Hydraulics & Pneumatics - Hydraulics & Pneumatics is the leading international technical resource for fluid power http://hydraulicspneumatics.com/rss.xml en 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 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>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 A and B 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><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/Troubleshooting1.jpg" style="width: 595px; height: 446px;" /></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> <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>The unit piping had about &frac12; NPT and &frac12; 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> <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><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/Figure.gif" style="width: 595px; height: 739px;" /></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 The next chapter for the CCEFP http://hydraulicspneumatics.com/hydraulic-fluids/next-chapter-ccefp <div class="node-body article-body"><p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/Alan.jpg" style="width: 135px; height: 120px; float: left;" title="Alan Hitchcox, Editor in Chief" />I had been anticipating attending the Fluid Power Innovation &amp; Research Conference for months. So when mid-October finally arrived, it was off to Nashville. The conference was filled with technical presentations delivered primarily by students at schools that are part of the Center for Compact &amp; Efficient Fluid Power. (CCEFP).</p> <p>Of course, the event didn&rsquo;t involve just taking in presentations. There was plenty of time for networking, facility tours, and even some fun. The closing presentation was given by Eric Lanke, CEO of the National Fluid Power Association (NFPA), and Kim Stelson, Director of the CCEFP, who outlined how the CCEFP would continue onward once its primary funding from a National Science Foundation (NSF) grant expires next year.&nbsp; &nbsp;</p> <p>More than 50 companies support the CCEFP through funding and donations. Personally, I think the CCEFP is the best thing to happen to the North American fluid-power industry in 50 years. For about two decades after World War II, the US led the world in cooperative fluid-power research. Then within just a few years, research centers all but vanished throughout the US, whereas Europe had about 30.</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/next-chapter-ccefp-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>So, with the NSF grant funds soon to dry up, a plan had to be developed to replace that lost revenue. The solution described by Eric and Kim is the Pascal Society, created by NFPA&rsquo;s Education and Technology Foundation. The Pascal Society will combine the financial and volunteer contributions of a wide industry network into one concentrated effort to develop fundamental knowledge about fluid power, as well as educate the next generation of scientific and engineering leaders in the field.</p> <p>Two things about the presentation impressed me most. First, the entire program was well planned and detailed. I&rsquo;m one of the last people you&rsquo;d want to ask about finances. Yet, I understood what was explained, and it all made sense. Second, in this age where companies and organizations are understaffed and overworked, Eric, Kim, and their team were able to launch the Pascal Society well before the NSF cutoff date.</p> <p>If you have a moment, visit the <a href="http://www.ccefp.org/about-us" target="_blank">CCEFP</a> and the <a href="http://bit.ly/HP1411_Editorial" target="_blank">Pascal Society</a> online to learn more about them. A lot of companies spend a lot of money on research, but the CCEFP provides a means to combine efforts and resources to help ensure a strong future for fluid-power technology.&nbsp;</p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/hydraulic-fluids/next-chapter-ccefp#comments Hydraulic Fluids Tue, 11 Nov 2014 14:05:00 +0000 29581 at http://hydraulicspneumatics.com Pump Controls Optimize HPU Performance http://hydraulicspneumatics.com/hydraulic-pumps-motors/pump-controls-optimize-hpu-performance <div class="field-byline"> William Fischer, The Oilgear Co. </div> <div class="field-deck"> Through the proper selection of variable-volume pump control, the hydraulic system engineer can design a circuit that will offer the best performance with the most efficient use of available energy. </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/pump-controls-optimize-hpu-performance-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 function of a variable-displacement pump is to supply fluid flow to a hydraulic system at the rate required by the system. The control of fluid flow is achieved by moving the pump&rsquo;s swashplate, which, in turn, increases or decreases the pump&rsquo;s displacement. Ultimately, this increases or decreases flow from the pump to the hydraulic system. The movement of the swashplate position is accomplished using any of several different types of pump controls.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/2014.11-HPUs-LEAD-PVV540.jpg" style="width: 595px; height: 461px;" title="The ultimate in flexibility comes from servo-proportional pump control, where an external electronic control commands this PVV540 piston pump by making intelligent decisions about flow and pressure requirements." /></p> <p><strong>Volume and Pressure Control</strong></p> <p>The simplest pump control uses a mechanical link connected to the pump&rsquo;s swashplate to the stroke of the pistons. This can be as straightforward as a lever or a screw adjusted by hand to vary output flow from the pump.</p> <p>The most common pump control is pressure control. In this scheme, system pressure is monitored and automatically adjusts pump displacement to maintain a set point. Pressure compensation is often the choice for pressure control because it lets the pump stay at full stroke until pressure builds at the pump outlet port. Once the preset system pressure is achieved, the control automatically reduces pump displacement to allow just enough flow to maintain the desired pressure. As load flow demand changes, the pressure compensator responds by modifying the pump stroke to maintain the pressre setting. This type of control can be considered an on-demand flow system. With some types of pumps the user can select from multiple set points. This can be accomplished through the use of solenoid valves.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/HPUs_F1.gif" style="width: 595px; height: 335px;" title="Pressure compensation is an energy-saving control that decreases pump displacement as monitored pressure reaches a predetermined value." /></p> <p><strong>The Next Step</strong></p> <p>To take pressure control one step further entails monitoring the pressure drop across an orifice and adjusting the pump flow to maintain a constant differential pressure (∆P) across that orifice. The pressure drop across the orifice is monitored instead of the pressure at the load because the pressure drop across the orifice is proportional to the flow through it. So, maintaining a constant pressure drop ensures a constant flow. This function is called load-sense control.