How to go modular
With these advantages available, it’s easy to understand why hydraulic integrated circuits have steadily grown in popularity. However, many traditional line-mounted, and transitional subplate/manifold systems are still in use, so managing the transition to a modular system is critical to its success.
A circuit designer’s first impulse often is simply to duplicate an existing traditional system as a modular one. If the original circuit consists only of simple check and relief valves, this approach may suffice. But if you are updating a line-mounted system and enhancing its performance with electrohydraulic proportional valves or load-sensing priority flow regulators, the do-it-yourself approach will likely be a mistake. Much more is involved in making this kind of change than simply substituting new components for the old ones.
For example, the shorter, more efficient flow paths of the hydraulic integrated circuit will inevitably alter the response and performance of other system components. Sometimes the changes are subtle, and sometimes they are not, but either way, they must be anticipated and accounted for.
Internal flow paths also impact performance. If you place a pressure port so it restricts flow to a flow divider, the result may be an underperforming device. The relative locations in a line-mounted system might not be as critical, or may simply be masked by other losses. But the very process of making the hydraulic integrated circuit more compact can sometimes magnify the impact of even the smallest details.
There’s nothing like experience
The answer to these, and many other potential pitfalls, is to work with an experienced engineering team thoroughly familiar with the intricacies of hydraulic integrated circuits. Yes, you could do it yourself, but the odds are you will get a better result by letting an expert handle the task.
Even then, some guidelines will help ensure a successful outcome. Perhaps the most important of these is to have realistic expectations about what can be achieved with an integrated circuit.
• A sophisticated, multi-function, high-pressure, high-flow system is not going to work if the specifications call for it to be crammed into a shoebox-sized block of aluminum.
• Ten or 15 valves won’t fit in that shoebox, no matter how clever the designer.
• A 1-in. port requires a certain amount of material, and the equivalent performance can’t be achieved with a …-in. passage, no matter how convenient that would be.
• A valve that needs to be “burped” at machine startup must be on top of the manifold block, period.
• If the system will operate at 5000 psi, the manifold block must be steel, regardless of how light you would like it to be.
This all may seem obvious, but every engineer who works with hydraulic integrated circuits can recount real-life instances of each of those examples, and many others as well. The best advice in this regard is to talk to the application engineer and designer early in the development of your hydraulic system.
Eaton and other suppliers have teams of application and product engineers and hydraulic integrated circuit designers dedicated to providing comprehensive support over the life of the application. The more often a supplier team deals with the intricacies of integrated system design, the more likely they are to produce an efficient solution to your requirements.
What they absolutely need to know is how the machine will be used, and what kind of environmental conditions to expect. There is a world of difference between mounting a manifold in the cab of a logging vehicle where it may well be underwater occasionally, and attaching it to a precision machine tool working in an air-conditioned shop. Both may be excellent candidates for a hydraulic integrated circuit, but the systems themselves will be very different.
The more accurately you can define what the system is expected to do, and what the machine it is controlling is expected to do, the more likely you are to achieve a successful result. Hundreds of decisions must go into a successful integrated circuit, and there is no substitute for getting an experienced engineering team involved early in the project. Give them the information they need and let them do what they do best. You will like the result.
Manual lever valves simplify manifold blocks
The latest addition to Eaton’s Vickers screw-in cartridge valves includes the MLV9 manual lever valve, for mobile and stationary applications at pressures to 210 bar. They integrate into custom manifold blocks or manifold circuit designs (MCDs), which combine many cartridge valves into a common manifold block.
When used independently or in a hydraulic integrated circuit, they offer fewer potential leakage points than line mounted valves for clean, safe environments; save weight and space; and act as efficient, low-maintenance systems with high productivity.
They replace pull- and push-to-shift, 3-position, 4-port, tandem center, mobile sectional, and manually-operated industrial manual valves and come in open center, closed center, tandem pool, and motor spool configurations. An open center in the motor spool permits a motor to freewheel when the valve is centered, rather than being brought to a stop. Motor spools provide directional control of free-moving cylinders when not being extended or retracted.
Screw-in valves for harsh environments
In addition to MLV9 cartridge valves, Eaton offers more than 30 Vickers screw-in cartridge valves for stationary and on- or off-highway equipment. They accommodate pressures to 350 bar and flows to 150 lpm and come in direct acting, proportional and solenoid, flow control, pressure control, and directional control models supported by many logic elements. They are NFPA rated and have an environmental standard rating of 1P69K. Sizes and materials include 18 proportional valves in sizes 8, 10, and 12; 11 valves in the size 12 range; and extended stainless steel range.
Click here for more informaiton on cartridge valves from Eaton Hydraulics.