HYDRAULIC DRIVE SYSTEM OF CONSTRUCTION EQUIPMENT

摘要

PROBLEM TO BE SOLVED: To provide a hydraulic drive system reducing an energy loss produced when reducing the aperture of a gyration control valve for hydraulic fluid returning to a tank.SOLUTION: A hydraulic drive system 10 of construction equipment comprises: a gyration motor 21; a gyration control valve 40 connected to the gyration motor 21 through a left turn supply line 33 and a right turn supply line 34; and an operation valve 50 outputting a left turn pilot pressure or a right turn pilot pressure to the gyration control valve 40 by receiving gyration operation. The hydraulic drive system also comprises: a first releasing line 71 branched from the right turn supply line 34; a second releasing line 72 branched from the left turn supply line 33; and a releasing device in which during left turn acceleration, the hydraulic fluid is released from the right turn supply line 34 to a tank 23 via the first releasing line 71 while during right turn acceleration, the hydraulic fluid is released from the left turn supply line 33 to the tank 23 via the second releasing line 72.SELECTED DRAWING: Figure 1