</p> <div class="related-content"> <div class="related-label"> Related</div> <p><a href="http://hydraulicspneumatics.com/200/TechZone/HydraulicPumpsM/Article/False/12020/TechZone-HydraulicPumpsM">Efficiency comes from Control</a></p> <p><a href=" http://hydraulicspneumatics.com/hydraulic-pumps-amp-motors/buses-pumps-and-local-versus-centralized-control">Buses, pumps, and local versus centralized control</a></p> <p><a href=" http://hydraulicspneumatics.com/200/TechZone/HydraulicPumpsM/Article/False/46094/TechZone-HydraulicPumpsM">Pump control vs valve control: Efficiency or performance?</a></p> </div> <p>The load-sense control will increase or decrease the output flow to maintain the preset ∆P across the load orifice. This means that regardless of load conditions or changes to the prime mover speed, the flow will remain constant for a given orifice opening. The load-sense control has the same maximum pressure setting as the straight pressure compensated control, but load sensing has a second set point. This type of control supplies only the flow required at whatever pressure is needed to do the work. The advantage is that the system only uses enough power to maintain proper flow.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/HPUs-Fig-2.gif" style="width: 595px; height: 470px;" /></p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/HPUs_F2a.gif" style="width: 595px; height: 460px;" title="This PVWJ076 piston pump (top) has its load-sense module highlighted in color, and the schematic shows that the load-sensing monitors pressure drops across an orifice to match pump displacement to maintain a constant ∆P." /></p> <p>Another type of pressure control is power limiting, which monitors the flow being delivered to a system and the system pressure. Pump stroke is modified to prevent the pressure-flow combination from exceeding a preset maximum power setting. If the system can run at lower pressure, the pump runs at full stroke (flow). However, as the pressure requirement increases, the power limiter reduces the flow available to the system. This control optimizes the pressure-flow combination for the specified maximum power.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/2014.11-HPUs-Fig-3.gif" style="width: 595px; height: 479px;" title="Power-limiting control regulates the combination of output flow and pressure to prevent power from exceeding a predetermined value. " /></p> <p>Pressure compensation, load sensing, and power limiting all can be implemented on the same pump to produce the most efficient pump operation. In this triple combination, the load-sensing function takes command until the flow-pressure combination meets the maximum power setting. At that point, the power-limiting function takes over until the maximum pressure of the compensator takes the pump to standby mode.</p> <p><strong>Into the Future</strong></p> <p>In today&rsquo;s world, higher efficiency with greater flexibility is the goal. As already mentioned, the right choice of mechanical pump controls can greatly influence the input power requirements. Adding electronic options adds a higher level of flexibility and control.<br /> The mechanical pressure compensator can have one, two, or three preset pressure settings selectable by solenoids. Replacing the screw adjustment for setting pressure with a proportional pressure-control valve provides infinite adjustments through a variable command voltage. This allows configuring the system on the fly in response to changing requirements.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/2014.11-HPUs-Fig-4-pvg130.jpg" style="width: 595px; height: 461px;" title="This PVG130 piston pump uses an electronic displacement control module to control output. The electronic control offers distinct advantages over mechanical controls and can communicate with a machine’s overall electronic control." /></p> <p>Another optional addition to the pressure compensator is the electronic displacement control (EDC). The EDC lets the operator adjust the pump stroke (flow) with a proportional command. This command can come from a joystick or an intelligent system controller. The proportional control commands the pump as long as the system pressure is below the pressure compensator setting. Once pressure exceeds the compensator setting, the mechanical control overrides the EDC valve to reduce the pump stroke. This control can be configured so that a loss of the electronic command signal still allows the pump to perform as a pressure-compensated pump.</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/pump-controls-optimize-hpu-performance-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 ultimate flexibility comes through the use of a servo-proportional control. In this configuration, the mechanical control is replaced with a servo or proportional valve. Any change in pump command must come from an external electronic system. This system can monitor all feedback and safety devices on equipment to make intelligent decisions about the flow and pressure requirements to command the pump accordingly.</p> <p><em>Bill Fischer is Piston Pump Product Manager at <a href="http://www.oilgear.com" target="_blank">The Oilgear Co.</a>, Milwaukee. For more information, call (414) 327-1700.</em></p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/hydraulic-pumps-motors/pump-controls-optimize-hpu-performance#comments Controls & Instrumentation Hydraulic Pumps & Motors Mon, 10 Nov 2014 22:03:00 +0000 29571 at http://hydraulicspneumatics.com Hydraulic Equipment Reliability: Who's Responsible? http://hydraulicspneumatics.com/blog/hydraulic-equipment-reliability-whos-responsible <div class="node-body blog-body"><p>I got this beef from the Chairman of an association of contractors in a particular industry in a European country (all of whom shall remain nameless to protect their identity):<br /> <br /> <em>&quot;We depend heavily on hydraulic equipment. Our problem is that the manufacturers seem to make machines to sell components and not for reliability. So they don&#39;t provide any information regarding reducing breakdown of working hydraulics and how to avoid the same. Also, they charge unreal prices for replacement parts and they have agreements with manufactures of pumps and motors to give no information on replacements at a cheaper cost... I was very impressed on reading your &#39;<a href="http://www.hydraulicsupermarket.com/track?p=handp&amp;w=smr">Six Costly Mistakes report&#39;</a>.&quot;</em><br /> <br /> In many respects the conflict between machine maker and machine owner is a classic duality - similar to that which exits between labor and capital: The owners of labor (workers) want more pay, better conditions, few working hours, etc. While the owners of capital (businesses) want the exact opposite - or at least their interests are best served by the exact opposite of what their workers want.<br /> <br /> Similarly, a machine owner wants a machine that is cheap to buy, is maintenance free, highly reliable and cheap to fix when it does breakdown. But just like the owners of capital, the machine makers&#39; interests are best served by the exact opposite of what the machine owners want.