /> This file type includes high resolution graphics and schematics when applicable.</td> </tr> </tbody> </table> <p>&nbsp;</p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/hydraulic-fluids/two-sound-reasons-use-multigrade-hydraulic-fluid#comments Hydraulic Fluids Tue, 09 Dec 2014 16:56:00 +0000 29891 at http://hydraulicspneumatics.com From the Guy-To-Guy's Creed: You Can't Break What's Already Broken http://hydraulicspneumatics.com/blog/guy-guys-creed-you-cant-break-whats-already-broken <div class="node-body blog-body"><p>John Spathonis is an engineering manager with the Department of Transport and Main Roads, Queensland, Australia. He sent me this story about a Go-To-Guy, who influenced his career when he was a still wet-behind-the-ears apprentice:<br /> <br /> <em>&quot;George was a diesel mechanic and a very smart man. It was a shame but he was also deeply troubled as a result of the Vietnam War. Anyway, George was sent to do some emergency field repairs to a road grader that had broken down. It was important that the grader be put back into service as soon as possible. It eventuated that the cast iron casing of the power steering pump had cracked completely through on one side. I think the pump was external gear type. Please forgive my memory because this was about 30 years ago. </em></p> <p><em>With the main pressure housing cracked most mechanics would have given up, as a replacement pump was the only solution. But George was not your average mechanic. To keep the grader running for a few days, George did a quick fix. He skew drilled a hole in the housing across the crack and installed a bolt to hold the crack tightly together. To my admiration this worked (possibly lost a few drips of oil) and the grader was able to be used until a new pump was available. The lesson I learnt and have applied in my life ever since, is you cannot break something that is already broken. So give it a go.&quot;</em><br /> <br /> For those unfamiliar, Queensland is a huge and relatively sparsely populated state--especially 30 years ago. The broken down grader that George had to deal with was probably stuck in the middle of nowhere. Nearest town 200 miles away. And they get one delivery a week. On a Friday. And today&#39;s Saturday. This is just the sort of mission you want your #1 Go-To-Guy on: &quot;With the main pressure housing cracked most diesel mechanics would have given up...&quot;<br /> <br /> But not George. He knew there was nothing to lose: the pump was already broken. So he dared the skew-drill and bolt fix -- and won. Do you think George ever got laid off when the order came from above to reduce the head count? Nope. <a href="http://www.hydraulicsupermarket.com/whatever-it-takes.html">Like most Guy-To-Guys</a>, I&#39;d say George had a job with Main Roads for as long as he wanted it. And through his own &#39;can-do&#39; example, spawned many other Go-To-Guys within. Including I suspect, John who sent me this story.<br /> <br /> <strong>Bottom line</strong>: not attempting a band-aid fix on something that&#39;s already broken can be a mistake (within reason of course!). To discover six other costly mistakes you want to be sure to avoid with your hydraulic equipment, <a href="http://www.hydraulicsupermarket.com/track?p=handp&amp;w=smr"><strong>get &quot;Six Costly Mistakes Most Hydraulics Users Make... And How You Can Avoid Them!&quot; available for FREE download here</strong></a>.</p> </div> <div class="og_rss_groups"><ul class="links"><li class="og_links first last"><a href="/blog/hydraulics-work">Hydraulics At Work</a></li> </ul></div> http://hydraulicspneumatics.com/blog/guy-guys-creed-you-cant-break-whats-already-broken#comments Hydraulics At Work Tue, 09 Dec 2014 01:28:00 +0000 29881 at http://hydraulicspneumatics.com A Simple Way To Avoid 'Infant Mortality' Of Hydraulic Components http://hydraulicspneumatics.com/blog/simple-way-avoid-infant-mortality-hydraulic-components <div class="node-body blog-body"><p>A new client, a hydraulic repairer, consulted me about the failure of one of their piston pump rebuilds. The pump was not installed by them, but when the failed unit came back for inspection, it was obvious the drive coupling had been hammered onto the pump&#39;s drive shaft.<br /> <br /> For the uninitiated, this is a really dumb thing to do. If you ever come across a drive coupling that is tight on its shaft, do NOT reach for a hammer; reach for the emery paper and get busy with it. And this applies to any piece of rotating equipment, not just a hydraulic pump or motor.<br /> <br /> Of course, my client was interested to know what influence the battering of the pump&#39;s drive shaft may have had on its failure. And that&#39;s a rather long story for another time. But I mention it here because, separately, another client contacted me about getting a commissioning procedure or checklist they can hand out to their customers with every hydraulic component they rebuild.<br /> <br /> This is something all hydraulic repairers should do to avoid unnecessary &#39;infant mortalities&#39; and the warranty claims that usually result from them. It&#39;s also something I instigated at the hydraulic repair shop I was managing 15 years ago. And the use of checklists is something I advocate all hydraulic equipment users adopt in <strong><a href="http://www.hydraulicsupermarket.com/track?p=handp&amp;w=isthsp">Insider Secrets to Hydraulics</a></strong>.<br /> <br /> Checklists are a great tool for eliminating human error and have application in any situation where the cost of mistake or omission is significant. But there are a couple of important points with checklists when it comes to their effectiveness. The first, as I explained to my client who want&#39;s to include one with each hydraulic component they rebuild, is to be most effective they need to be machine specific. The pre-flight checklist for a Boeing 747 is no use to the pilot of an Airbus A340.<br /> <br /> Sure, you can cover the steps common to all situations, such as, in the case of a piston pump: &quot;fill the case with clean hydraulic oil through the uppermost drain port&quot;. But beyond that, there are so many different variants of pump installation, it&#39;s difficult - and potentially confusing, to try and cover all necessary steps, in a single, generic procedure.<br /> <br /> The other point is, the very best checklists are dynamic; they&#39;re a work in progress. A friend of mine, who is ex-military, uses a checklist before embarking on a camping trip with his family. Obviously, he does this so he doesn&#39;t leave any essential equipment at home. But he takes this one step further. When he returns from each trip, he updates his checklist - no only does he add to his list things he should have taken, he also removes from his list, things he did take but did not need.<br /> <br /> The point about this is, when you sit down to right a check list, it is difficult to foresee every eventually. Not only the things that should be done; but also the things that should not be done. My previous, pre-start checklists haven&#39;t included the instruction: &quot;Do NOT force the drive coupling onto the pump or motor shaft!&quot; But they will now. And so should yours.<br /> <br /> Bottom line: not using a checklist when starting or restarting a hydraulic system after maintenance work has been carried out can turn out to be an expensive mistake. To discover six other costly mistakes you want to be sure to avoid with your hydraulic equipment, get <em>&quot;Six Costly Mistakes Most Hydraulics Users Make... And How You Can Avoid Them!&quot;</em> <strong><a href="http://www.hydraulicsupermarket.com/track?p=handp&amp;w=smr">available for FREE download here</a></strong>.</p> </div> <div class="og_rss_groups"><ul class="links"><li class="og_links first last"><a href="/blog/hydraulics-work">Hydraulics At Work</a></li> </ul></div> http://hydraulicspneumatics.com/blog/simple-way-avoid-infant-mortality-hydraulic-components#comments Hydraulics At Work Mon, 01 Dec 2014 21:37:00 +0000 29861 at http://hydraulicspneumatics.com The RIGHT Way To Do Offline Filtration On Hydraulic Systems http://hydraulicspneumatics.com/blog/right-way-do-offline-filtration-hydraulic-systems <div class="node-body blog-body"><p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/HPBlogWeb.jpg" style="width: 595px; height: 397px;" title="Certainly, water or particulate contamination doesn't normally necessitate an oil change. These contaminants can be filtered out. (Image courtesy of Thinkstock)" /></p> <p>A very frustrated <a href="http://www.hydraulicsupermarket.com/pro-club.html" target="_blank">Hydraulics Pro Club</a> member sent me this recently:<br /> <br /> <em>&quot;I have done all but beg the company I work for to buy a portable oil filtration caddy but I cant seem to get my point across to them. The company is a government contractor and everything is done on a cost basis at the moment. So it&#39;s cheaper to mix oils today because they got a &#39;deal&#39; on oil, or it&#39;s cheaper to change oil than it is to buy an offline filtration system, or most parts are cheaper than the filtration system, or the worst excuse I&#39;ve been given so far is &#39;we have a lot of oil, no need to filter it&#39;! Nevertheless, I will win this battle eventually and so I am looking for the proper procedure to filter the fluid in a hydraulic system.&quot;</em><br /> <br /> This is a great example of being penny wise and dollar foolish. And of what happens when bean counters or managers with no technical knowledge are allowed to run the show. As you might expect under this management regime, another major point is being missed as well. That is: why are we changing the oil?<br /> <br /> Certainly, water or particulate contamination doesn&#39;t normally necessitate an oil change. These contaminants can be filtered out. But offline filtration is not a cure for all the ailments that can afflict the oil either.<br /> <br /> Like a doctor treating a sick patient, a diagnosis is required before the correct treatment can be prescribed. So plugging-in a filter cart once a week, month or year, without any signs or symptoms of an illness, is over-servicing. And like taking antibiotics when you&#39;re not sick, it won&#39;t do any harm, but it&#39;s an unnecessary waste of money.<br /> <br /> If you follow this logic, even though this member&#39;s intentions are sound, he&#39;s putting the cart before the horse (no pun intended). The logical first step would be to convince his masters to set up an oil analysis program. Done right, this will provide all the information required to manage the oil in the most cost effective way.</p> <div class="related-content"> <div class="related-label"> Related</div> <p><a href="/blog/4-ways-make-your-hydraulic-oil-last-longer">4 Ways to Make Your Hydraulic Oil Last Longer</a></p> <p><a href="/blog/3-big-problems-caused-hot-running-hydraulics">3 BIG Problems Caused By Hot-Running Hydraulics</a></p> <p><a href="/blog/tried-true-ways-dealing-air-hydraulic-fluid">Tried &amp; True Ways of Dealing with Air in Hydraulic Fluid</a></p> </div> <p>He will then know when to plug-in the filter cart and what he&#39;s got to remove. Is it hard particles, soft particles (varnish and sludge) and/or water? And just as importantly, he&#39;ll know when there is no point plugging in the filter cart any more - because the oxidative life of the oil is used up or the additives are depleted. Just as there is no point flogging a dead horse, there&#39;s no point filtering dead oil.<br /> <br /> And when it is time to plug in the filter cart, subsequent oil analysis - or at least a particle count - is the only scientific way to know when to switch it off. With all this said, what steps should be followed when filtering the oil?<br /> <br /> Assuming a portable filter cart is being used, it should be connected to the hydraulic reservoir in such a way that its inlet and return are as far away from each other as possible. Ideally, the oil should be at operating temperature with the system functioning. This ensures exchange of the oil in the tank with that in the system.<br /> <br /> The time it will take to clean-up the oil will depend on the type and concentration of the contaminants, the volume of the hydraulic system and the capacity of the filter cart.As already mentioned, the oil should be filtered until oil analysis reveals that the target cleanliness has been achieved. But as a general rule of thumb, the total volume of oil in the system should pass through the filter cart a minimum of 7 times.<br /> <br /> For example, say we have a hydraulic system with a 100 gallon reservoir. We plan to have the filter cart running while the hydraulic system is operational and we estimate there is a further 40 gallons in the rest of the system. So the total oil volume is 140 gallons. If our filter cart has a flow rate of 0.5 gallons per minute, then based on the 7 times rule, the filtration time would be calculated as follows:<br /> <br /> 7 x 140 = 980 gallons<br /> <br /> 1540/0.5 = 1960 minutes or 32.6 hours<br /> <br /> Clearly, in this example a bigger filtration cart would be nice. Although in an industrial application, a filtration time of this duration is probably acceptable. Keep in mind this is a thumb rule only and the ultimate determinant of success is when oil analysis confirms it.