| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a hydraulic shovel provided with a regeneration circuit of a cylinder for arm in which operation speed of the cylinder for arm can be reduced sufficiently and an arm can be started slowly in a condition in which a manipulated variable of an operation lever for arm is small and operation speed of the cylinder for arm can be increased sufficiently by increasing the manipulated variable of the operation lever for arm. SOLUTION: A variable restriction 520 is provided in a regeneration circuit 18 which reflexes pressure oil from an oil chamber 6b in a rod side to an oil chamber 6a on a bottom side of a cylinder 6 for arm. Passage area of the variable restriction 20 is controlled in accordance with pilot pressure Pa to a spool valve 14 for arm which is generated by a remote control valve device 10 of an operation lever 9 for arm so that the passage area becomes small when a manipulated variable of the operation lever 9 for arm is small. At the same time, change characteristics of the passage area of the variable restriction 20 can be set to plural kinds of settings by a gain setting switch 28.</p> |
