| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydraulic circuit structure for pump switching, which has no occurrence of electric failure at all.SOLUTION: A hydraulic circuit structure for pump switching is for properly switching between a high-speed pump 4 and a low-speed pump 5 when using the high-speed pump 4 and the low-speed pump 5 as a hydraulic pump of a heavy load lifting device using a hydraulic jack 3. The hydraulic circuit structure comprises a high-speed pump hydraulic pressure switching circuit 6 connected to the high-speed pump 4 and a low-speed pump hydraulic pressure switching circuit 7 connected to the low-speed pump 5. The high-speed pump hydraulic pressure switching circuit 6 comprises a first pilot check valve 8 for the high-speed pump and a second pilot check valve 9 for the high-speed pump. The low-speed pump hydraulic pressure switching circuit 7 comprises a first pilot check valve 10 for the low-speed pump and a second pilot check valve 11 for the low-speed pump. |