<br /> <br /> <strong>Bottom line</strong>: plugging in a filter cart when it&#39;s not necessary or not constructive is a mistake. To discover six other costly mistakes you want to be sure to avoid with your hydraulic equipment, <a href="http://www.hydraulicsupermarket.com/track?p=handp&amp;w=smr" target="_blank">get &quot;Six Costly Mistakes Most Hydraulics Users Make... And How You Can Avoid Them!&quot; available for FREE download here</a>.</p> <p>&nbsp;</p> </div> <div class="og_rss_groups"><ul class="links"><li class="og_links first last"><a href="/blog/hydraulics-work">Hydraulics At Work</a></li> </ul></div> http://hydraulicspneumatics.com/blog/right-way-do-offline-filtration-hydraulic-systems#comments Hydraulics At Work Mon, 24 Nov 2014 21:45:00 +0000 29851 at http://hydraulicspneumatics.com A Look at Hydraulic Hose Failures http://hydraulicspneumatics.com/blog/look-hydraulic-hose-failures <div class="node-body blog-body"><p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/HydraulicHoseWeb.jpg" style="width: 300px; height: 195px; float: left;" />We regularly look at what types of articles draw the most visitors on our websites. One of the biggies is maintenance. What&#39;s interesting about maintenance of hydraulic systems is that even though many of the tools and instruments have changed dramatically during my 25+ years on H&amp;P, many of the problems and their solutions are still the same.</p> <p>Probably the most frequent cause of hydrauic system malfunctions continues to be contamination. But another is misapplication of products, especially hose. Hydraulic hose is really tough, and it seems to be almost indestructible when new. But after being subjected to the rigors of hydraulic pressure, flow, high temperatures, and wide swings in all these, hoses can suffer premature failure if not applied, routed, and installed properly.</p> <div class="related-content"> <div class="related-label"> Related</div> <p><a href="/blog/hydraulic-conductor-face-hose-vs-tube">Hydraulic Conductor Face Off: Hose vs Tube</a></p> <p><a href="/hose-tubing/hose-family-aims-simplicity">Hose Family Aims at Simplicity</a></p> <p><a href="/hose-tubing/flak-jacket-hose">A Flak Jacket for Hose</a></p> </div> <p>If you&#39;re faced with a hose that is leaking or, worse yet, started coming apart, how do you know what the cause is? Discovering what wnent wrong can be a big step in preventing future failures. Detailed fialure analysis should be left to experts, but sometimes seeing the results of misapplication or improper installationg will aid understanding of why manfacturers have developed their recommendations.</p> <p>I found an article that does just this. It covers more than a dozen hose failures, explains what the problem is, what caused it, and how to prevent it in the future. <strong><a href="/hose-tubing/guide-recognizing-causes-hose-failure" target="_blank">Click here</a></strong> to view the article.</p> <p>The key to preventing these premature failures, of course, is training. We have dozens of articles on our website describing proper application, routing, and installation of hydraulic hose.</p> </div> <div class="og_rss_groups"><ul class="links"><li class="og_links first last"><a href="/blog/hitch-post">The Hitch Post</a></li> </ul></div> http://hydraulicspneumatics.com/blog/look-hydraulic-hose-failures#comments Maintenance Hose & Tubing The Hitch Post Sun, 23 Nov 2014 04:40:00 +0000 29841 at http://hydraulicspneumatics.com Wally O'Brien: 1950 - 2014 http://hydraulicspneumatics.com/news/wally-obrien-1950-2014 <div class="node-body article-body"><p><a href="/site-files/hydraulicspneumatics.com/files/uploads/2014/12/Wally O2.jpg" target="_blank"><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/12/Wally%20O2.jpg" style="width: 200px; margin-left: 4px; margin-right: 4px; float: right; height: 275px;" /></a>Wallace &ldquo;Wally&rdquo; Arthur O&rsquo;Brien, 64, of Wolfeboro, N. H., died Nov. 15, 2014 at Massachusetts General Hospital in Boston. Born Sept. 11, 1950 in Elizabeth, N. J., he earned a BS in Marketing/Advertising from Ferris State University and later served as a media representative for <em>Hydraulics &amp; Pneumatics</em> magazine for New England and the east coast from 1986 until 2011. In 2012, he and his wife moved to Wolfeboro when they purchased the 1810 House and operated it as a bed and breakfast and antique barn.</p> <p>In addition to his family, Wally had a love of music, fixing antique cars, antiquing, boating, and, tapping into his sense of humor for a good pun. Survivors include his wife, Connie, daughter, Heather (Joseph) Alterieri, son, Christopher (Sarah), two grandchildren; and brother, Forrest (Jeanne) O&rsquo;Brien.</p> <p><strong><a href="http://www.baker-gagnefuneralhomes.com/fh/obituaries/obituary.cfm?o_id=2808745&amp;fh_id=12957" target="_blank">Click here</a></strong> to view the local obituary and view or sign guest book.</p> <p>Donations can be made in Wally&rsquo;s name to the Amyloid Research Fund by <strong><a href="http://www.bu.edu/amyloid/donate/form/" target="_blank">clicking here</a></strong>.</p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/news/wally-obrien-1950-2014#comments News Sat, 22 Nov 2014 00:15:00 +0000 29871 at http://hydraulicspneumatics.com How to Avoid Hydraulic Accumulator Failure http://hydraulicspneumatics.com/blog/how-avoid-hydraulic-accumulator-failure <div class="node-body blog-body"><p>When properly applied in a hydraulic circuit, bladder and diaphragm accumulators can have a long and trouble-free life. But if their operating parameters are not correct, recurring failure can result. Consider this story from a <a href="http://www.hydraulicsupermarket.com/pro-club.html">Hydraulics Pro Club</a> member:<br /> <br /> <em>&quot;Currently we are using a miniature accumulator from Hawe -- part number AC 130-1/4, max. operating pressure 500 bar, max. gas fill (nitrogen) 250 bar, with a rated volume of 13 cm3. We charge these accumulators to 6 bar and use them on a circuit with 9 bar supply pressure. These circuits are used to test the control pressure on variable solenoids in a transmission control module. We are using Dextron 6 ATF for our hydraulic fluid. We have 8 testers that have 6 of these accumulators on them - 48 accumulators total with more testers to come in the near future. My problem is that we have to replace about 3 accumulators a week because they have ruptured. Is there something I can do to fix this problem?&quot;</em><br /> <br /> There are a couple of things which should be checked when a bladder or diaphragm accumulator fails. The first is compression ratio. If the bladder or diaphragm is subject to excessive deformation when the accumulator is pressurized to maximum system pressure, the life expectancy of the bladder or diaphragm is greatly reduced.<br /> <br /> Compression ratio is calculated by dividing the maximum pressure of the system or sub-system in which the accumulator is installed (P2), by its gas pre-charge pressure (P0).<br /> <br /> In the example above, P2 = 9 bar and P0 = 6 bar, so the compression ratio for the application is P2/ P0 = 9/6 = 1.5 to 1. The permissible compression ratio for a bladder accumulator is typically 4 to 1 and 6 to 1 for diaphragm units, so this is well within acceptable limits. A quick look at the data sheet for a Hawe AC 130-1/4 accumulator confirms this. The AC 130-1/4 is a diaphragm accumulator with an allowable compression ratio of 4 to 1.<br /> <br /> The next thing to check is that the actual gas precharge pressure is correct. Depending on the application of the accumulator, precharge pressure (P0) is typically 0.6 to 0.9 of the minimum pressure of the system or sub-system in which the accumulator is installed (P1).<br /> <br /> From a reliability perspective, the reason why P0 must always be less than P1 is so that the accumulator is never completely emptied of fluid during normal operation. If all fluid is discharge from the accumulator at minimum system pressure (P1) there is a risk of the bladder or diaphragm being damaged by the anti-extrusion device. This is a device which is designed to stop the bladder or diaphragm entering the accumulator&#39;s discharge port.<br /> <br /> In practice this means that if minimum system pressure (P1) is changed for any reason, pre-charge pressure (P0) must also be changed. And if P0 is changed, the compression ratio, P2/ P0 should be re-checked.<br /> <br /> In the example above, we&#39;re told that P0 = 6 bar and P2 = 9 bar, but we&#39;re not told what P1 is. However, by reverse calculation we can say that if minimum system pressure falls below 6.7 bar, then the diaphragm is at risk of being damaged due to complete discharge of fluid from the accumulator.<br /> <br /> Another consideration in the above application is operating temperature. Accumulator bladders/diaphragms are made from polymers, and the life of all polymeric materials is reduced exponentially by operating temperatures which exceed 80&deg;C.<br /> <br /> We&#39;re not told what the fluid operating temperature is during testing, but given this is an automatic transmission test rig, and automatic transmissions can operate with peak temperatures as high as 150&deg;C (300&deg;F), this is much higher than what is typical or ideal for a conventional hydraulic system. So excessive operating oil temperature may also be a factor in diaphragm failure in this case.<br /> <br /> And while on the subject of temperature extremes, remember when charging the gas end of a bladder or diaphragm accumulator, the nitrogen gas should always be admitted very SLOWLY. If the high pressure nitrogen is allowed to expand rapidly as it enters the bladder, it can chill the bladder&#39;s polymer material to the point where immediate brittle failure occurs. Rapid precharging can also result in the bladder or diaphragm being damaged by the anti-extrusion device.<br /> <br /> Bottom line: failing to consider your accumulator&#39;s permissible compression ratio and the relative values of P0, P1 and P2 is a mistake. To discover six other costly mistakes you want to be sure to avoid with your hydraulic equipment, <a href="http://www.hydraulicsupermarket.com/track?p=handp&amp;w=smr">get &quot;Six Costly Mistakes Most Hydraulics Users Make... And How You Can Avoid Them!&quot; available for FREE download here</a>.</p> </div> <div class="og_rss_groups"><ul class="links"><li class="og_links first last"><a href="/blog/hydraulics-work">Hydraulics At Work</a></li> </ul></div> http://hydraulicspneumatics.com/blog/how-avoid-hydraulic-accumulator-failure#comments Hydraulics At Work Mon, 17 Nov 2014 21:31:00 +0000 29821 at http://hydraulicspneumatics.com Ameripride Takes Delivery of First Hydraulic Hybrid Truck http://hydraulicspneumatics.com/rail-truck-bus/ameripride-takes-delivery-first-hydraulic-hybrid-truck <div class="node-body article-body"><div> <p style="margin-left: 5pt;">Earlier this month <strong><a href="http://www.ameripride.com" target="_blank">AmeriPride Services Inc.</a></strong>, one of the largest uniform and linen supply companies in North America, took delivery of its first&nbsp; truck that uses a fuel-efficient hydraulic hybrid. &nbsp;The vehicle, a 2014 Ford F59 chassis with a Morgan Olson Route Star walk-in van body, will be put into delivery service in one of its Canadian Linen branches in Toronto. &nbsp;AmeriPride, Minnetonka, Minn., selected <strong><a href="http://lightninghybrids.com/" target="_blank">Lightning Hybrids</a></strong> to provide the hybrid systems that are expected to significantly reduce fuel consumption, reduce brake maintenance costs and cut emissions. AmeriPride provides linen, uniforms, floor mats, restroom and cleaning products to nearly 150,000 customers every week.</p> <p style="margin-left: 5pt;"><a href="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/Lightning truck.jpg"><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/Lightning%20truck.jpg" style="width: 333px; height: 201px; float: right; margin-left: 4px; margin-right: 4px;" title="This truck is the first hydraulic hybrid in AmeriPride’s fleet of approximately 1,900 vehicles in North America. It will achieve better fuel economy than a comparable non-hybrid vehicle by capturing, storing and re-using the braking energy that is normally wasted in non-hybrid vehicles. In addition, the hybrid version puts out fewer emissions and brake particulates, advancing AmeriPride’s clean operations and commitment to the environment." /></a>This truck, the first hydraulic hybrid in AmeriPride&rsquo;s fleet of approximately 1,900 vehicles in North America, will achieve better fuel economy than the comparable non-hybrid vehicle because it captures, stores and re-uses the braking energy which is normally wasted in the conventional, non-hybrid vehicle. &nbsp;In addition, the hybrid is cleaner, emitting lower emissions and brake particulates, furthering AmeriPride&rsquo;s clean operations and commitment to the environment.</p> <p style="margin-left:5.0pt;"><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/Keegan.jpg" style="width: 100px; height: 125px; float: left; margin-left: 4px; margin-right: 4px;" title="Keegan" />&ldquo;Testing this hydraulic hybrid is a part of a larger company initiative to reduce energy consumption and our carbon footprint,&rdquo; said Brian Keegan, SVP of Plant Operations and Supply Chain for AmeriPride Services and Canadian Linen. &ldquo;Last year our company launched a pilot program to test compressed natural gas, propane and plug-in electric vehicles in an effort to positively impact the environment and assess the impact on the company&rsquo;s overall operations.