| 摘要 |
A motor-operated jack for vehicles includes a lifting unit, which includes a spiral lifting ram having an internal thread limitedly formed at a lower portion of the spiral lifting ram, and a pin held in a horizontal groove formed at the top end of a primary screw. This pin is slightly projected into two longitudinal holes symmetrically formed at the top portion of a secondary screw. There is also a coil spring, a spring cover and a snap ring sequentially laid on the top of the pin. There is also a support ram, having a top support and an external thread, movably fitted in a gap between the secondary screw and the spiral lifting ram while engaging with an internal thread of the spiral lifting ram at the external thread, thus allowing a user to control the moving stroke of the lifting unit as desired.
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