| 摘要 |
An operation system for a hoisting device having a hydraulic motor for driving the hoisting device, a clutch mechanism for connecting and disconnecting the motor and the hoisting device cylinder, a foot pedal for applying a brake to the hoisting device by the control of an operator, and an automatic brake mechanism for applying an automatic brake to the hoisting device. The operation system further has first, second and third directional control valves each having a first position and a second position and connected between a hydraulic fluid source and a reservoir and cylinders of the clutch mechanism and automatic brake mechanism to operate such that only when the first and second valves are both in the first position the clutch cylinder is brought into communication with one of the hydraulic fluid source and the reservoir which serves for the clutch disconnection thereby to cause the clutch mechanism to be disconnected and only when the first valve is in the second position and the third valve is in the first position the brake cylinder is brought into communication with the reservoir to cause the automatic brake mechanism to apply the brake, and first, second and third operation devices for operating the first, second and third valves, respectively. The second and third operation devices being operative in response to inoperation and operation of the hydraulic motor in such a manner that when the hydraulic motor is inoperative the second and third valves are in the first position and when the hydraulic motor is operative the second and third valves are in the second position.
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