design of hydraulic systems

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OVERCENTER valves

valvole overcentre general fluidi

Overcenter valves are the key to hydraulic control and are used mainly for the following purposes:


Load holding: The overcenter valve prevents the movement of a load when the directional valve is in the neutral position, permitting the use of open center directional valves and negating leakage past the spool of closed center directional valves.

Load control: The overcenter valve prevents the actuator running ahead of the pump due to the load-induced energy, thereby eliminating cavitation in the actuator and loss of control.

Load safety: In the case of hose failure, an overcenter valve mounted onto or into a cylinder will prevent uncontrolled movement of the load. When a cylinder is used in a boom, as in a crane, then hose failure protection is vital as the loss of load control could cause damage to people or property.