| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic circuit of a construction machine which can efficiently prevent the generation of cavitation without causing the lowering of a drive speed of an actuator.SOLUTION: A hydraulic circuit 1 comprises: a drive circuit 4 which drives a hydraulic motor 101 and a hydraulic cylinder 102 by using the hydraulic pressure of a lubricant supplied from a drive pump 3; a control device 7 which controls the supply of the lubricant to the drive circuit 4 by using a pilot pump 71; and a return conduit 5 which returns the lubricant discharged from the drive circuit 4 to an oil tank 2. A makeup circuit 6 for replenishing the lubricant to the drive circuit 4 is connected to the drive circuit 4 independently of the return conduit 5. The makeup circuit 6 comprises a makeup tank 68, and a back-pressure setting valve 64 which sets pressure in the makeup circuit 6 higher than pressure in the return conduit 5. |