<br /> <br /> In both conflicts: labor/capital and machine owner/maker, an acceptable compromise has to found between the two parties. But this compromise is not always in the middle. If the labor union movement is allowed to become too powerful, they can hold sway over the owners of capital. Conversely, if the owners of capital become too powerful, they can exploit their workers. In short, the power balance can shift one way or the other, and is rarely static.<br /> <br /> Clearly the above comments from the industry association Chairman reflect the fact that he feels his members are being exploited - that machine makers have &#39;the wood&#39; over machine owners. But it doesn&#39;t have to be this way.<br /> <br /> <em>&quot;Manufacturers seem to make machines to sell components and not for reliability.&quot;</em><br /> <br /> More often than not, machine manufacturers make machines to a price. Mainly because this is the criteria machine owners buy on. And if the machine owner buys on price, why should the manufacturer be overly concerned with reliability? Because at the end of the day, that&#39;s largely the machine owner&#39;s problem.<br /> <br /> <em>&quot;...they don&#39;t provide any information regarding reducing breakdown of working hydraulics and how to avoid the same.&quot;</em><br /> <br /> This probably sounds smug, but if the machine manufacturer really had this expertise, they would build as much of it as they could afford to into their designs. If you&#39;ve followed what I&#39;ve said so far about the conflicting interests of machine owner and maker, I&#39;d say it&#39;s the machine owners&#39; job to educate the machine maker - not the other way round.<br /> <br /> This means machine owners need to get a lot smarter - both technically and commercially when making hydraulic equipment purchases. And only by buying machines based on a more sophisticated selection process than just initial capital cost, will machine makers be forced to sit up and take notice.<br /> <br /> I&#39;m always amazed that most hydraulic equipment owners pay such little attention to this. And when you consider the amounts of money involved, my <a href="http://www.hydraulicsupermarket.com/track?p=handp&amp;w=hbpbsp">Hydraulic Breakdown Prevention Blueprint</a> should be my best-selling product, but frankly, it is not.<br /> <br /> Last weekend I had to go out and buy a new desktop printer. So I looked at all the options, and the prices ranged between $50 and $200. After narrowing the field down to two which would serve my purposes - a $54 dollar unit and a $79 unit, I then walked over to where the replacement ink cartridges were on display.<br /> <br /> Of course, it&#39;s not just the PRICE of the replacement ink cartridge which is important, it&#39;s also how many pages (or photos) you get out of it for the money. Obviously, by doing this simple exercise, I chose my new printer based on life of ownership cost, not just initial capital cost.<br /> <br /> And you don&#39;t have to be a genius to figure out, that just like hydraulic equipment manufacturers, desktop printer manufacturers make their money on replacement parts. The black ink cartridge for the $54 printer I ended up buying is $59.95!<br /> <br /> When it comes to buying hydraulic equipment, the amount of money, the technical issues involved and the level of analysis required are different, but the principle is EXACTLY the same. <strong>Bottom line</strong>: buying a hydraulic machine based on initial capital cost, without considering life of ownership cost, 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/hydraulic-equipment-reliability-whos-responsible#comments Hydraulics At Work Mon, 10 Nov 2014 21:44:00 +0000 29561 at http://hydraulicspneumatics.com Deep Seas Push Hydraulic-System Boundaries http://hydraulicspneumatics.com/marine-offshore/deep-seas-push-hydraulic-system-boundaries <div class="field-byline"> Royce Gerngross and Alexandre Orth, PhD </div> <div class="field-deck"> Industries expand efforts into the subsea terrain to acquire vital resources needed to meet global demand. </div> <div class="node-body article-body"><p>More than two-thirds of the earth&rsquo;s surface is covered by water, and many potential resources in those depths await exploration and development. Industries involved in this new frontier include mining, oil and gas, infrastructure, energy generation, and natural science.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/Lead-image_web.jpg" style="width: 595px; height: 629px;" title="Remote-operated and underwater autonomous vehicles make extensive use of hydraulics for its high power density and reliability. Hydraulics technology not only provides power for work functions, but actuation systems create a more compact vehicle for easier deployment and recovery." /></p> <p>These activities all involve complex and highly technical systems. Many of them&mdash;particularly those performed beneath the sea&rsquo;s surface&mdash;use a broad array of electrohydraulic systems to lower and lift equipment to the seabed, remote-operate subsea systems, and permanently monitor emplaced systems (e.g., petroleum wellheads or communications cables).</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/deep-seas-push-hydraulic-system-boundaries-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>Such hydraulic equipment often is assumed to be specifically designed and engineered using special materials for operation under the high pressures and corrosive conditions of different sea depths. However, with sufficient customization, many standard hydraulic systems designed for surface use can operate effectively in this demanding environment.</p> <p>Ultimately, the operation of any hydraulic system requires isolating the hydraulic circuit from external environments and controlling the fluid to perform work. The principles are the same; therefore, the design principles for subsea simply call for considering additional conditions.</p> <p><strong>Comparison of Subsea Requirements</strong></p> <p>Selecting the best solution for a given application requires understanding how the different subsea water depths impact the hydraulic system. The analyses used in oil and gas exploration supply an effective set of guidelines.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/marine_offshore_table.gif" style="width: 595px; height: 294px;" /></p> <p>At depths to 1,000 ft. (305 m), components must operate in salt water, but not in significantly high water pressures. The equipment is relatively easy to operate, put in place, and retrieve. However, sunlight may penetrate up to 200 m, thus promoting the growth of sea life over the equipment surface. This must be factored into designs of components such as piston rods in hydraulic cylinders.</p> <p>In depths from 1,000 to 6,000 ft. (305 to 1,830 m), hydrostatic pressure becomes a major concern. Water pressure increases about 1 bar (14.5 psi) for every 10 m of depth. Consequently, at 5,000 m (16,400 ft), the ambient pressure will be 500 bar (7,250 psi). At these depths, all work is done with remote-control systems and subsea robots, such as remote operated vehicles (ROVs) and autonomous underwater vehicles (AUVs).