&rdquo;</p> <p style="margin-left:5.0pt;">The company has already replaced many of its cargo vans with fuel-efficient sedans and reconfigured most of its service routes to reduce mileage. It has also incorporated better internal controls to reduce idling and speeding and implemented better training and communication with drivers to increase awareness and promote behavioral change. AmeriPride also acquired several double-decker semi-truck trailers that have twice the cargo capacity and will greatly reduce fuel and emissions.</p> </div> <h3> Outfitting with hybrid hydraulics</h3> <p style="margin-left:5.0pt;">The system from Lightning Hybrids, Loveland, Colo.,was installed at the <strong><a href="http://www.morganolson.com" target="_blank">Morgan Olson</a></strong> facility in Sturgis, Mich. Morgan Olson supplies more walk-in van to the textile rental industry than any other manufacturer in North America. Larry Palmer, Morgan Olson&rsquo;s Director of Fleet Sales states: &ldquo;More large fleets are interested in these new fuel saving technologies, and Morgan Olson is leading the way to incorporate these systems into our walk-in van builds. We&rsquo;ve built our legendary walk-in vans on every new technology from electric to CNG (compressed natural gas) and propane, and we believe hydraulic hybrids are another way to reduce emissions and increase fuel savings. We&rsquo;re looking forward to working with Lightning Hybrids and our loyal partners at AmeriPride.&rdquo;</p> <p style="margin-left:5.0pt;"><a href="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/Lightning undercarriage web.jpg" target="_blank"><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/Lightning%20undercarriage%20web.jpg" style="width: 300px; float: left; margin-left: 4px; margin-right: 4px; height: 169px;" title="View of truck's undercarriage shows major components of hybrid hydraulic system.(Click on image for larger view.)" /></a>Lightning Hybrids designs and manufactures hybrid systems for medium and heavy duty fleet vehicles. &nbsp;The system provides fuel efficiency by regenerating braking energy, provides safer braking and more power for acceleration, and decreases greenhouse gas emissions. The Lightning Hybrids system does not have any batteries, instead safely and efficiently storing energy mechanically in composite hydraulic accumulators, which are a fraction of the cost and weight of batteries.</p> <p style="margin-left:5.0pt;">The composite accumulators, manufactured by <strong><a href="http://steelheadcomposites.com/" target="_blank">Steelhead Composites</a></strong>, Golden, Colo., consist of an aluminum tank wrapped with spun carbon fiber, a rubber compression bladder and ports for fluid flow. The carbon fiber shell is about one fourth the weight of the industry-standard steel shell of equal size. For example, 15-gal carbon fiber accumulator weighs 115 lb, whereas a 15-gal steel accumulator weighs 465 lb. The system can be installed on new vehicles or retrofitted on vehicles already in service. &nbsp;It is sold through a network of dealers and upfitters.</p> <div> <p style="margin-left:5.0pt;"><a href="https://www.youtube.com/watch?v=m87sAql-s2w&amp;feature=youtu.be" target="_blank"><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/Vid%20capture.png" style="width: 200px; height: 111px; float: right; margin-left: 4px; margin-right: 4px;" title="Click on image to view an animated video showing how the Lightning Hybrids system operates." /></a>&ldquo;We are very excited to launch this project with AmeriPride and Morgan Olson,&rdquo; stated David Brosky, Vice President of Sales for Lightning Hybrids. &nbsp;&ldquo;Both companies are proving to be very committed and engaged early adopters of our hybrid technology and they both share our strong commitment to improve the energy efficiency and lower the emissions of vocational trucks.&rdquo;</p> <p style="margin-left:5.0pt;">Lightning Hybrids currently has several systems operating in fleets around the world and expects significant growth in the next quarter and beyond. &nbsp;The system is made and assembled in Loveland, Colo. at Lightning&rsquo;s advanced manufacturing and engineering facilities. For more information, visit <strong><a href="http://www.lightninghybrids.com/">www.lightninghybrids.com</a></strong>.</p> <p style="margin-left:5.0pt;"><strong><a href="/search/results/lightning%20hybrids" target="_blank">Click here</a></strong> to see a list of more than a dozen hyperlinks to articles we&#39;ve published on hybrid hydraulic systems from Lightning Hybrids.</p> <p style="margin-left:5.0pt;"><strong><a href="https://www.youtube.com/channel/UCbkcbbBzG1LOf_q1xS_RMYA" target="_blank">Click here </a></strong>to visit Lightning Hybrids&#39;s YouTube channel.</p> </div> <p>&nbsp;</p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/rail-truck-bus/ameripride-takes-delivery-first-hydraulic-hybrid-truck#comments Accumulators Rail, Truck & Bus Fri, 14 Nov 2014 15:27:00 +0000 29801 at http://hydraulicspneumatics.com Electrohydraulic Proportional Valve Tolerates Heavy Shock http://hydraulicspneumatics.com/hydraulic-valves/electrohydraulic-proportional-valve-tolerates-heavy-shock <div class="node-body article-body"><p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/RL95-A.jpg" style="width: 595px; height: 365px;" /></p> <p>Series TEB proportional valves from <a href="http://www.atos.com" target="_blank">Atos Spa</a>, Sesto Calende, Italy, use digital control, making them impervious to the EMI and RFI that can plague analog devices. The valve is constructed to withstand shock of up to 50 g.</p> <p>Sized at 06 and 10 for direct operation and 10, 16, 25, and 32 for pilot operation for pressures to 350 bar (5,080 psig). Features include factory-preset, on-board electronics and control software for setting of scale, bias, linearization and dynamic response. The valve accepts a &plusmn;10-V or 4- to 20-mA input signal, works within temperatures from &ndash;40&deg; to 60&deg; C (&ndash;40&deg; to 140&deg; F), and it meets IP66 and IP67 requirements for water- and dust-tight enclosure.</p> <p>For more information, <a href="http://bit.ly/HP1411-AtosTEB" target="_blank">view or download</a> a PDF of the datasheet on the product.</p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/hydraulic-valves/electrohydraulic-proportional-valve-tolerates-heavy-shock#comments Hydraulic Valves Thu, 13 Nov 2014 19:05:00 +0000 29781 at http://hydraulicspneumatics.com Hydraulics Essential to Mobile Forklift http://hydraulicspneumatics.com/material-handling/hydraulics-essential-mobile-forklift <div class="node-body article-body"><p>Unless you work in the material handling or shipping industry, you probably think of a forklift as 4-wheeled vehicle that zips through warehouses unloading pallet-mounted cargo from trucks, loading cargo onto trucks, or moving freight around a warehouse to make room for more freight. Though this is an accurate description of the traditional warehouse forklift truck, more and more vehicles are moving from this convention to the truck-mounted, all-terrain forklift.</p> <table border="0" cellpadding="0" cellspacing="0" width="570"> <tbody> <tr> <td width="41"> <img src="http://insidepenton.com/electronic_design/adobe-pdf-logo-tiny.png" /></td> <td style="padding-left: 0px;" width="459"> <a href="/datasheet/hydraulics-essential-mobile-forklift-pdf-download">Download this article in .PDF format</a><br /> This file type includes high resolution graphics and schematics when applicable.</td> </tr> </tbody> </table> <p>Two applications have driven this diversity in forklift truck design. First, outdoor warehousing has become commonplace, so the traditional 4-wheel truck with small tires and rear drive and steering proves unsuitable in many situations. Instead, forklift trucks that can tackle uneven terrain were developed to serve this need. Second, many companies need to load or unload cargo at facilities that have no forklift truck. For these cases, the lift truck is loaded onto the truck bed and transported with the freight to the destination. Once there, the lift truck lowers itself to the ground, then it moves the freight from the truck&rsquo;s cargo bed to a specific area at the destination.</p> <p>One particular model combines both of these features and more&mdash;all made possible by the innovative use of hydraulics. The lift truck features a 2-wheel hydrostatic drive (3-wheel optional) that not only provides propulsion, but speed control and braking as well. Steering is accomplished through a rear-mounted wheel that is positioned by a rotary actuator. As with most forklift trucks, the mast assembly is raised and lowered using hydraulics. But, in addition, this model incorporates a reach mechanism that is, essentially, a horizontally mounted double scissors jack. A pair of hydraulic cylinders actuates this mechanism to permit the fork assembly to reach loads positioned up to four feet in front of the lift truck.</p> <p><strong>HST Provides Propulsion and Safety</strong></p> <p>The hydraulic system of the lift truck is powered by a 46-hp (@2700 rpm) diesel engine driving an axial-piston pump for the hydrostatic transmission (HST). A tandem-mounted gear pump provides flow for steering, the mast assembly, and stabilizers. In the HST circuit, the variable-displacement pump delivers up to 46 cc/rev (2.8 in.<sup>3</sup>/rev) and has a maximum pressure rating of 350 bar (5000 psi). Output flow from the pump is routed to a parallel circuit feeding a pair of 35 cc/rev (2.14 in.<sup>3</sup>/rev) fixed-displacement, axial-piston motors. Each motor is connected through a splined shaft to a planetary wheel drive to rotate the front wheels at high torque.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/TrailerMate-50A.jpg" style="width: 595px; height: 393px;" title="An all-terrain truck-mounted forklift boasts many hydraulically powered features that give a big boost to productivity. One such feature is its reach mechanism, which can engage a load placed on the far side of a truck bed." /></p> <p>The HST also incorporates a traction control system that can be engaged when the lift truck is operated under conditions that prevent the tires from getting good traction. The operator activates the traction control system through a switch, which routes hydraulic fluid through a flow divider-combiner. With the system activated, the divider-combiner valve routes hydraulic fluid equally to both wheels. This prevents the wheel with lower traction from spinning&mdash;often referred to as positraction.</p> <p>Using the HST simplifies the design by providing not only propulsion, but braking as well. This eliminates the need for the many braking components that would otherwise be necessary if the vehicle used a mechanical drive. A spring-applied/pressure-released brake holds the lift truck in place when it is parked. A switch on the parking brake is wired to the engine&rsquo;s electrical circuit to keep the engine from starting unless the brake is applied.</p> <p><strong>Rotary Actuator Simplifies Steering</strong></p> <p>Steering is accomplished though a third wheel mounted in the center-rear of the vehicle. (As an option, this wheel incorporates an axial-piston motor to provide 3-wheel drive.) This rotary actuator uses a piston-and-helix configuration to generate high torque through a full 180&deg; rotation. The rotary actuator offers several advantages over a conventional steering cylinder and linkage setup. The rotary actuator:</p> <p>&bull; eliminates mechanical linkages and the maintenance associated with them<br /> &bull; exhibits constant steering effort throughout the full range of steering<br /> &bull; needs no periodic adjustment for wear<br /> &bull; achieves longer life<br /> &bull; is more compact<br /> &bull; provides more precise steering control</p> <div class="related-content"> <div class="related-label"> Related</div> <p><a href="http:///hydraulicspneumatics.com/200/TechZone/HydraulicValves/Article/False/87465/TechZone-HydraulicValves">Hydraulic valve module makes forklifts more efficient</a></p> <p><a href=" http://hydraulicspneumatics.com/200/IndZone/MaterialHandlin/Article/False/85202/IndZone-MaterialHandlin">Staged modulation improves forklift brake control</a></p> <p><a href=" http://hydraulicspneumatics.com/material-handling/no-substitute-safety">NO substitute for safety</a></p> </div> <p>In addition to these benefits of using rotary actuators, the lift truck takes advantage of the rotary actuator&rsquo;s pivot-style mounting. This mounting design incorporates integral bearings and a heavy-duty shaft and flange assembly, making it a self-contained steering actuator and wheel mount. Installation simply involves connecting the wheel assembly at the bottom, bolting the top flange of the actuator to the underside of the vehicle frame, and connecting the hydraulic lines.</p> <p>An engineer for the lift truck manufacturer pointed out that precise steering control is important because designers wanted the vehicle to be easy to use. This is one reason why they decided against using a skid-steer drive arrangement. With skid-steer, steering is accomplished by varying the speed of the wheels on the left or right side of the vehicle.