| 摘要 |
A driving member (15) of piston type has an upper side, on which an annular holder (28), upper and lower cams (31),(32), and a transmission sleeve (33) are arranged in order. An annular wedge space (35) is defined between the upper and lower cams (31) and (32). A plurality of wedging members (36) are inserted into the wedge space (35) as peripherally spaced apart at a predetermined distance. When the driving member (15) is driven upward, first a plurality of engaging balls (41) supported by the transmission sleeve (33) engage with a lower portion of a pull rod (12) and then a pushing surface (38) of the driving member (15) vertically separates the cams (31),(32) from each other through the wedging members (36). Thus the lower cam (32) drives the pull rod (12) downward through the transmission sleeve (33) and the engaging balls (41). <IMAGE> |