</p> <div class="related-content"> <div class="related-label"> Related</div> <p><a href="http:///hydraulicspneumatics.com/marine-amp-offshore/great-ascent">The great ascent</a></p> <p><a href="http:///hydraulicspneumatics.com/200/TechZone/Cylinders/Article/False/84846/TechZone-Cylinders">Laser coating helps rods stand up to harsh marine environments</a></p> <p><a href=" http://hydraulicspneumatics.com/hydraulic-fluids/offshore-operator-commits-biodegradable-hydraulic-fluid">Offshore operator commits to biodegradable hydraulic fluid</a></p> </div> <p>Components exposed to these high external water pressures may require special design features, such as pressure compensation or structural modifications. These depths are typically encountered far from shore, requiring floating platforms or ships and platforms, which create additional challenges.</p> <p>Aside from military and research vessels, there&rsquo;s little experience with subsea equipment in ultra-deep water&mdash;from 6,000 to 35,800 ft. (1,830 to 10,900 m). As depths increase, even the engineering of hoisting and tether equipment construction must change to accommodate the dimensions and weight of the systems as they increase with the water depth. Furthermore, the ocean conditions become harsher, such as the size of waves or the forces caused by maritime currents.</p> <p><strong>Robotics: The Subsea Enabler</strong></p> <p>Because divers cannot operate beyond a depth of 100 m, the bulk of subsea activities must be performed by ROVs and AUVs, complex systems that use extensive electromechanical and electrohydraulic subsystems to accomplish tasks. Though their operational depths can be in any range, robots typically aren&rsquo;t submerged for long periods of time. However, it&rsquo;s critical they are ready when needed, and if they malfunction, the downtime must be kept to a minimum.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/2nd_image.gif" style="width: 595px; height: 235px;" title="A pressure-compensation system exposes hydraulic fluid within the reservoir to ambient hydrostatic pressure, but a flexible seal prevents seawater and hydraulic fluid from contacting each other." /></p> <p>The advantages of hydraulic drives really come to light in these machines: They are powerful, compact, precise, intelligent, and rugged, providing excellent power density and adroit flexibility for a wide range of tasks. That said, ROV and AUV developers continue to seek more sophisticated performance and reliability from these integrated electrohydraulic systems.</p> <p><strong>Subsea Design Requirements</strong></p> <p>Successful growth of many subsea applications depends on how long equipment can be reliably and safely deployed and operated without requiring overly expensive engineering, operating, and repair costs. Some built-in costs for subsea work are unavoidable&mdash;operating equipment at a distance with remote devices, and dealing with external water pressure, currents, and corrosion conditions. Careful planning and a willingness to integrate smart design principles into subsea hydraulic systems make it possible to cost-effectively accomplish these goals.</p> <p>Pressure compensation is useful in any system that operates underwater. It&rsquo;s used to keep the pressure between external environment (seawater) and reservoir constant, because seals are typically designed for a limited pressure drop in one particular direction. Most components readily available were designed for operation in normal surface environments. Almost all machines have sealing surfaces or other parts that cannot withstand high subsea external pressures or severe pressure drops.</p> <p>Although complicated and expensive, one option is to seal pressure-sensitive components inside a protective chamber. This usually involves a container with rigid construction and heavy-duty seals to withstand the high external pressures. A more effective solution, however, is pressure compensation. With this technique, a pressure is applied inside the component that&rsquo;s equal and opposite to the ambient pressure outside.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/Third-image.gif" style="width: 595px; height: 170px;" title="High velocity oxygen fuel (HVOF) gun and cobalt-alloy coatings applied via plasma arc welding are two coating types that improve tribological properties of piston rods in underwater-bound large hydraulic cylinders." /></p> <p>In a typical hydraulic system, the standard reservoir is replaced with a sealed reservoir containing a flexible medium separator. Therefore, the external environment pressure transfers to the reservoir, just as a normal surface system has the external air pressure on top of the oil in the reservoir. The difference is that it prevents the seawater from mixing with the oil.</p> <p>This clever system allows any component used on the surface to be used subsea, as long as all volumes that normally contain air can be vacated of air filled with fluid and connected to the reservoir to maintain the pressure balance.</p> <p><strong>Corrosion Protection and Sealing</strong></p> <p>Offshore machines typically have a seal, sealing surface, seawater, and some other medium in contact and interacting with each other. The study of these items is known as tribology. Knowledge of this is critical for system designers, to both keep seawater out of a system and keep the hydraulic fluid in. On large hydraulic cylinders, for example, maintaining the integrity of the piston rod, which is routinely exposed to environmental conditions in operation, is essential for maintaining long-term operating life of the system.</p> <p>No matter what the application, though, hydraulic-cylinder design always involves an interaction between seals, fluid, and material surface. The cylinder&rsquo;s piston rod surface needs an appropriate coating to provide a good and durable base for its tribological system. Major advances have occurred in cylinder coating technologies, including metallic/metal mix systems applied with high velocity oxygen fuel (HVOF) or cobalt-alloy coatings applied via plasma arc welding.</p> <p><strong>Designing for Safety and Reliability</strong></p> <p>Equipment engineered for subsea applications must protect both people and the ocean environment from any damage. For deep water and ultra-deep water operations, surface operators need protection from equipment failures during the whole lifecycle of the subsea system.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/11/Fourth-image_web.jpg" style="width: 300px; height: 326px; float: left;" title="This valve manifold is an example of packaging that adapts otherwise standard electrohydraulic valves for use in the extreme ambient pressure, highly corrosive environment encountered in deep-sea applications. " /></p> <p>Subsea operations are carried out in environmentally sensitive areas. Most hydraulic systems must adhere to specific safety standards, such as fail-safe operation. Therefore, if the power supply is cut off, this de-energization principle causes the hydraulic system to automatically shift to a safe position. These principles of risk assessment and functional safety have been established through international standards such as ISO 12100, ISO 13849, and ISO 4413.