</p> <p>In fact, rotating wheels forward on one side of the vehicle and in reverse on the other side allows the vehicle to turn on its own center. But because most operators would be accustomed to operating a conventional forklift truck, designers wanted their vehicle to have the steering feel of a conventional forklift. With the rear wheel positioned perpendicular to the front wheels, the Trailer Mate exhibits a turning radius of only 114 in., or 93 in. for the optional 3-wheel-drive model.</p> <p><strong>Far-Reaching Versatility</strong></p> <p>One of the most useful features of the lift truck is its reach mechanism. Essentially, this is a horizontally mounted scissors jack powered by a pair of hydraulic cylinders that extends the forks forward up to 48 in. This allows the vehicle to unload a truck entirely from one side of its cargo bed. Not only does this increase productivity, but it also improves safety because operators don&rsquo;t have to venture out onto the traffic side of a truck to unload it. Also, if an operator needs to reach a loaded pallet that lies behind another one, he or she can extend the forks forward and above the obstacle to gain access to the load without having to move the pallet that&rsquo;s in the way.</p> <table border="0" cellpadding="0" cellspacing="0" width="570"> <tbody> <tr> <td width="41"> <img src="http://insidepenton.com/electronic_design/adobe-pdf-logo-tiny.png" /></td> <td style="padding-left: 0px;" width="459"> <a href="/datasheet/hydraulics-essential-mobile-forklift-pdf-download">Download this article in .PDF format</a><br /> This file type includes high resolution graphics and schematics when applicable.</td> </tr> </tbody> </table> <p>The lift truck is also designed for ease of maintenance, especially the hydraulic system. All hydraulic connections use O-ring face seal fittings to prevent leakage and simplify removal and replacement of components. To ensure reliability, the hydraulic system incorporates 2-&micro;m filters in the HST circuit because it uses a piston pump and motors. Other circuits use a more dirt-tolerant gear pump, so 10-&micro;m filtration has proven adequate. In addition, all maintenance checks can be performed from the right-hand side of the vehicle.</p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/material-handling/hydraulics-essential-mobile-forklift#comments Material Handling Other Industries Thu, 13 Nov 2014 16:52:00 +0000 29761 at http://hydraulicspneumatics.com Troubleshooting Challenge: Unexpected pressure loss while testing a new hydraulic power unit http://hydraulicspneumatics.com/hydraulic-pumps-motors/troubleshooting-challenge-unexpected-pressure-loss-while-testing-new-hydrauli <div class="node-body article-body"><p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/Troubleshooting1.jpg" style="width: 266px; height: 199px; float: right;" />When I was manager of a large hydraulic power unit (HPU) fabrication shop, we had a strange problem while testing a large HPU. It consisted of a large vane pump, a pilot-operated relief, and a 5-bank D08 manifold with 3-position blocked center directional valves with pressure reducing modules. All the <em>A</em> and <em>B</em> ports contained pressure gauges. The HPU had a separate off-line filtration and cooling circuit, which we commonly refer to as a kidney loop. The pump was driven by a 100-hp, 1800-rpm electric motor &mdash; a large HPU, but a fairly simple system.</p> <p>The system pressure was set to 2250 psig with an output flow of 75 gpm. The pump would run for 30 to 60 seconds at a time under pressure, but then all pressure would quickly drop to near 0 psig for 2 to 3 seconds. Pressure would then quickly jump back up to 2250 psig. This happened 15 to 20 times before the test mechanic called me for help.</p> <p>The unit piping had about &frac12;-in. NPT and &frac12;-in. O-ring connections. No Teflon tape was used, just white, paste-type pipe dope for sealing the NPT connections. We felt the only valve that could cause the malfunction was the pilot-operated relief, so we dis-assembled and inspected it. We did this at least four or five times and could not see any contamination or sticking problem.</p> <p>We were pressed to move onto other units on the test stand, so we drained the oil from the reservoir and removed its access panels, with the eventual plan of retesting it later. However, we noticed that the reservoir bottom was covered with typical construction debris and a rather large amount of small beads of excess pipe dope.</p> <p><em>Any idea what was causing the problem?</em></p> <table border="0" cellpadding="0" cellspacing="0" width="570"> <tbody> <tr> <td width="41"> <img src="http://insidepenton.com/electronic_design/adobe-pdf-logo-tiny.png" /></td> <td style="padding-left: 0px;" width="459"> <a href="http://hydraulicspneumatics.com/datasheet/troubleshooting-challenge-unexpected-pressure-loss-while-testing-new-hydraulic-power-unit-">Download this article in .PDF format</a><br /> This file type includes high resolution graphics and schematics when applicable.</td> </tr> </tbody> </table> <p><strong>Solution to last month&rsquo;s problem: <a href="http://hydraulicspneumatics.com/cylinders-actuators/troubleshooting-challenge-hydraulic-system-causes-structural-failure" target="_blank">Hydraulic system causes structural failure</a></strong></p> <p><a href="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/Figure.gif" target="_blank"><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/Figure.gif" style="width: 266px; height: 330px; float: right; margin-left: 4px; margin-right: 4px;" title="Click on image for larger view." /></a></p> <p>The circuit design was intended to have the same speed lifting and lowering. The designer used a pressure and temperature-compensated flow control with 4-check valves arranged similar to an electrical &ldquo;Diode bridge.&rdquo; This always directed the oil flow coming from either direction through the flow control&rsquo;s entry port. One of the checks failed open due to a contamination problem and allowed the oil to bypass the flow control and consequenty drop 60,000 pounds of steel coil 18&rdquo; to a sudden stop.</p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/hydraulic-pumps-motors/troubleshooting-challenge-unexpected-pressure-loss-while-testing-new-hydrauli#comments Hydraulic Pumps & Motors Thu, 13 Nov 2014 16:16:00 +0000 29741 at http://hydraulicspneumatics.com Sensing Decisions Under Pressure http://hydraulicspneumatics.com/controls-instrumentation/sensing-decisions-under-pressure <div class="field-byline"> Ketan Mehta, Honeywell Sensing &amp; Control Group </div> <div class="field-deck"> Important considerations must be weighed when specifying pressure sensors for pneumatic systems. </div> <div class="node-body article-body"><table border="0" cellpadding="0" cellspacing="0" width="570"> <tbody> <tr> <td width="41"> <img src="http://insidepenton.com/electronic_design/adobe-pdf-logo-tiny.png" /></td> <td style="padding-left: 0px;" width="459"> <a href="/datasheet/sensing-decisions-under-pressure-pdf-download">Download this article as a PDF file.</a><br /> This file type includes high resolution graphics and schematics when applicable.</td> </tr> </tbody> </table> <p>Pressure sensors are the gateway between the physical world of pneuamtics and the electrical world of control systems. Designed to operate accurately and reliably in harsh environments for years, or even decades at a time, pressure sensors typically only garner attention when they fail, which is a rare occurrence. Smart designers know that paying close attention to these devices is necessary to ensure that the switch or transducer they choose delivers the optimal combination of performance, reliability, and solution cost for their particular application.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/Automate-LEAD_0.jpg" style="width: 595px; height: 410px;" title="Many manufacturing systems, such as the blow-molding operation for plastic bottles, extensively use pneumatic switches and sensors to monitor and control the mechanisms that assemble or form a product and transport it down the line. (Image courtesy of Paula Hynes, Rodon Group)" /></p> <p>Even though only a handful of basic types of sensors exist, the selection process isn&rsquo;t as easy as it might seem. Each type of pressure switch or transducer is available in a near-infinite combination of packages, ports, pressure ranges, electrical outputs, and connector styles, which can make selecting the best match for a particular job a challenging, time-consuming feat. The goal of this article is to familiarize you with pressure-sensor functionality and construction, and how that affects a particular pressure sensor&rsquo;s suitability for a given application.</p> <h3> Pressure Sensors in Pneumatic Systems</h3> <p>Pressure-sensing devices play critical roles in pneumatic and hydraulic systems, whether helping to control a high-speed manufacturing system or monitoring various inlet and outlet pressures within an air compressor to determine performance and efficiency.</p> <p>Industrial machines and manufacturing systems rely on pneumatic switches and transducers for information that enables them to move precisely and apply the required amount of force or torque.</p> <p>Pressure-sensing devices can be categorized as either a switch or transducer. Pressure switches, relatively simple devices, indicate whether the pressure they&rsquo;re sensing is above or below a predetermined threshold. Their output represents a change in the state of either an on-off switch or a two-state electrical signal.</p> <p>A typical pressure switch consists of a contact driven by a diaphragm or piston, which is pushed in one direction by the fluid being sensed and a bias spring that pushes in the opposite direction. The switch&rsquo;s contact changes state when the pressure on the switch&rsquo;s inlet side rises above the pressure exerted by the bias spring on the other side. Conversely, the switch returns to its original state once the inlet pressure falls below a predetermined threshold. Due to a phenomenon known as hysteresis, that threshold may or may not be the same as its actuation level. In some cases, hysteresis can be used to one&rsquo;s advantage when attempting to stabilize pneumatic systems.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/Automate_Table.gif" style="width: 595px; height: 479px;" /></p> <p>Pressure transducers, on the other hand, are devices with continuously varying analog or digital output (voltage, current, resistance, I<sup>2</sup>C, etc.) that&rsquo;s proportional to the pressure they see on their input. Several types of devices can translate a mechanical pressure into a detectable electrical signal, including piezorestistive transducers, whose versatility and cost makes them the most commonly used transducer.</p> <p>Piezoresistive transducers operate on the principle that certain semiconductor materials, such as silicon, change resistance with stress or strain. These piezoresistive elements are implanted on a silicon chip attached to a mechanical sensing element (such as a diaphragm) or used as the sensing element. When a bridge circuit (e.g., wire filament strain-gage transducer) incorporates piezoresistive elements, it produces an analog voltage signal that&rsquo;s proportional to the applied pressure.</p> <p>Like most transducers, piezoresistive devices don&rsquo;t react in a linear manner to pressure stimulus. They also exhibit a tendency to drift over time, or in response to environmental conditions. Traditionally, drift and nonlinearities were corrected by external means. Now, however, many modern transducers contain integrated electronics that linearize the sensing element&rsquo;s raw output and convert it into one of several standard electrical voltage or current ranges. Many of these devices also provide some degree of stabilization against temperature and time-related drift.</p> <h3> A Switch or a Transducer?</h3> <p>Some applications, especially those involving detection of an upper or lower pressure threshold, make it tough to decide whether to use a pressure switch or a pressure transducer. This is most apparent in new products or radical updates of existing designs. It&rsquo;s seemingly less of an issue for compressors, pneumatic control systems, and many other mature products and applications that already have well-defined requirements.</p> <p>In fact, it&rsquo;s probably useful to weigh your options for nearly every design project. Sometimes a new look at a mature design can yield fresh insights and unexpected improvements. The table summarizes general advantages and disadvantages of pressure switches and transducers.