| 摘要 |
<p>PURPOSE:To take out the working oil independently of the operation of a hydraulic device for raising/lowering a working machine by installing a means for locking an unload valve which is unloaded in the operation of the hydraulic device, in an unloaded state, in free release state onto the unload valve. CONSTITUTION:The discharge oil passages 9 and 10 for the first and second hydraulic pumps 7 and 8 are connected to a convergence flow oil passage 12, and a control valve 2 for a hydraulic device 1 for raising/lowering a working machine which is connected with the convergence flow oil passage 12 and auxiliary control valves 5 and 6 for assisting working machine are interposed between the hydraulic pumps 7 and 8. Further, an unload valve 13 which is unloaded in the operation of the hydraulic device 1 is connected in the discharge circuit 10 of the second hydraulic pump 8. Further, on the hydraulic pump 7, 8 side in comparison with the auxiliary control valve 5, 6 in the convergence flow oil passage 12, a hydraulic pressure taking-out part 27 is arranged. In this constitution, a locking means 20 for locking the unload valve 13 in an unloaded state is installed in free release manners onto the unload valve 13.</p> |