</p> <p>The reliability of subsea equipment with a projected 30-year lifetime, operating in such a harsh environment, represents one of the biggest challenges for the industry today. Reliable hydraulic-system design for subsea applications can apply different approaches at the same time:</p> <p>&bull; Use highly reliable components. A reliability indicator should be used to compare parameters like mean time to failure, B10 life, or Weibull distributions.<br /> &bull; Cost-effective redundant architecture can be installed for higher system reliability. In some cases, more than two components may be needed to support each other.<br /> &bull; Integration of failure diagnostic features, such as suitable sensors and algorithms to process their information, can detect a failure and decide the appropriate corrective reaction.</p> <p>Field operators in oil and gas applications expect minimal maintenance from subsea equipment during a well location&rsquo;s entire service life, which can be 30 years or more. Suitable sensors must be designed, integrated and pressure-proven to detect failures and, if possible, anticipate future failures by including condition monitoring functions.</p> <p>As industries move deeper into the ocean, fundamental technical challenges increase, particularly for hydraulically driven systems. These challenges can be met through a combination of standard, off-the-shelf components proven to operate in rugged conditions on the land, with suitable adaptations and smart, cost-effective application of more advanced materials where needed. This approach can ultimately deliver more cost-effective subsea development and wider access to the potential resources offered by this emerging frontier.</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/deep-seas-push-hydraulic-system-boundaries-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><em>Royce Gerngross is Engineer, Marine &amp; Offshore, and Alexandre Orth, PhD, is Project Risk Manager at <a href="http://www.boschrexroth-us.com" target="_blank">Bosch Rexroth AG</a>., Lohr, Germany. </em></p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/marine-offshore/deep-seas-push-hydraulic-system-boundaries#comments Marine & Offshore Hydraulic Pumps & Motors Mon, 10 Nov 2014 19:08:00 +0000 29541 at http://hydraulicspneumatics.com Hydraulics in the Aftermath of Pearl Harbor http://hydraulicspneumatics.com/blog/hydraulics-aftermath-pearl-harbor <div class="node-body blog-body"><p>I&#39;ve been working on my next series of blogs about a column we used to run called &quot;Circuit of the Month.&quot; I found a few of them, but I want to have them all accounted for before I begin the series.</p> <p>In the meantime, it&#39;s hard to resist looking through some of the old issues for nuggets of interesting and useful information. If found one in our first issue, from February 1948. Many of the issues in the late 1940s and early 1950s had frequent references to patriotism and WWII. The article I&#39;m reproducing here describes some of the salvage efforts to raise the USS California and others after they were sunk or capsized at Pearl Harbor on December 7, 1941. I find it especially interesting how quickly things got done. Here is the article, pretty much as it appeared nearly 70 ears ago:</p> <h3> <strong>Remember Pearl Harbor</strong></h3> <p><a href="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/uploads/2014/11/194802-pearl-harbor.jpg"><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/1948.02-Pearl%20Harbor.jpg" style="width: 300px; height: 215px; float: right; margin-left: 4px; margin-right: 4px;" title="With long-boomed cranes assisting and salvage pumps building buoyancy, the battleship &quot;California&quot; rises to the surface of Pearl Harbor. (Click on image for larger view.)" /></a>THE DAMAGE at Pearl Harbor &mdash; eight battleships and ten other warships sunk or disabled &mdash; called for one of the most urgent salvage jobs in history. The most critical part of the salvage was to clear the entrance channel of the harbor. The securing of cables, the enormous lifting power required and the delicacy of the actual lifting and righting of 30,000-ton hulks called for more large, specially equipped cranes and hoists than the entire Navy possessed. Industry rose to the occasion.</p> <p>Six of the cranes or hoists used for the job were Manitowoc Model 3000 cranes with a 50-ton capacity at a 12-foot hoisting radius. All six cranes were hydraulic torque converter equipped. The <strong><a href="http://www.manitowoccranes.com/" target="_blank">Manitowoc Engineering Works, Manitowoc, Wisc.</a></strong>, had three converters installed on completed cranes awaiting shipment. The converters were immediately stripped from the completed cranes and installed in the 50-ton cranes required by the Navy. The first crane was actually shipped within a week. One converter each was shipped on January 3, 6 and 9, which permitted Manitowoc to ship their last unit within six weeks after receipt of the order from the Navy Department.</p> <p>The salvage job was complicated by the fact that several battleships lay in forty to sixty feet of soft mud. It was necessary to run cables around the hulls and hold the dead weight of the water-filled ships while the mud was sludged away, emergency repairs made, the holds pumped clear and the delicate raising and righting operations completed.</p> <p>This operation involved torque converter-equipped hoists produced by the Winch and Hoist Division of Six Wheels, Inc., Los Angeles. Six Wheels, Inc. placed an order on December 16, 1941, for twelve hydraulic torque converters supported by a AA priority rating. Seven of the converters were shipped before the end of the month, and the balance of five units went forward the week of January 5th, making it possible for Six Wheels, Inc. to make delivery of their salvaging hoists in record time.</p> <p>The splendid job that Six Wheels, Inc. did in delivering the twelve salvaging hoists to the Navy had one interesting background incident, which is released now for the first time. One day in November, 1940, a naval salvage engineer walked into the Six Wheels Inc., office. He laid down specifications for a hoist that was to be powered by an internal combustion engine, but which had to exhibit the power ability and smoothness characteristic of a steam generated unit and with all load shocks (characteristic in cable, gears and chain) eliminated. The engine had to act as a steam throttle throughout the entire torque-speed range. The overall dimensions had to be held to the minimum width, height and length. The total weight was restricted to 10,000 pounds for each hoist. Each unit, consisting of not more than four parts, which could not exceed 3300 pounds each. An essential specification was that the complete hoist be assembled and disassembled into four parts in one-and-a-half hours.</p> <p>The design, taking the sacrifice of weight and other normal safety factors into consideration, required the very finest materials in construction to ensure 100 percent performance. The officer&#39;s closing statement summed up the urgency. &ldquo;We do not have a second chance to come back &mdash; <em>It&#39;s now </em><em>or </em><em>never</em>.