</p> <div class="related-content"> <div class="related-label"> Related</div> <p><a href="http://hydraulicspneumatics.com/200/FPE/Sensors/Article/False/6439/FPE-Sensors">Fundamentals of Pressure Transducers</a></p> <p><a href=" http://hydraulicspneumatics.com/other-components/spikes-put-pressure-transducers">Spikes Put Pressure On Transducers</a></p> <p><a href=" http:///hydraulicspneumatics.com/blog/visitors-bring-us-scoop-pressure-transducers">Visitors bring us a scoop on pressure transducers</a></p> <p><a href=" http://hydraulicspneumatics.com/200/TechZone/HydraulicValves/Article/False/45407/TechZone-HydraulicValves">Electrohydraulic control in plastic parts production</a></p> </div> <h2> <strong>Matching the Transducer to the Application</strong></h2> <p>When your design does indeed require a pressure transducer, selecting the right device comes down to only buying the performance and capabilities you need, and avoid paying for those you don&rsquo;t. In practice, that&rsquo;s not always as simple as it sounds, but the following list of selection considerations should help ease the process. Once you&rsquo;ve selected the criteria relevant to your application, determine the values that will meet your requirements.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/AutomateWithAir_Fig.gif" style="width: 595px; height: 592px;" title="Pressure sensors play many roles in modern compressor operation. Switches are used to ensure prompt action if pressure crosses a critical threshold. Transducers provide the information required by the control system to optimize its performance, improve its efficiency, and assure safe, reliable operation. " /></p> <h3> Selection Considerations</h3> <p>&bull; <em>Pressure range:</em> What are the anticipated maximum and minimum pressures for your application? Do you need to expand the range requirements above and below your formal requirements to cover unanticipated conditions? What are your units of measurement (psi, bar, mm Hg, etc.)?<br /> &bull; <em>Accuracy and stability:</em> How accurate does the pressure measurement need to be?<br /> What is the tolerable maximum total error band (TEB) for the application? TEB is a comprehensive, clear, and meaningful way to express the transducer&rsquo;s true accuracy over a compensated temperature range with respect to a variety of different potential error sources. Honeywell&rsquo;s PX2 series, for example, offers TEB of &plusmn;2% across a temp range of &ndash;40 to 125&deg;C (&ndash;40 to 257&deg;F).<br /> &bull; <em>Signal conditioning:</em> Should the transducer output its readings as a voltage, current, or resistance?<br /> What output range do you need from the transducer, and in what type of units?<br /> &bull;<em> Electrical and EMI protection:</em> What is maximum level of electromagnetic interference (EMI) you&rsquo;ll need your application to operate reliably in? What are the highest levels of EMI and extraneous voltage your application&rsquo;s transducers must be able to survive without damage? For example, Honeywell&rsquo;s PX2 series provides protection up to 100 V/m (ISO 11452-2 certification available).<br /> &bull; <em>Environmental conditions:</em> What&rsquo;s the required operating temperature range?<br /> What are the maximum tolerable levels of shock and vibration? Many Honeywell pressure transducers are rated for 100G (per MIL-STD-202F, Method 213B, Cond. F, and a vibration rating of 20 G sweep, 10 Hz to 2000 Hz). What ingress protection must a transducer meet to work in application conditions?<br /> &bull; <em>Media compatibility:</em> What&rsquo;s the temperature range of the media being measured? Does it have corrosive properties?<br /> &bull; <em>Packaging and mounting options:</em> The environmental, media compatibility, and mechanical issues you&rsquo;ve already considered will provide lots of guidance on the packaging requirements for a stand-alone transducer. But for some applications, it may be worthwhile to consider a board-mounted transducer that&rsquo;s co-located with the application&rsquo;s other electronics. Board-mounted pressure transducers can provide space-saving solutions with specialized port options, giving the transducer access to the gas or fluid being monitored while it resides within the electronics module&rsquo;s relatively benign environment.<br /> &bull; <em>Mechanical and electrical interfaces:</em> Does the application have any specific mounting holes, brackets, or other hard points the transducer needs to attach to? If so, what holes, flanges, or other features does the transducer housing need to have to mount where it&rsquo;s needed? What are the types of pressure input fittings and electrical connectors that are required for the transducer?<br /> &bull; <em>Additional considerations:</em> Will the operating environment pose any additional challenges (vibration, rapid temperature cycling, corrosive vapors etc.)? What type of pressure will be monitored&mdash;gauge, absolute, differential, or sealed? Does the application pose any size or cost constraints?</p> <table border="0" cellpadding="0" cellspacing="0" width="570"> <tbody> <tr> <td width="41"> <img src="http://insidepenton.com/electronic_design/adobe-pdf-logo-tiny.png" /></td> <td style="padding-left: 0px;" width="459"> <a href="/datasheet/sensing-decisions-under-pressure-pdf-download">Download this article in .PDF format</a><br /> This file type includes high resolution graphics and schematics when applicable.</td> </tr> </tbody> </table> <h3> Conclusions</h3> <p>With this basic understanding for selecting the right pressure sensor to meet design objectives, it&rsquo;s time to apply this knowledge. These principles can be applied to a more complex real-world application, say, a whole-plant air compressor used in manufacturing for operating presses, pick-and-place and other production machines, and air tools used in assembly operations. Proper placement of switches and transducers can provide a link between the plant&rsquo;s pneumatic and electronic control systems. This tie-in makes it possible to monitor production; conduct statistical process control; aid troubleshooting by identifying operating parameters that fall out of tolerance; and even conduct proactive maintenance by examining changes and trends in pressure that signal necessary actions to be taken before there&rsquo;s an occurrence of failure.</p> <p>To do this, you must have a clear understanding of your application&rsquo;s job, how it does that job, and its targeted environments. Once that&rsquo;s done, following the questions and suggestions offered in this article will help narrow your search to the handful of choices that offer the best mix of performance, reliability, and total cost of ownership.</p> <p><em>Ketan Mehta is Senior Product Marketing Manager at <strong><a href="http://sensing.honeywell.com" target="_blank">Honeywell&rsquo;s Sensing &amp; Control Group</a></strong>, Minneapolis. </em></p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/controls-instrumentation/sensing-decisions-under-pressure#comments Controls & Instrumentation Thu, 13 Nov 2014 15:45:00 +0000 29721 at http://hydraulicspneumatics.com Tried & True Ways of Dealing with Air in Hydraulic Fluid http://hydraulicspneumatics.com/blog/tried-true-ways-dealing-air-hydraulic-fluid <div class="node-body blog-body"><p>In collecting information for my next series of blogs, I ran across another article from long ago that piqued my interest, and I think readers can learn a lot from it. It describes how air getting into the hydraulic circuit for steering an F-104 fighter aircraft caused erratic operation. More importantly, it explains what was done to correct the problem.</p> <p>Once again, this article deomonstrates that even though hydraulics has made huge advancements in the last 50 years, we can still learn a lot from some of these classic articles from the archives of <em><strong>Hydraulics &amp; Pneumatics</strong></em>. By the way, I also placed references to other classic aritcles dealing with aeration of hydraulic fluids in the Related Article box after the end of this article.<br /> &nbsp;</p> <h3> Separator de-aerates oil, stops shimmy on F-104 nose wheel</h3> <p><em>Two Lockheed engineers developed a new type of air extractor to overcome a problem that had bugged the steering-damping unit on the F-104 aircraft for years.</em></p> <p>By Robert M. Livesey and Mark H. Ettinger</p> <p>Symptoms typical of an aerated hydraulic system plagued the F-104 aircraft for many years. (To understand what fluid aeration is and how fluids become aerated, see the box, &ldquo;How fluids become aerated.&rdquo;) Aeration was caused by system components with built-in chambers and passages where free air (bubbles) collected when system fluid was saturated or at rest with no pressure acting on the fluid.</p> <p><a href="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/Lockheed XF-104.jpg"><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/Lockheed%20XF-104.jpg" style="width: 400px; height: 142px; float: right; margin-left: 4px; margin-right: 4px;" title="Lockheed's F-104. Click on image for larger view. Photo courtesy of the United States Air Force." /></a>The steering-damping unit of the nose landing gear on the F-104 aircraft is a typical hydraulic component. It extracts energy from hydraulic fluid by restricting flow between two chambers and, thus, damps nose wheel oscillation. If the fluid is aerated, the energy extracted diminishes until it reaches a level where the damping energy is below the unbalancing force of the wheel, and shimmy sets in.</p> <p>Several types of air extraction devices then available were tested over a span of years. Unfortunately, they were not effective in the pressure environment of the aircraft system. Finally, basic studies were undertaken. Theories were explored, which led to the construction and testing of a laboratory model of an air-oil separator that stopped the nose-wheel shimmy.</p> <p><strong><a href="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/1967.10-F104 Fig 1.jpg"><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/1967.10-F104%20Fig%201.jpg" style="width: 333px; height: 295px; float: left; margin-left: 4px; margin-right: 4px;" title="Air-oil separator installation on the Lockheed F-104 aircraft. Each of the aircraft's two hydraulic systems has a separator. Click on image for larger view." /></a>Theory of Operation</strong></p> <p>This air-oil separator operates on the principle of lowering the pressure (to a desired vacuum) in a chamber containing small quantities of hydraulic fluid continually bypassed from a pressurized dynamic system. The gases thus released from the fluid are collected and prevented from being returned to the system. The gases are stored for removal at convenient intervals when the hydraulic system is at rest.</p> <p><strong>Wire Mesh Screen Separates Bubbles</strong></p> <p>Initial attempts at actually constructing the air-oil separator involved using a 10-micron (nominal) wire mesh filter screen as a barrier because of its ability to resist the passage of air. This resistance is demonstrated by the familiar bubble test used on filter elements wherein the element does not pass an air bubble until the pressure differential is at least 9 inches of water. This premise was correct in that air did not pass through a 10-micron filter screen as long as the air was in the form of small bubbles. In other words, free air did not pass through the filter screen when the air content of the fluid was well above the saturation point.</p> <p><strong>Aspirator Vacuums Air From Fluid</strong></p> <p><a href="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/1967.10-F104 Fig 2.jpg"><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/1967.10-F104%20Fig%202.jpg" style="width: 333px; height: 333px; float: right; margin-left: 4px; margin-right: 4px;" title="High-pressure hydraulic fluid passing through the air-oil separator removes air from low-pressure fluid bypassed from the return line. Click on image for larger view. " /></a>Unfortunately, bubbles get smaller with increasing pressure. The lowest pressure in the F-104 is about 30 psig. This pressure was far too high because even at this pressure the free air bubbles would be compressed and driven through the filter screen. Total bubble removal was not possible. The next logical step was to introduce an aspirator, which would reduce the pressure in the chamber so the bubbles would expand and not penetrate the filter screen.</p> <p>It was at this stage that the scheme to use a jet pump (aspirator) to lower the pressure in the separating chamber was tried. By lowering the pressure acting on the fluid, large quantities of dissolved and free air were released and the filter screen barrier was able to separate the bubbles from the fluid.</p> <p><strong>Air </strong><strong>Re-absorbed </strong><strong>Quickly</strong></p> <p><a href="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/1967.10-F104 Fig 3.jpg"><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/1967.10-F104%20Fig%203.jpg" style="width: 250px; height: 320px; float: left; margin-left: 4px; margin-right: 4px;" title="Lockheed air-oil separator. Hydraulic fluid at system (high) pressure passing through the separator creates a low-pressure region in the separator. This low pressure allows air bubbles to form in the aerated fluid and also aspirates the fluid. The bubbles are screened out by the separator (10-micron, wire mesh filter) element, and the air is temporarily stored in the air storage chamber. This air-oil separator· with a separator or filter element has been qualified for the F-104. However, other versions of the air-oil separator have the aspirator at the bottom of the unit instead of the top, avoiding the need for a filter element. Click on image for larger view." /></a>During the development testing it was noted that fluid released of its air by the separator would quickly reabsorb air when left in an exposed container. The de-aerated fluid acted somewhat like a sponge. This phenomenon was proved very beneficial in bleeding complex systems such as that of the F-104. The most remote reaches of the system are bled effectively by circulating treated (de-aerated) fluid throughout the system, reabsorbing pockets of air. Nooks and crannies that would normally never get bled using conventional bleeding methods are easily cleared of air.