AUSGLEICHSVENTIL.

摘要

A counterbalance valve provided in a hydraulic circuit to drive a hydraulic motor used for the travel device of a construction machine, and is capable of stopping the hydraulic motor in a short period of time while preventing cavitation and decelerating the motor without shock. Form implementing the above-said function, the valve proper (20) is provided with a spool (26) to allow ports (22, 23) on the sides of first and second pumps to communicate with or to be cut off from other ports (24, 25) on the sides of first and second motors, respectively. A structure provided is such that the spool is held in the neutral position with the spring force, displaced to the first position at which the port (23) on the side of the second pump communicates with the port (25) on the side of the second motor by pressure oil in the pressure receiving chamber (28) on the left side, and displaced to the second position at which the port (22) on the side of the first pump communicates with the port (24) on the side of the first motor by pressure oil in the pressure receiving chamber (29) on the right side, in which a plurality of throttle holes (37, 38 and 39) are formed between the pressure receiving chamber (28) on the left side and the port (22) on the side of the first pump as well as between the pressure receiving chamber (29) on the right side and the port (23) on the second pump so as to allow these ports to communicate with each other. An area produced by the throttle holes communicating with each other is maximum when the spool is in the first and second positions, minimum when the spool is slightly displaced toward the neutral position, and medium between the both when the spool is displaced further toward the neutral position.