&quot;</p> <p>Six Wheels, Inc., accepted the challenge and was given the go-ahead on three units. Experience gained with these units made the delivery of the first twelve hoists at Pearl Harbor possible in record time.</p> <p>Although the story is almost forgotten, the torque converter was one of the first jobs that went to war.</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/hydraulics-aftermath-pearl-harbor#comments Marine & Offshore Material Handling Hydraulic Pumps & Motors The Hitch Post Sat, 08 Nov 2014 17:24:00 +0000 29521 at http://hydraulicspneumatics.com The Difference Between A Quick Fix And A Band-Aid Solution http://hydraulicspneumatics.com/blog/difference-between-quick-fix-and-band-aid-solution <div class="node-body blog-body"><p>Last week I had a conversation with an old client who&#39;s been having a long-running battle with the manufacturer of a hydraulic machine he bought 3-years ago. The machine has never performed to either my client&#39;s satisfaction or the manufacturer&#39;s advertised specifications. This client is an owner/operator, which means his machine is his livelihood. And he&#39;s had enough. So now he&#39;s taking the machine&#39;s manufacturer to court, a decision he hasn&#39;t taken lightly.<br /> <br /> Although he didn&#39;t consult me directly about this issue, I was aware of the problems he was having, and the way in which the equipment manufacturer was responding to them. The crux of the issue, and one which will now be argued in court, is the machine model my client bought was marketed as a &#39;professional&#39; version, meaning it was designed to be used a minimum 8 hours a day, 5 days a week. As opposed to hobbyist or weekender use of typically, a couple of hours in a stretch, a couple of days a week.<br /> <br /> Trouble is, when the &#39;professional&#39; model my client purchased was operated continuously for more than a couple of hours, its performance dropped off dramatically. And the primary reason for this, which was blatantly obvious to me, was insufficient installed cooling capacity. Or more accurately, NO installed cooling capacity at all.<br /> <br /> Not only did I share this assessment with my client, but because I&#39;d done work for him before and didn&#39;t want to see him lose work and income as a result of the machine&#39;s obvious design flaw, I presented him with a Band-Aid solution: switch to a high VI, synthetic oil.<br /> <br /> Now don&#39;t get me wrong. I&#39;m all for doing things right. The correct solution to this issue is/was to install a heat exchanger of sufficient capacity to maintain an appropriate and stable operating oil temperature, and therefore, viscosity. But in this case, there were two major barriers to this happening. The first is the compact nature of the machine means there is little or no space to retrofit a hydraulic oil cooler. And the second is my client quite rightly expected the machine manufacturer to do this under warranty. And this meant the OEM had to admit the machine had a design flaw. &nbsp;<br /> <br /> Switching to a high VI, synthetic oil does nothing to address the issue of insufficient cooling capacity-it just helps the machine to cope with it. So in this respect, it definitely qualifies as a Band-Aid solution.<br /> <br /> Unfortunately my client didn&#39;t act on this advice. Maybe it was because, despite the apparent widespread popularity and seductive appeal of the quick-fix, we&#39;ve been conditioned to think of Band-Aid solutions in negative terms. In his book The Tipping Point, author Malcolm Gladwell describes it this way:<br /> <br /> <em>&quot;But that phrase [Band-Aid solution] should not be considered a term of disparagement. The Band-Aid is an inexpensive, convenient and remarkably versatile solution to an astonishing array of problems. In their history, Band-Aids have probably allowed millions of people to keep working or playing tennis or cooking or walking when they would otherwise have had to stop. The Band-Aid solution is actually the best kind of solution because it involves solving a problem with the minimum amount of effort and cost. We have, of course, an instinctive disdain for this kind of solution because there is something in all of us that feels that true answers to problems have to be comprehensive, that there is virtue in the dogged and indiscriminate application of effort, that slow and steady should win the race. The problem, of course, is that the indiscriminate application of effort is something that is not always possible. There are times when we need a convenient shortcut, a way to make a lot out of a little...&quot;</em><br /> <br /> This negative bias towards the Band-Aid solution in engineering is particularly strong. And in many situations, rightly so. But for a mini-digger with a chronic overheating problem, and which for physical and political reasons is not easily corrected, being open to a Band-Aid solution can be very constructive.<br /> <br /> Like I said earlier, I&#39;m all for doing things the right way. And I consider quick-fix, silver bullet, magic-pill-cure-all solution seeking as lazy and unrealistic. But as Gladwell says: <em>&quot;There are times when we need a convenient shortcut...&quot;</em> The trick is being able to recognize when a Band-Aid solution is appropriate, and when it is not.<br /> <br /> I wish this client the best of luck with his law suit. He deserves to win. But more than that, having declined the Band-Aid solution, now he has to win. The other important point this story illustrates is, allowing a hydraulic machine to run hot is a costly mistake. To discover six other costly mistakes you want to be sure to avoid with your hydraulic equipment, get <a href="http://www.hydraulicsupermarket.com/track?p=handp&amp;w=smr">&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/difference-between-quick-fix-and-band-aid-solution#comments Hydraulics At Work Mon, 03 Nov 2014 21:45:00 +0000 29501 at http://hydraulicspneumatics.com Solenoid Valves http://hydraulicspneumatics.com/hydraulic-valves/solenoid-valves <div class="field-deck"> Sponsored by Peter Paul Electronics </div> <div class="node-body article-body"><p>What are the common functions of solenoid valves? What is the port size? What voltage does a solenoid need to operate the valve? What size orifice or flow is required?<br /> <br /> Download the <b><i>FAQs of Solenoid Valves</i> sponsored by Peter Paul Electronics</b> to answer these questions and more.<br /> <br /> <script type="text/javascript">(function(n){var r="_ion_ionizer",u="//1f1835935797600af226-51128641de34f0801c2bd5e1e5f0dc25.r5.cf1.rackcdn.com/ionizer-1.0.min.js",t=n.getElementsByTagName("script"),i;t=t[t.length-1],t.id=r+ +new Date+Math.floor(Math.random()*10),t.setAttribute("data-ion-embed",'{"url":"//reg.hydraulicspneumatics.com/HP-WP-PeterP-Solenoid-Valve-103114?_ion_target=embed-1.0","target":"'+t.id+'","appendQuery":false}'),n.getElementById(r)||(i=n.createElement("script"),i.id=r,i.src=n.location.protocol==="https:"?u.replace(".r5.",".ssl."):u,t.parentNode.insertBefore(i,t.nextSibling))})(document);</script></p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/hydraulic-valves/solenoid-valves#comments Design FAQs Hydraulic Valves Pneumatic Valves Fri, 31 Oct 2014 19:34:00 +0000 29491 at http://hydraulicspneumatics.com Hydraulic Conductor Face Off: Hose vs Tube http://hydraulicspneumatics.com/blog/hydraulic-conductor-face-hose-vs-tube <div class="node-body blog-body"><p>What do lifting chains, bladder-type accumulators and hydraulic hoses all have in common? Well, they typically have only one mode of failure - and that&#39;s catastrophic. One minute they&#39;re working as they should and the next thing you know, they&#39;ve gone to hell.