</p> <p>On F-104 aircraft, two separators &mdash; one for each hydraulic system &mdash; are in operation whenever the aircraft hydraulic system is used, either in flight or on ground test stand power. Extracted air is easily bled-off during ground servicing with a conveniently located pushbutton-operated bleed valve in each system that sequentially blocks jet pump flow and opens the air storage chamber to the atmosphere.</p> <p><strong>Sizing Separator to System</strong></p> <p>An air-oil separator can be designed to fit most&nbsp; hydraulic system requirements by varying the volume of pressurized flow, separating chamber and filter size, and servicing frequency.</p> <p><a href="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/1967.10-F104 Fig 4.jpg"><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/1967.10-F104%20Fig%204.jpg" style="width: 250px; height: 281px; float: right; margin-left: 4px; margin-right: 4px;" title="Graph shows the great solubility of air in MIL-H-5606 hydraulic fluid. At 14.7 psia, 5606 hydraulic fluid could dissolve air up to 11% of fluid volume. Click on image for larger view." /></a>The volume of separating flow and separating chamber vacuum pressure can be balanced by adjusting the size of the inlet restrictor. The jet pump should be sized according to the amount of pressurized flow that can be spared from the system and the amount of heat that the system can tolerate. (Pressure drop across the pump nozzle adds heat to the fluid.)</p> <p>If an air-oil separator is considered during the early stages of system design, the separating filter can be integrated with system filtration requirements since the separator is ideally situated in a bypass loop of the system with relatively low flow rates and low return pressure.</p> <p><em>Robert Livesey is a senior design specialist, Advanced Development Division, and Mark Ettinger is a senior design engineer, F-104 Project, Locklweed-California Co., Burbank, Calif. They are the inventors of this air-oil separator, which was developed in 1962 for the F-104.</em></p> <p><em>Lockheed-California Co., has licensed exclusively the Seaton Wilson Mfg. Co., Burbank, Calif., to develop, manufacture, and sell these air-oil separators that use a jet pump to aspirate gases from liquids.</em></p> <p>&nbsp;</p> <h3> <strong>How Fluids Become Aerated</strong></h3> <p>Air can enter a hydraulic system in many ways, and, according to Henry&#39;s Law, will be dissolved in a fluid in proportion to the pressure acting on the fluid. Thus, considerable quantities of air can be dissolved in a system that has a pressurized reservoir because the pressurizing media (air or a gas) is in direct contact with the fluid surface. Additional quantities of air may be introduced by aircraft servicing equipment, such as hydraulic ground test stands, which also use air-pressurized reservoirs.</p> <p>When the system is at rest and unpressurized, air in excess of that which can naturally be dis solved at the zero pressure condition is released as free air.</p> <p><strong>Effects of Air</strong><br /> Air in a hydraulic system has many detrimental effects on both component and system performance. The more obvious symptoms of an aerated system are system oscillation, power loss, cavitation, increased fluid heat, response lag, foaming, and &quot;spongy&quot; controls. Loss of power and a &quot;soft&quot; system can be directly attributed to a decrease in the bulk modulus (greater compressibility) of the fluid because of an increasing air content.</p> <p style="margin-left:45.0pt;"><strong>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Editorial Advisory Board</strong></p> <p style="margin-left:45.0pt;">Charles H. Cannon&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Howard D. Davis<br /> Lockheed-Georgia Co.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; General Dynamcis/Convair</p> <p style="margin-left:45.0pt;">Kenneth W. Dubois&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Grady Gilder, Jr.<br /> Douglas Aircraft Co.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; LTV Aeronautics Div.</p> <p style="margin-left:45.0pt;">John W. Ruttle, Jr.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Frank M. Ladnich<br /> The Martin Co..&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Grumman Aircraft Engineering Corp.</p> <p style="margin-left:45.0pt;">E. T. Raymond&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; William W. Mayhew<br /> The Boeing Co.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Grumman Aircraft Engineering Corp.</p> <p><em>This article was originally published in the January 1967 issue of <strong>Hydraulics &amp; Pneumatics</strong>.</em></p> </div> <div class="og_rss_groups"><ul class="links"><li class="og_links first last"><a href="/blog/hitch-post">The Hitch Post</a></li> </ul></div> http://hydraulicspneumatics.com/blog/tried-true-ways-dealing-air-hydraulic-fluid#comments Aerospace Hydraulic Fluids Hydraulic Pumps & Motors The Hitch Post Thu, 13 Nov 2014 11:24:00 +0000 29531 at http://hydraulicspneumatics.com November 2014 http://hydraulicspneumatics.com/hydraulics-pneumatics/2014-11-13 <div class="node-body magazine_issue-body"></div> <fieldset class="fieldgroup group-mag-teasers"> <div class="field-mag-teaser"> <a href="/marine-offshore/deep-seas-push-hydraulic-system-boundaries">Deep Seas Push Hydraulic-System Boundaries</a> <a href="/marine-offshore/workboat-show-chugs-nola">WorkBoat Show Chugs into NOLA</a> <a href="/hydraulic-pumps-motors/pump-controls-optimize-hpu-performance">Pump Controls Optimize HPU Performance</a> </div> </fieldset> <fieldset class="fieldgroup group-publication-info"><legend>Publication Info</legend> </fieldset> <div class="og_rss_groups"></div> Thu, 13 Nov 2014 05:00:00 +0000 29791 at http://hydraulicspneumatics.com WorkBoat Show Chugs into NOLA http://hydraulicspneumatics.com/marine-offshore/workboat-show-chugs-nola <div class="field-byline"> Alexis Coffey </div> <div class="field-deck"> Expect this year’s annual show and conference to highlight the best of the marine industry. </div> <div class="node-body article-body"><p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/450451431.jpg" style="width: 333px; height: 220px; float: left; margin-left: 4px; margin-right: 4px;" /></p> <p>One of the final shows of 2014, <a href="http://www.workboatshow.com" target="_blank">The International WorkBoat Show and Annual Conference</a>, takes place December 3rd through 5th at the Morial Convention Center in New Orleans. This year&rsquo;s show is expected to have more than 1,000 marine product and service suppliers in attendance. At the show, attendees have the opportunity to meet and troubleshoot with industry experts, negotiate with product suppliers, and discuss the latest marine technological advances.</p> <p>The annual conference spans across all three days. Conference presentations include topics on vessel construction and repair; technical, business management, and legal regulations; and safety, security, and training.&nbsp; Each day has multiple sessions coinciding with one another, allowing attendees to choose topics that best suit their particular needs.</p> <p>Three keynote speakers will present at the conference: Frank Foti, President and CEO of Vigor Industrial; Paul N. Jaenichen, Sr. Maritime Administrator, U.S. Department of Transportation, Maritime Administration; and Capt. Richard Phillips. The keynote presentations will begin with Captain Phillips, the notable seaman who was famously taken hostage in 2009 after Somali pirates hijacked his ship.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/matthew_cg_hr%5B1%5D.jpg" style="width: 400px; height: 314px; float: right; margin-left: 4px; margin-right: 4px;" title="Boats at work: A 25-foot U.S. Coast Guard boat provides a security escort for a liquefied natural gas tanker in Boston Harbor. Photo credit: U.S. Coast Guard photo by Public Affairs Specialist 3rd Class Kelly Newlin." />At the end of the second day, also referred to as &ldquo;Shipyard Day,&rdquo; there will be a special awards ceremony hosted by the editors of <em>WorkBoat</em> magazine. Every year, the editors review boats showcased by the magazine throughout the year and then choose 10 significant boats for special recognition. The boats are chosen for speed, design, technology, and more. This is the first year the boats will be announced in advance, and one of the boats will ultimately be selected as the 2014 Boat of the Year.</p> <h3> Workboat Maintenance and Repair</h3> <p>Look forward to more from WorkBoat next year at the inaugural <a href="http://www.workboatmaintenanceandrepair.com" target="_blank">WorkBoat Maintenance and Repair Conference and Expo</a>, which will also be held at the Morial Convention Center in New Orleans, April 14-16, 2015. This conference and expo will focus on issues and solutions surrounding maintenance and repair in the workboat industry. The event will feature a seminar and keynote program for up to 2,000 maintenance and repair professionals. As many as 150 exhibitors are expected to display products, services, and other solutions related to workboat maintenance and repair.</p> <h3> <strong>FLUID-POWER-RELATED EXHIBITORS</strong></h3> <p><strong><a href="http://www.workboatshow.com/images/pdf/2014floorplan.pdf" target="_blank">Click here</a></strong> to download a PDF of the floor plan.<br /> <strong><a href="http://www.workboatshow.com/images/pdf/exhiblist_alpha.pdf" target="_blank">Click here</a></strong> to download a PDF of the full exhibitor list in alphabetical order, or <strong><a href="http://www.workboatshow.com/images/pdf/exhiblist_booth.pdf" target="_blank">click here</a></strong> to download a PDF in booth number order.<br /> <strong>Company name</strong>&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <strong>Booth number</strong><br /> A/M Air Starters.............................2111<br /> Air Starter Components Inc............2551<br /> Altra Industrial Motion.....................362<br /> Atlas Copco Compressors LLC........836<br /> Aventics Corp..,............................3715<br /> Baldor Electric Co.........................1050<br /> Baldwin Filters..............................3571<br /> Bauer Compressor........................3907<br /> Behringer.....................................2542<br /> Bosch Rexroth Corp.....................2202<br /> Centa Corp..................................3520<br /> Chevron Lubricants.....................3328<br /> CITGO Petroleum Inc...................1552<br /> Coxreels Inc................................3465<br /> Dixon Valve.................................2457<br /> Donaldson Co. Inc.......................1161<br /> Durst...........................................2952<br /> ExxonMobil.................................3020<br /> Force Control Industries Inc...........751<br /> Hannay Reels...............................4044<br /> The Hilliard Corp.........................1561<br /> Hydraquip Custom Systems Inc....2542<br /> K &amp; L Clutch &amp; Transmission Inc....343<br /> Kluber Lubrication NA LP.............1463<br /> <a href="http://www.kocsistech.com/" target="_blank"><strong>Kocsis Technologies Inc..............1856</strong></a><br /> Logan Clutch Corp......................3802<br /> Orttech.......................................3460<br /> Panolin America Inc....................2558<br /> Royal Purple Inc..........................2151<br /> RSC Bio Solutions........................4066<br /> Schroeder Industries...................2542<br /> Tranter Inc..................................2528<br /> Twin Disc Inc..............................3102<br /> Voith Turbo Inc...........................2836<br /> WAGO Corp..................................806<br /> <strong><a href="http://www.wandfluh-us.com/" target="_blank">Wandfluh of America</a>....................2542</strong><br /> Wilkes &amp; McLean Ltd..................3353<br /> Wooster Hydrostatics Inc.............759<br /> WPT Power Corp.........................3915</p> <table border="0" cellpadding="0" cellspacing="0" width="570"> <tbody> <tr> <td width="41"> <img src="http://insidepenton.com/electronic_design/adobe-pdf-logo-tiny.png" /></td> <td style="padding-left: 0px;" width="459"> <a href="http://http://hydraulicspneumatics.com/datasheet/workboat-show-chugs-nola-pdf-download">Download this article as PDF file</a><br /> This file type includes high resolution graphics and schematics when applicable.