| 摘要 |
<p>A hydraulic circuit for a hydraulic-operated crane, which comprises a manually-operated changeover valve center-bypassed at a neutral position for switching the hydraulic oil from a pump to thereby operate the actuator of the crane, a solenoid valve connected to the return hydraulic circuit of the hydraulic circuit for switching the hydraulic oil to the actuator of the crane to be remotely operated and connected in parallel with the manually-operated changeover valve, said solenoid valve being also connected at the output port to the actuator of the crane, and a proportional solenoid relief valve connected in parallel with the solenoid valve. Thus, the hydraulic crane can be manually directly or remotely independently operated. When both the manual and remote operations are simultaneously executed, the crane can be precisely operated in a superinching manner. The crane can be simply stopped in emergency in both the manual and remote operations. </p> |