<br /> <br /> Oh sure, hoses can leak from around their ferrules and show obvious signs of abrasion, both of which are early warning signs that a change-out would be prudent. But even under these conditions, estimating their remaining service life is virtually impossible.<br /> <br /> <strong>The Trouble With Hose</strong><br /> <br /> Beyond the fact that their service life is finite and difficult to estimate, other disadvantages of hydraulic hoses when compared to tube include:</p> <ul> <li> They expand and stretch under pressure. This flexing requires extra volume and adds to machine cycle time.</li> <li> They typically have a limited operating temperature range.</li> <li> Their requirement for regular replacement makes them a source of contaminant ingression.</li> <li> They are expensive.</li> </ul> <p>Despite the above disadvantages, hoses are a necessary feature of most hydraulic systems. This is because the alternative conductor - tube, cannot be used where:</p> <ul> <li> There is limited space (particularly in mobile hydraulics).</li> <li> There is relative movement between machine components and superstructure.</li> <li> Noise and vibration need to be suppressed.</li> </ul> <p>However, hose is often substituted for tube when it&#39;s not necessary. This is because a hose assembly can usually be fabricated much faster than a tube assembly. And the additional labor cost required to fabricate and install a tube, can make a hose appear to be the cheaper solution.<br /> <br /> But this ignores the fact that the same hose may need to be replaced many times, over the life of the machine. This false economy is similar to buying the machine itself on initial capital outlay alone - without considering its total life-of-ownership cost.<br /> <br /> <strong>Tube Is Cool</strong><br /> <br /> And tube has some compelling advantages of its own. One of these is its superior heat transfer - especially if it&#39;s painted. One aspect of heat transfer is thermal radiation. The total radiation from an object is the sum of its reflection, emissivity and transmission of heat through the object. When hydraulic tube is painted, it reduces its reflectance and increases its emissivity, enabling better heat rejection.<br /> <br /> In summary, hydraulic hose and tube are not interchangeable; they&#39;re different &#39;tools&#39; for different jobs. The benefits of hose, which make it a necessary feature of most hydraulic machines, come at a cost. It has a finite service life and usually gives no warning of failure. This makes it a difficult maintenance item to manage. For these reasons, substituting hose for tube is usually a mistake. And to discover six other costly mistakes you want to be sure to avoid, <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/hydraulic-conductor-face-hose-vs-tube#comments Hydraulics At Work Mon, 27 Oct 2014 21:21:00 +0000 29481 at http://hydraulicspneumatics.com FSA Appoints Three New Board Positions http://hydraulicspneumatics.com/news/fsa-appoints-three-new-board-positions <div class="field-byline"> Sarah Mangiola </div> <div class="node-body article-body"><p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/Mike%20Shorts%20Headshot.jpg" style="width: 150px; height: 141px; float: right; margin: 3px;" title="President of the Board of Directors, Michael Shorts. (Courtesy of the FSA)" /></p> <p>Michael Shorts has been appointed as President of the Board of Directors for the Fluid Sealing Association (FSA). Currently an active member of the FSA, serving as Chair of the Membership Committee and sitting on several other committees, Shorts is also currently Vice President and General Manger for Triangle Fluid Controls Ltd. in Belleville, Ontario, Canada. Additionally, he is the International Business Development Manager for TFC.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/Phil%20Mahoney.jpg" style="width: 125px; height: 167px; float: left; margin: 3px;" title="VP of the Board of Directors, Phil Mahoney. (Courtesy of the FSA)" />Phil Mahoney is the new Vice President of the Board of Directors. Currently the Design Engineering Manager for Compression Packing and Mechanical Seals for the A.W. Chesterton Company in Groveland, MA, he is also the FSA Vice Chair of the Membership Committee, a member of the Government Affairs Working Group, the Marketing Committee, and the Technical Coordinating Committee. He has been active with FSA since 2004.</p> <p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/RobCoffee2.jpg" style="width: 125px; height: 187px; float: right; margin: 3px;" title="Board of Directors, Robert S. Coffee. (Courtesy of the FSA)" />Additionally, Robert S. Coffee has been appointed to the Board of Directors. He is the Vice President of Sales and Marketing for Proco Products, Inc., in Stockton, California. He is currently serving the FSA as a member of the Marketing and Membership Committees.&nbsp;</p> <p>&nbsp;</p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/news/fsa-appoints-three-new-board-positions#comments Seals News Tue, 21 Oct 2014 15:43:00 +0000 29471 at http://hydraulicspneumatics.com HAWE Hydraulics North America welcomes new CEO http://hydraulicspneumatics.com/news/hawe-hydraulics-north-america-welcomes-new-ceo <div class="node-body article-body"><p><img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/Chad%20Tuttle%2C%20CEO%20NA.jpg" style="width: 152px; height: 184px; float: right; margin-left: 4px; margin-right: 4px;" title="Tuttle" /><a href="http://www.haweusa.com/" target="_blank">HAWE Hydraulics</a>, Charlotte, N.C., announced that Chadwick Tuttle has been selected as the new General Manager and CEO for the North American operations of <a href="http://www.hawe.de" target="_blank">HAWE Hydraulik SE</a>, Munich. A news release form HAWE Hydraulics mentioned that Tuttle&#39;s selection &quot;is a clear demonstration of our confidence in his skills and reflects our belief that we are on track to become the global leader in fluid power.&quot;</p> <p>Tuttle brings extensive experience in international fluid handling. Prior to HAWE, Tuttle held high responsibility positions in <a href="https://www.gouldspumps.com" target="_blank">ITT Goulds Pumps</a> and <a href="http://www.spx.com/en/clydeunion-pumps/" target="_blank">Clyde Union Pumps</a>. The news release also expalined, &quot;His particular skills set will be most beneficial for the overall vision of the company, and we are enthusiastic to have Chad join our team!&quot;<br /> <br /> HAWE Hydraulik entered the North Americal martket in 1997 through its North American subsidiary HAWE Hydraulics. Today, the partnership brings more than 60 years of German engineering and experience to North American mobile and industrial markets. HAWE provides integrated services that include design, manufacture, set-up, a distributor network, and local inventory. Based in Charlotte, HAWE has divisions in Portland, Oreg. and Houston. HAWE Hydraulik is an ISO 9001:2001 certified international supplier with a strong focus on supporting rapidly developing niche markets.