Counterbalance valve, and control unit and hydraulically powered system comprising the same

摘要

An anti-reaction valve device is configured to open such that a plunger and a sheet member move away from each other in association with first and second set difference pressures. Two anti-reaction valve devices are provided between two pipes fluidically connected to a hydraulically powered actuator such that directional relationship of connection of primary and secondary ports is reversed between the two anti-reaction valve devices so that a reaction of the actuator is inhibited quickly and reliably. A one-way valve means is positioned between the secondary port and an open and close control chamber within which the plunger and the sheet member are movable into contact with and away from each other and serves to inhibit a back flow of a hydraulic fluid. The one-way valve means is capable of inhibiting the plunger and the sheet member from moving away from each other undesirably, and hence malfunction of the anti-reaction valve devices.