Overcenter valves are used where there is vital importance in the system. VBCD DE series are used to control actuator’s movement and block in both directions. Pressure is adjustable and sensitive. They can be used on crane booms.
液压双向平衡阀在液压系统中起着重要作用，VBCD DE系列双向平衡阀被用于控制执行器的移动和锁住执行器的动作。
DOUBLE OVERCENTER VALVE 双向平衡阀
Overcenter valves have great importance in hydraulic systems and have following features:
平衡阀在液压系统中起着重要作用，有以下功能。
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.
负载保持：当电池换向阀在中位时，液压平衡阀可以防止负载下降。
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.
控制负载下降速度：液压平衡阀阻止油缸或者马达过速运动。
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.
负载安全：在油管爆管的情况下，液压平衡阀阻止负载不受控制的运动。
These valves are used where there is vital importance in the system.
VBCD DE series overcenter valves are used to control actuator’s movement and block in both directions. Pressure is adjustable and sensitive. They can be used on crane booms. Standard pressure setting is 320 bar.
Description
It provides static and dynamic control of load by regulating the flow IN and OUT of the actuator, through ports C1 and C2. This valve module includes 2 sections, each one composed by a check and a relief valve pilot assisted by pressure in the opposite line: the check section allows free flow into the actuator, then holds the load against reverse movement; with pilot pressure applied at the line across, the pressure setting of the relief is reduced in proportion to the stated ratio until opening and allowing controlled reverse flow. Back-pressure at V1 or V2 is additive to the pressure setting in all functions.
它通过调整进回油的流量实现对油缸的动态、稳定控制。平衡阀包含两个部分（单向阀和溢流阀），每一侧都包含一个单向阀和先导溢流阀（先导油的压力由对侧提供）。单向阀部分允许油液进入油缸并阻止反向流通；同时向对侧提供先导压力油，随着先导油压力增大，根据固定的先导比从而影响溢流阀的阀芯开度，直到允许油液流出且时刻控制油液。
