Hydraulic Valve Manifolds

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Standing in stark contrast to the mass produced, one-size-fits-most approach of the automobile industry, the equipment in the mobile off-highway sector puts the end-user's work requirements first and foremost, resulting in specialized machines that are custom designed and built for a specific purpose.

Manifolds distribute pressurized hydraulic fluid via valves mounted in them. Tubes return low pressure oil to the manifold where it is consolidated and returned to the reservoir to be be re-circulated through the system. Like the machines themselves, hydraulic valve manifolds are increasingly custom-designed for the application.

Engineers are finding more creative ways to incorporate pumps, cylinders, motors, and the structural part of a power unit into manifolds. "As a result, the market is moving toward custom designs," says Larry Davis, president, Daman Products Co. Inc., Mishawaka, IN. "And with the development of more sophisticated manifold specific design software, we find more complete manifold drawings and more people designing manifolds."

The traditional process for Daman's designers is to work from a customer's bill of materials and hydraulic circuit. "Even though we are often supplied with finished drawings, we put the design through our engineering process," says Davis. "It is our experience that 75% of the construction drawings supplied to us by part-time manifold designers contain a design error, and 50% of all drawings contain an error that would result in field failure. In the spirit of helping our customers be successful, we cannot build from other's designs without testing the integrity of the design."

Over at HydraForce, Lincolnshire, IL, Tony Casale (who will assume the position of vice president-sales and marketing, on Jan. 1) says the first thing that must be decided when developing a manifold is the type of material it is made from. "Material selection is driven by the maximum operating pressure. If the operating pressure is less than 250 bar, then aluminum is the material of choice. If the pressure exceeds 250 bar we would use continuous cast gray iron bar.

"The size of the manifold is dictated by the complexity of the circuit," says Casale. "Obviously, the more complex the circuit, is the larger the manifold will be. The location of the ports and placement of the valves is up to the customer. Every manifold we build is custom for the application and OEM."

For HydraForce, the initial phase of custom manifold design begins with a bill of materials, hydraulic circuit, port sizes and a material recommendation supplied by our distributors.

"Without more information, we will design based on commonly accepted design practices in our industry," says Casale. "A simple one is that all cylinder ports are generally located on the same face for ease of plumbing. After completing the design, we send an approval drawing to which changes can be made if necessary.

"However, our preference is to have more information at the time of quotation. Understanding the application can save time and ensure a streamlined design process. Often there are physical space limitation and specific port locations. This information is used to determine the proper material size and type."

The format of communication used throughout the process is the key to doing a project quickly and correctly. HydraForce's i-Design hydraulic system design software allows engineers to create custom integrated manifolds during the early design stages.

"With i-Design, we design a schematic and give the customer a price for the manifold on the spot," says Casale. "We can mix and match valves such that we can have four different solutions for the same function. The customer can then choose the solution that gives the machine the personality they desire at a known price. From there that same information flows into our design group. If there are any changes or discrepancies, the information flows back to the customer in the same format. The ability to communicate back and forth to the customer with one tool is seamless."