| 摘要 |
A circuit for driving a hydraulic cylinder (8) of a construction machine includes: a hydraulic pump (10); a tank (T); a control valve (12); a bottom side line (13); a rod side line(14); a quick return circuit (19) having a branch line branched off from the bottom side line and led to the tank and a quick return valve (18) which allows hydraulic fluid to be flowed through the branch line only when the control valve is switched to a contraction driving position; and a recycling circuit (24) which supplies a part of return fluid discharged from a bottom side fluid chamber to a rod side fluid chamber of the hydraulic cylinder. The recycling circuit allows the hydraulic fluid to be flowed only from the bottom side fluid chamber into the rod side fluid chamber of the hydraulic cylinder only when the hydraulic cylinder is switched to the contraction driving position. |
