| 摘要 |
PROBLEM TO BE SOLVED: To prevent motion of turning base from moving immediately after finishing the operation of a front attachment. SOLUTION: A brake release cylinder 19 of a turning hydraulic motor 3 are controlled by an opening/closing valve 45, where the valve 45 has a pilot chamber 47 and a pilot chamber 46. In the pilot chamber 47, operating direction selector valves 14, 12a, 12b, 13a, 13b of the front attachment changes the pilot pressure via a control circuit 33. In the pilot chamber 46, a turning operating device 18 changes the pilot pressure via a control circuit 35. In the operation of the front attachment and turning, a brake of the motor 3 is immediately released by the cylinder 19. Upon the completion of the turning operation, the motor 3 is braked, after a throttle 43 stops the motor 3; while/upon the completion of the front attachment operation, the cylinder 19 is made to brake the motor 3, immediately after the operation.
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