</td> </tr> </tbody> </table> <p>&nbsp;</p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/marine-offshore/workboat-show-chugs-nola#comments Marine & Offshore Hydraulic Fluids Wed, 12 Nov 2014 21:34:00 +0000 29701 at http://hydraulicspneumatics.com Pneumatics, with a side of fries http://hydraulicspneumatics.com/food-beverage/pneumatics-side-fries <div class="node-body article-body"><p>Before the age of computer networks and PCs, pneumatic-tube conveying systems were widely used in offices, factories, and other large establishments to transport paperwork and small objects from one area of a building to another in just a few seconds. These useful systems are still widely used in niche applications today, such as bank drive-in stations and hospitals &mdash; where their ability to transport small physical objects is not possible with even the fastest and most powerful computers. In most commercial applications, though, they have been rendered obsolete by email and other forms of digital communication. However, a new niche for the tubes may have recently emerged within the food industry.</p> <table border="0" cellpadding="0" cellspacing="0" width="570"> <tbody> <tr> <td width="41"> <img src="http://insidepenton.com/electronic_design/adobe-pdf-logo-tiny.png" /></td> <td style="padding-left: 0px;" width="459"> <a href="http://hydraulicspneumatics.com/datasheet/pneumatics-side-fries-pdf-download">Download this article in .PDF format</a><br /> This file type includes high resolution graphics and schematics when applicable.</td> </tr> </tbody> </table> <p>In an effort to change up the average dining experience, a New Zealand restaurant installed a pneumatic tube conveying system to add an effective and creative twist to customers&rsquo; food delivery experience. Inspired after watching a cartoon that used tubes to deliver food, <a href="http://www.c1espresso.co.nz" target="_blank">C1 Caf&eacute;</a> owner Sam Crofskey decided to turn the idea into reality by incorporating the tubes in the rebuild of his restaurant. The installation of the new food delivery system was just one way to make his cafe stand out from others.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/News-lead.jpg" style="width: 595px; height: 409px;" title="The C1 Café has a special menu containing all items that can be delivered via pneumatics. This salmon burger combo was in the kitchen just seconds before being delivered to the customer’s table. " /></p> <p>Pneumatic conveying systems are extremely reliable because they have few moving parts. Power for the system is usually provided by a centrifugal blower, which pulls a partial vacuum to draw the capsule into the tubing network. The blower also produces positive pressure at its discharge that can be used to push tubes through the tubing. The user places paperwork or a small object inside a capsule, opens a door to the pneumatic transporter, and places the capsule inside. Once the door is closed, the capsule then speeds on its way to the destination.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/Inset-photo.jpg" style="width: 595px; height: 283px;" title="Shown is a loading station and a portion of the tubing." /></p> <p>At first, the tubes were used by wait staff to send orders back to the kitchen as a trial to see if this could work. Following that success, the next step was to install heavy-duty tubing to handle the weight of burgers. C1 Caf&eacute;&rsquo;s customers choose from a &ldquo;Pneumatic Menu,&rdquo; which includes the signature dish, three sliders, and an option of fries. A kitchen worker places the order into a stainless-steel capsule, loads it into the appropriate tube, and the order is sent flying through the tube system at 87 mph to a station near the diner&rsquo;s table. To prevent any damage to the food, a custom air-brake system slows the canister down before delivery.</p> <p>Installation of the tubes has been a lengthy process, taking around a year to complete. Crofskey hopes to eventually relocate tubes under the floor and up through the table legs to avoid the space being cluttered up with tubes and also deliver orders right to the customers&rsquo; table, bringing a whole new meaning to the term &ldquo;fast food.&rdquo;</p> <p>Check out <a href="http://www.c1espresso.co.nz" target="_blank">C1 Caf&eacute;</a>, or <a href="http://bit.ly/HP1411NewsC1" target="_blank">see the system in action</a>. The CI Caf&eacute; even shows a journey through the tubing via a small video camera on a capsule.</p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/food-beverage/pneumatics-side-fries#comments Food & Beverage Hose & Tubing Wed, 12 Nov 2014 20:42:00 +0000 29671 at http://hydraulicspneumatics.com Hydraulic-Electric Analogies: Capacitors and Accumulators, Part 1 http://hydraulicspneumatics.com/accumulators/hydraulic-electric-analogies-capacitors-and-accumulators-part-1 <div class="field-deck"> Developing an understanding of hydraulic capacitance helps eliminate pesky parasitic capacitances, and facilitates the overall application of circuit theorems in hydraulic design. </div> <div class="node-body article-body"><p><em>This article is the latest in Jack Johnson&#39;s series on Hydaulic-Electric Analogies. See the &quot;Related&quot; articles list below for previous articles in the series.</em></p> <table border="0" cellpadding="0" cellspacing="0" width="570"> <tbody> <tr> <td width="41"> <img src="http://insidepenton.com/electronic_design/adobe-pdf-logo-tiny.png" /></td> <td style="padding-left: 0px;" width="459"> <a href="/datasheet/hydraulic-electric-analogies-capacitors-and-accumulators-part-1-pdf-download">Download this article in .PDF format</a><br /> This file type includes high resolution graphics and schematics when applicable.</td> </tr> </tbody> </table> <p>Electrostatic fields are relatively unimportant in the hydraulic world, but they have great significance in the electrical and electronic media. From an electrohydraulic point of view, the most important use for the electrostatic field is in the electrical capacitor. Analogously, the electrical capacitor is significant in that it gives rise to the hydraulic capacitor.</p> <p>Not surprisingly, electrical capacitors are rated in terms of their capacitance. Capacitors can be either polarized or non-polarized <em>(Fig. 15)</em>. Polarized types require that applied voltage polarity be strictly observed, while non-polarized caps don&rsquo;t have that constraint.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/28.gif" style="width: 595px; height: 278px;" title="Fig. 15. Capacitors can be polarized or non-polarized, and are distinguished by their schematic symbols. The polarity of applied voltage must be strictly observed with polarized capacitors or they can be damaged by reverse voltage." /></p> <p>The working units for capacitance are ampere-second/volt, otherwise referred to as <em>farad</em>. The popular workaday unit for capacitance is the microfarad, a millionth of a farad, normally abbreviated as &micro;F. Again, as in the case of inductors, time enters into the units and interpretation. Hydraulic capacitance in conventional US units would be (in.<sup>3</sup>/sec) sec/psi, which can be simplified to in.<sup>3</sup>/psi. That can be further simplified to in.<sup>5</sup>/lb when measuring flow in the very convenient in.<sup>3</sup>/sec and pressure in psi.</p> <p>Hydraulic capacitance has no established workaday unit. However, I unabashedly refer to the hydraulic farad and hydraulic microfarad, and abbreviate them as <em>hyfd</em> and the <em>&micro;hyfd</em>, respectively. In the metric world, the working units for hydraulic capacitance are the unwieldy lpm &times; sec/bar when pressure is in bar and flow is in liters per minute. As of this point, no known movement has emerged to standardize this anomalous construct.</p> <p>An electrical capacitance exists any time two conductors are separated by a dielectric. For the moment, a dielectric material is an insulator; that is, some material that does not conduct electrical current. There are two kinds of electrical capacitance: deliberate (which is not an accepted technical term) and unintentional, better known as parasitic capacitance.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/29.gif" style="width: 595px; height: 334px;" title="Fig. 16. A simple capacitor can consist of two parallel plates separated by an insulating material, such as air or another dielectric material." /></p> <p>The deliberate capacitor, a device that&rsquo;s been built, sold, and applied for its special electrical properties, is deliberately wired into the receiving circuit <em>(Fig. 16)</em>. Capacitance is directly proportional to the area of the plates (<em>Z</em>&times;<em>Y</em> from the figure) and inversely proportional to the plate separation, <em>x</em>:</p> <p><em>C</em> = <em>&epsilon;</em> &times; <em>A/x</em></p> <p>where <em>C</em> is capacitance; <em>&epsilon;</em> is the permittivity of the material (a property of the dielectric separator); <em>A</em> is the area of one of the plates in the simple parallel plate construction; and <em>x</em> is the plate separation distance.</p> <p>Free space has a permittivity of 8.85 &times; 10<sup>-12</sup> farad/m. Some glass has a permittivity that&rsquo;s 10 times higher, and strontium titanate is 200 times greater. Capacitor designers take advantage of the permittivity values to get higher and higher amounts of capacitance in ever-decreasing package sizes.</p> <p>The parasitic capacitance doesn&rsquo;t arise through deliberate human processes, but rather because the circuit is built using conductors. And all conductors are separated from other conductors by insulators, preventing the potentially tragic consequences of having the currents in one conductor leak into the conductors of other circuits.</p> <div class="related-content"> <div class="related-label"> Related</div> <p><a href="http://hydraulicspneumatics.com/other-technologies/hydraulic-electric-analogies-part-7-variable-electrical-transformers">Hydraulic-Electric Analogies &mdash; Part 7: Variable Electrical Transformers</a></p> <p><a href="http://hydraulicspneumatics.com/other-components/hydraulic-electric-analogies-part-6-coils-cores-and-transformers">Hydraulic-Electric Analogies &mdash; Part 6: Coils, Cores, and Transformers</a></p> <p><a href="http://hydraulicspneumatics.com/other-technologies/hydraulic-electric-analogies-part-5-current-and-electrical-fields">Hydraulic-Electric Analogies, Part 5: Current and Electrical Fields</a></p> <p><a href="http://hydraulicspneumatics.com/other-technologies/hydraulic-electric-analogies-part-4-comparing-power-sources">Hydraulic-Electric Analogies, Part 4: Comparing Power Sources</a></p> <p><a href="http://hydraulicspneumatics.com/controls-instrumentation/hydraulic-electric-analogies-part-3-open-and-closed-contradiction">Hydraulic-Electric Analogies, Part 3: The Open and Closed Contradiction</a></p> <p><a href="http://hydraulicspneumatics.com/other-technologies/hydraulic-electric-analogies-part-2-voltage-and-pressure">Hydraulic-Electric Analogies, Part 2: Voltage and Pressure</a></p> <p><a href="http://hydraulicspneumatics.com/technologies/hydraulic-electric-analogies-part-1">Hydraulic-Electric Analogies, Part 1</a></p> </div> <p>In other words, if you build a circuit, it will have parasitic capacitances. The aim is to keep their values low enough so that the capacitive properties don&rsquo;t appreciably affect the circuit&rsquo;s performance. Fortunately, the affects of parasitic capacitance in, for example, a typical servo amplifier, or proportional valve amplifier, are negligibly small.</p> <p><strong>The Deliberate Electrical Capacitor</strong></p> <p>Capacitance increases by expanding the area of the conductor. Two parallel plates will exhibit measurable capacitance, which can be enhanced by placing the plates closer together. In the construction of the capacitor, the plates are separated by a thin insulating material measuring only a few thousandths of an inch thick. <em>Figure 17</em> shows how the two conductors are rolled up in a spiral manner to stuff the two-layer assembly into a small cylindrical can. The two conducting layers are separated by two respective layers of the insulating materials (not shown in the figure). This construction method produces the greatest possible capacitance in the smallest possible volume.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/30.gif" style="width: 595px; height: 320px;" title="Fig. 17. To maximize capacitance while minimizing package size, the two conductors are separated by insulating material (not shown) and rolled up in spiral fashion to fit into a cylindrical package." /></p> <p>Before exploring deeper into how the electrical capacitor works, let&rsquo;s first discuss the hydraulic capacitor to gain physical insight. The key factor here is that the electrical capacitor stores charges (electrons and those other fictitious positive things), while the hydraulic capacitor &mdash; the accumulator &mdash; stores molecules of hydraulic fluid.</p> <p><strong>The Deliberate Hydraulic Capacitor</strong></p> <p>Similar to the electric capacitor, capacitance in the hydraulic circuit is both deliberate and parasitic. The deliberate hydraulic capacitor, called an accumulator, can be constructed in any one of several ways. The most common construction is gas-over-liquid, which incorporates either a bladder or piston <em>(left and right, respectively, Fig. 18)</em> to separate the compressible gas chamber from the liquid chamber.