| 摘要 |
<P>PROBLEM TO BE SOLVED: To achieve favorable operability by restraining a speed change in turn by preferentially supplying a pressurized oil to a swivel motor even if a saturated condition arises when the swivel motor and other actuators are simultaneously operated and by restraining a shock at the start of turn even in a turn-only operation. <P>SOLUTION: A turn control valve 6a is configured by a flow rate control valve 39 that changes an opening area according to a command pilot pressure for turn and an open center type flow rate/direction control valve 40 arranged at the downstream side of the flow rate control valve 39, operated according to the command pilot pressure for turn, and configured to control the flow rate and direction of the pressurized oil supplied to the swivel motor 3a, and the output pressure of an engine speed detection valve 13 is guided to a pressure compensation valve 7a to set a target compensation differential pressure and to other pressure compensation valves 7b, 7c, ..., the target compensation differential pressure is set by the differential pressure between the pump discharge pressure and the maximum load pressure. Shuttle valves 9a, ... that detect the maximum load pressure detect the pressure between the flow rate control valve 39 and the flow rate/direction control valve 40 as a load pressure of the swivel motor 3a. <P>COPYRIGHT: (C)2012,JPO&INPIT |