</p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/news/hawe-hydraulics-north-america-welcomes-new-ceo#comments News Mon, 20 Oct 2014 13:15:00 +0000 29451 at http://hydraulicspneumatics.com Who DO you trust with YOUR hydraulic machine? http://hydraulicspneumatics.com/blog/who-do-you-trust-your-hydraulic-machine <div class="node-body blog-body"><p>One of my <a href="http://www.hydraulicsupermarket.com/pro-club.html">Hydraulics Pro Club</a> members, who I&#39;ll call John (not his real name) wrote me his story:<br /> <br /> <em>&quot;I&#39;m an owner/operator of a small concrete pumping business. We have 12 years experience operating concrete pumps but limited knowledge of hydraulics. I have no faith in the manufacturer&#39;s dealer. They don&#39;t give away any information and I&#39;m not happy with the work they do. Plus, they&#39;re 6 hours away.<br /> <br /> So I need to gather my own information on hydraulics to become more self sufficient. For example, I&#39;m currently trying to diagnose a problem which I wasn&#39;t aware I had until the manufacturer pointed it out during my last annual boom inspection.<br /> <br /> I&#39;m not sure, but I think the machine has been doing it the whole time we&#39;ve owned it, which is 5 years. When the machine is sitting idling, the swinger-ram pressure is fluctuating between 1200 PSI and 1500 PSI. I&#39;ve asked them what the problem could be. They say: &#39;Bring it in. We need to go through the whole system. Probably a leaking o-ring somewhere.&#39; For reasons already stated, I&#39;m not keen to take the machine to them, with a free hand to &#39;go through the whole system&#39;.&quot;</em><br /> <br /> It&#39;s understandable that John is wary about taking his machine to the dealer. After all, entrusting your livelihood to a bunch of grease monkeys of unknown ability requires a BIG leap of faith. Especially when you consider that, according to the Fluid Power Safety Institute, 98% of people who service, repair and maintain hydraulic systems are not properly trained.*<br /> <br /> So John has good cause to wonder: who is going to be working on my hydraulic machine and do they really know what they&#39;re doing? In other words: can I trust them?<br /> <br /> I&#39;m not a concrete pump expert, but I told John the swinger circuit usually features an accumulator. In which case it would be normal for the pump to unload at 1500 PSI and reload to charge the accumulator when pressure drops to 1200 PSI. That said, if the pump and accumulator are cycling rapidly between 1200 and 1500 PSI, this indicates the accumulator&#39;s gas-end needs attention, or there&#39;s an oil leak in the accumulator circuit.<br /> <br /> It would&#39;ve been no skin off the dealer&#39;s nose to share this insight with John. In fact, it would have given John confidence that they do know what they&#39;re talking about. Trouble is, maybe they DON&#39;T. And that&#39;s the problem for machine owners like John.<br /> <br /> The upshot of all this is, if you don&#39;t do your homework when choosing a hydraulic repair shop, it can cause a lot of heartache. Unfortunately, like most other industries, the hydraulics biz has its share of shoddy and incompetent operators. In chapters 14, 15 and 16 of <a href="http://www.hydraulicsupermarket.com/track?p=handp&amp;w=isthsp">&#39;Insider Secrets to Hydraulics&#39;</a>, I deal with this subject at length: how to choose a hydraulic repair shop; the things to look for when you do; and how to avoid being taken for a ride.<br /> <br /> For me though, the BEST part is knowing <a href="http://www.hydraulicsupermarket.com/track?p=handp&amp;w=isthsp">Insider Secrets</a> is helping hydraulic equipment users, both large and small, all over the world -- something it&#39;s being doing for 12 years now, and counting. In the words of legendary success coach, author and speaker, Jim Rohn:<br /> <br /> <em>&quot;A book is the best investment anyone can make because someone puts 30 years of their life experience into 300 pages and sells it for $30.&quot;</em><br /> <br /> &#39;Insider Secrets to Hydraulics&#39; is this type of book. If you own or are responsible for the upkeep of hydraulic equipment, and you haven&#39;t read it yet, <a href="http://www.hydraulicsupermarket.com/track?p=handp&amp;w=isthsp">you can fix that here, now</a>.<br /> <br /> <br /> *Reference: &quot;No Substitute for Safety&quot;, Hydraulics and Pneumatics Magazine, April 2013; p 56.</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/who-do-you-trust-your-hydraulic-machine#comments Hydraulics At Work Mon, 20 Oct 2014 04:18:00 +0000 29441 at http://hydraulicspneumatics.com October 2014 http://hydraulicspneumatics.com/hydraulics-pneumatics/2014-10-20 <div class="node-body magazine_issue-body"></div> <fieldset class="fieldgroup group-mag-teasers"> <div class="field-mag-teaser"> <a href="/controls-instrumentation/options-add-functionality-motion-controllers">Options Add Functionality to Motion Controllers</a> <a href="/hydraulic-pumps-motors/new-hpu-gives-wwii-sub-new-life">New HPU Gives WWII Sub New Life</a> <a href="/hydraulic-pumps-motors/electrically-powered-gear-pump-slashes-fuel-consumption">Electrically Powered Gear Pump Slashes Fuel Consumption</a> </div> </fieldset> <fieldset class="fieldgroup group-publication-info"><legend>Publication Info</legend> </fieldset> <div class="og_rss_groups"></div> Mon, 20 Oct 2014 04:00:00 +0000 29461 at http://hydraulicspneumatics.com Marmon/Keystone Celebrates Employees’ Focus on Quality Improvement http://hydraulicspneumatics.com/news/marmonkeystone-celebrates-employees-focus-quality-improvement <div class="field-byline"> Alexis Coffey </div> <div class="node-body article-body"><p>Marmon/Keystone recently held its 23<sup>rd</sup> Annual Quality Renewal Celebration to honor employees&rsquo; work in the Quality Improvement Process. The celebration spanned across all 40 Marmon/Keystone locations where each branch spent half the day participating in recreation, team building, and prize giveaways.<img alt="" src="/site-files/hydraulicspneumatics.com/files/uploads/2014/10/QualityCelebration_0.jpg" style="width: 300px; height: 150px; float: right;" title="Quality Improvement Celebration" /></p> <p>Upon hire employees receive training on how the Quality Improvement Process works and then work on one of the Quality Teams where they identify and complete projects that make Marmon/Keystone processes safer, more efficient and cost effective.</p> <p>Thus far, the teams&#39; efforts have resulted in on-time deliveries of 99.63%, returned merchandise at 0.11% and an average of 544 safety pointes per location.&nbsp;</p> <p><em><strong><a href="https://www.marmonkeystone.com/ecomm/servlet/HomepageServlet" target="_blank">Click here</a></strong></em> to learn more about Marmon/Keystone.</p> </div> <div class="og_rss_groups"></div> http://hydraulicspneumatics.com/news/marmonkeystone-celebrates-employees-focus-quality-improvement#comments News Wed, 15 Oct 2014 18:01:00 +0000 29431 at http://hydraulicspneumatics.com