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/31.gif" style="width: 595px; height: 420px;" title="Fig. 18. Most hydraulic accumulators store pressurized liquid by virtue of compressing a gas in a separated chamber. The separator is either a bladder or a piston." /></p> <p>It&rsquo;s generally accepted that the two accumulators have essentially identical characteristics; however, research is needed in terms of comparing their performance. Like so many mechanical and hydromechanical machines, having some knowledge of their construction aids in understanding their function. The two accumulator types in Figure 18 offer a good starting point.</p> <p>In the accumulator symbol <em>(Fig. 19)</em>, there&rsquo;s only the essential parts&mdash;the hydraulic inlet/outlet port, the liquid side, the gas side, and the separator. The open triangle on the gas side conveys that it&rsquo;s precharged with a gas, but doesn&rsquo;t indicate the type of gas nor the amount of precharge on the gas side. The symbol also doesn&rsquo;t reveal the construction type. The colors are non-standard.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/32.gif" style="width: 595px; height: 356px;" title="Fig. 19. The accumulator symbol has the essentials of a real accumulator." /></p> <p>Regardless of the construction type, the practical hydraulic capacitor has a gas side and a liquid side. The liquid side (hydraulic side) is typically connected to the active hydraulic circuit in its application. The gas side is usually &ldquo;pumped up&rdquo; to some precharge pressure with an inert gas, such as argon or nitrogen. The precharge pressure is in the same range as the operational pressure in the hydraulic system, which is in the hundreds or thousands of psi. Inert gases are used to avoid the possible combustion of hydraulic fluids that may inadvertently come into contact with the pressurized gas. Oxygen-containing precharge gases could support the combustion.</p> <p>Proper and normal operation of the accumulator requires isolation of the liquid and gas sides from each other. When the accumulator is &ldquo;sitting on the shelf&rdquo; with some gas precharge pressure, the hydraulic port will be at atmospheric conditions. As a result, the precharged gas forces the bladder to completely fill the interior of the accumulator. In so doing, the bladder will contact the anti-extrusion poppet, which closes the poppet and prevents the bladder from extruding out of the hydraulic inlet/outlet port. Likewise, the gas will force the piston of the second type into its bottom position and fill the gas side.</p> <p><strong>How it Works</strong></p> <p>When connecting the accumulator into a functioning hydraulic system, realize that the accumulator will not be active until the hydraulic pressure reaches and exceeds the gas precharge pressure. After exceeding the precharge pressure on the hydraulic side, hydraulic fluid can enter and exit its side of the inlet/outlet port. As the liquid enters and exits through the hydraulic port, the gas is alternately compressed and decompressed.</p> <p>In addition, energy is stored in the compressed gas. This energy storage capability allows the accumulator to quickly release energy and liquid volume in the event that the hydraulic circuit has a sudden demand for flow. In fact, this is one of the most important functions of accumulators.</p> <p>The performance of a gas-over-oil accumulator is governed by gas laws. However, gas laws are limited in two instances: <em>adiabatic</em> and <em>isothermal</em> operation. In adiabatic operation, no thermal energy caused by the gas compression leaves the system. In isothermal operation, all energy of gas compression leaves the system so that the gas operates at a fixed temperature.</p> <p>Between the two modes, adiabatic operation is the most likely to appear in hydraulic systems. This requires that one, or both, of the following events take place. First, the cycling of the system pressure and the concomitant instantaneous gas temperature changes occur so quickly that thermal energy has no chance to leave the interior of the accumulator. Or, the accumulator must be effectively insulated to impede heat transfer.</p> <p>Accumulators usually aren&rsquo;t insulated. However, because most industrial processes cycle quickly enough, it&rsquo;s reasonable to assume that they&rsquo;re in adiabatic mode. Isothermal operation is interesting, but it won&rsquo;t likely be found in hydraulic systems due to the time required to transfer heat energy through the accumulator&rsquo;s walls to keep gas at some fixed temperature.</p> <p><strong>Formulas for Gas-Charged Accumulators</strong></p> <p><em>Figure 20</em> shows an approximate graph of a hydraulic accumulator&rsquo;s adiabatic operation. <em>V<sub>O</sub></em> represents the hydraulic volume of liquid (usually oil) that enters the hydraulic port of the gas-filled accumulator. <em>P<sub>PC</sub></em> is the gas precharge pressure value. Note that no volume enters the liquid side until the hydraulic pressure <em>(P<sub>S</sub>)</em> reaches and exceeds <em>P<sub>PC</sub></em>.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/33.gif" style="width: 595px; height: 255px;" title="Fig. 20. This chart shows adiabatic pressure-volume characteristics of a gas-over-liquid accumulator, indicating the physical volume of the accumulator and the pre-charge pressure on the gas side." /></p> <p>Further increases in hydraulic pressure result in greater amounts of hydraulic fluid entering the accumulator. When the hydraulic pressure decreases, hydraulic fluid leaves the accumulator. In other words, fluid will flow through the hydraulic throat only when the hydraulic pressure is changing and when it exceeds the gas precharge pressure. When pressure is constant, there&rsquo;s no hydraulic flow going into or out of the accumulator.</p> <p>Starting with the ideal gas laws, the volume of oil resulting from the hydraulic inlet pressure is:</p> <p><em>V<sub>O</sub></em> = <em>V<sub>ACC</sub></em> [1 &ndash; (<em>P<sub>PC</sub></em>/<em>P<sub>S</sub></em>)<sup>1/n</sup>]</p> <p>where <em>V<sub>O</sub></em> is the volume of fluid ingested into the accumulator to raise the pressure from <em>P<sub>PC</sub></em> to <em>P<sub>S</sub></em>; <em>V<sub>ACC</sub></em> is the actual physical volume of the accumulator; <em>P<sub>PC</sub></em> is the <em>absolute</em> precharge pressure of the accumulator; <em>P<sub>S</sub></em> is the <em>absolute</em> inlet hydraulic pressure; and <em>n</em> is the dimensionless universal gas constant that depends on the precharge gas. For example, nitrogen&rsquo;s&nbsp; constant is generally accepted as 1.4, whereas argon is about 1.67.</p> <p>It&rsquo;s important to use absolute pressures in the equation, so just add about 15 psi (1 bar) to the gauge pressure values when doing the calculations. The assumption of an ideal gas is reasonable at pressures encountered in most hydraulic systems.</p> <p>Hydraulic capacitance is the slope of volume-pressure curve under a given operating condition. The adiabatic capacitance for the precharged accumulator is:</p> <p><em>C<sub>H</sub></em> = (<em>P<sub>PC</sub></em><sup>1/N</sup> &times; <em>V<sub>ACC</sub></em>) / (<em>n</em> &times; <em>P<sub>S</sub></em><sup>[<em>n</em>-1]/<em>n</em></sup>)</p> <p>where C<sub>H</sub> is the hydraulic capacitance (measured as in.<sup>5</sup>/lb in IPS units). Other terms in this equation were defined earlier in the article.</p> <table border="0" cellpadding="0" cellspacing="0" width="570"> <tbody> <tr> <td width="41"> <img src="http://insidepenton.com/electronic_design/adobe-pdf-logo-tiny.png" /></td> <td style="padding-left: 0px;" width="459"> <a href="/datasheet/hydraulic-electric-analogies-capacitors-and-accumulators-part-1-pdf-download">Download this article in .PDF format</a><br /> This file type includes high resolution graphics and schematics when applicable.</td> </tr> </tbody> </table> <p>Three distinct advantages emerge when using a parameter like hydraulic capacitance. First, it allows the comparison of the deliberate capacitance to the parasitic values, enabling the elimination of parasitic capacitances when they&rsquo;re obscurely small. Second, all of the circuit theorems developed and used by electrical engineers through the decades thus becomes easy to apply to hydraulic circuits. Third, using familiar elements and equations means that electrical engineers are more likely to become interested in hydraulic-circuit analysis if their starting point has familiar terms and concepts.</p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/accumulators/hydraulic-electric-analogies-capacitors-and-accumulators-part-1#comments Accumulators Other Technologies Other Components Wed, 12 Nov 2014 19:26:00 +0000 29651 at http://hydraulicspneumatics.com Accumulator designed for deep-water applications http://hydraulicspneumatics.com/accumulators/accumulator-designed-deep-water-applications <div class="node-body article-body"><p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/Kocsis_Lockbox.jpg" style="width: 595px; height: 351px;" /></p> <p>Lockbox piston accumulator design addresses issues of costly, time-consuming, and complicated offshore accumulator service. Traditional piston accumulators have a threaded retaining ring that holds the endcap into housing. Corrosion of the large thread fuses the ring and housing together, complicating disassembly and reassembly. The Lockbox design removes the issue of corroded large threads, allowing for simpler service of accumulators right on the rig. They can be disassembled, inspected, have seals replaced.&nbsp; Reassembly is quick using standard tools.</p> <p><em><a href="http://www.kocsistech.com" target="_blank">Kocsis Technologies Inc.</a>, (708) 597-4177</em></p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/accumulators/accumulator-designed-deep-water-applications#comments Accumulators Tue, 11 Nov 2014 22:47:00 +0000 29631 at http://hydraulicspneumatics.com Fluid condition monitors http://hydraulicspneumatics.com/controls-instrumentation/fluid-condition-monitors <div class="node-body article-body"><p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/MP-Fitri-AZ23.jpg" style="width: 300px; height: 438px; float: left;" />AZ 2 ATEX fluid condition monitors feature eight-channel contamination measurement and display; measurement of international standard forms: ISO 4406:1999, NAS 1638, AS 4059E, and ISO 11218; data logging and 4000 test memory; PLC control across various communication protocols; alarm outputs; and certified zone II Cat 3 G rating. Water and temperature sensing provides early detection of corrosion, metal surface fatigue, reduced lubrication, and load-carrying characteristics. It is designed to be directly mounted to systems requiring ongoing measurement and analysis, or in high-risk environments.</p> <p><em><a href="http://www.mpfiltriusa.com" target="_blank">MP Filtri</a>, (215) 529-1300</em></p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/controls-instrumentation/fluid-condition-monitors#comments Controls & Instrumentation Hydraulic Fluids Tue, 11 Nov 2014 19:19:00 +0000 29621 at http://hydraulicspneumatics.com Ultra-fine filtered synthetic hydraulic oil http://hydraulicspneumatics.com/hydraulic-fluids/ultra-fine-filtered-synthetic-hydraulic-oil <div class="node-body article-body"><p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/Kl%C3%BCber-FB-4-fluid_0.jpg" style="width: 595px; height: 355px;" /></p> <p>Kl&uuml;bersynth FB-4 series ultra-fine filtered synthetic hydraulic oil extends component life and lowers operating cost. The series features three oils, ISO VG grades 32, 46, and 68. The series was designed to lubricate rolling bearings of high-speed machine tool spindles. It can be used in hydraulic systems and components including dirt-sensitive servovalves. The FB-4 series are PAO oils of purity class 15/13/10 in accordance with ISO 4406 and meet HLP requirements DIN 51524-2.</p> <p><em><a href="http://www.klueber.com" target="_blank">Kl&uuml;ber Lubrication</a>, (603) 647-4104</em></p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/hydraulic-fluids/ultra-fine-filtered-synthetic-hydraulic-oil#comments Hydraulic Fluids Tue, 11 Nov 2014 17:30:00 +0000 29611 at http://hydraulicspneumatics.com Electronic controllers offer drop-in replacement http://hydraulicspneumatics.com/controls-instrumentation/electronic-controllers-offer-drop-replacement <div class="node-body article-body"><p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/Divelbiss-Bear-Bones.jpg" style="width: 595px; height: 541px;" /></p> <p>The P-Series Bear Bones Controllers consists of open-board controllers, specialty function expanders, and I/O expanders. The series controller footprint is identical to the original Bear Bones series, making it a mechanical drop-in replacement. It features digital and analog I/O; CAN communication via OptiCAN, J1939, and NMEA 2000; Modbus TCP over Ethernet; LCD interface; keypad; and real-time clock. The I/O capabilities can be expanded by plugging in modules with eight digital inputs and outputs. Up to 31 I/O expanders may be connected and addressed to one controller. Controllers operate from ac or dc power.</p> <p><a href="http://www.divelbiss.com" target="_blank">DIVELBISS CORP.</a>,&nbsp; (800) 245-2327</p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/controls-instrumentation/electronic-controllers-offer-drop-replacement#comments Controls & Instrumentation Tue, 11 Nov 2014 14:49:00 +0000 29601 at http://hydraulicspneumatics.com