Hydraulic drive system

摘要

PCT No. PCT/JP93/00677 Sec. 371 Date Dec. 14, 1993 Sec. 102(e) Date Dec. 14, 1993 PCT Filed May 21, 1993 PCT Pub. No. WO93/24757 PCT Pub. Date Dec. 9, 1993.A hydraulic drive system comprises a check valve cb1 for detecting a pressure on the outlet side of a pressure compensating device VB1, a maximum load pressure detecting line SL1 for selecting higher one of the pressure detected by the check valve cb1 and a load pressure of an actuator associated with a hydraulic pump P1 and supplying it as a signal pressure, a check valve cb2 for detecting a pressure on the outlet side of a pressure compensating device VB2, a maximum load pressure detecting line SL2 for selecting higher one of the pressure detected by the check valve cb2 and a load pressure of an actuator associated with a hydraulic pump P2 and supplying it as a signal pressure independently of the maximum load pressure detecting line SL1, and a passage 300 for joining hydraulic fluids supplied from the hydraulic pumps P1, P2 and passing through variable restrictors RB1, RB2 with each other and supplying it to an actuator B. Mutual independence between the two hydraulic pumps P1, P2 can be thereby ensured.