| 摘要 |
A portable lifting jack having a wheeled frame ( 1 ), a lifting arm ( 10 ), a handle ( 11 ) and a hydraulic pump ( 2 ), which includes a multipurpose block ( 20 ) formed as an octogonal column member, and a releasing device ( 40 ) and a piston pump ( 50 ) respectively defined in a rear side of the multipurpose block. A hydraulic actuator ( 60 ) is connected at a threaded hole defined in a front side of the multipurpose block. Two oil chambers ( 24 ) are defined in opposite ends of the multipurpose block and communicate with each other. Particularly, an equalizing valve ( 30 ) is disposed on a top of the multipurpose block and in communication with the oil chamber to equalize the external and internal pressures of the hydraulic pump so as to increase the efficiency of the hydraulic portable lifting jack.
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