Check & Load Control Valves

The HYDAC range of direct and pilot operated check valves provide a broad selection of cartridge and inline products with operating pressure rating of up to 6000 psi (420 bar). All valves have a one piece body design and hardened balls or poppets. This provides an excellent product with reliable seating, 2 drops/minute maximum internal leakage, dirt-tolerance and long life.

Check Valves offer optional bias springs and flow capacity up to 44 gpm (165 l/ min). Check valve cartridges fit into Industry standard cavities. A wide selection of cracking pressures are available from 5 to 70 psi (0.35 – 5 bar). Thus they could be used not only as a conventional check but also as a low pressure relief valves.

Pilot Operated Check Valves are available for flows up to 40 gpm (150 l/min) and pilot ratios 3:1 and 4:1. These valves positively lock a load from port 1 to port 2 until pilot pressure applied to port 3 is sufficient to unseat the valve. This flow path provides for higher flow rating in a given cavity, excellent stability and repeatability. They also fit into the same cavity as HYDAC counterbalance valves. These valves provide a low cost alternative to load control when the dynamics of neither overrunning loads nor load release speed are factors to be considered in the design of the hydraulic circuit. They are used for:

• Position load locking.
• As an alternative to counterbalance valves where neither the overrunning loads or release speed are factors in the application.

Single Pilot-to-Open Check Valves and Dual Pilot-to Open Check Valves are inline housed, pilot operated, hydraulic check valves for use as a blocking or load holding device for flow rates up to 20 gpm (80 l/min) and 6000 psi (420 bar). They feature:

• Hardened closing element in a check valve to ensure extended service life and 2 drops/min maximum internal leakage
• Multiple bias spring options for back pressure application flexibility
• Optional sealed pilot piston
• Check section serviceable as a cartridge
• All zinc-plated external cartridge surfaces
• Aluminum or steel inline housings

Counterbalance Valve RS08-01 is a compact cartridge design with operating pressure up to 5000 psi (350 bar) and flow rate up to 10 gpm (38 l/min). These valves are used for

• Precise control of overrunning loads
• Positive load holding in any position
• Protection from pump cavitation
• Thermal expansion relief protection
• Preventing actuators from running ahead of the pump supply

Counterbalance Valves have:

• A built in check valve feature allowing free flow in one direction
• A relief feature controlling flow in the other direction
• A pilot signal that overrides the relief setting providing the counterbalance function