| 摘要 |
A screw jack (20) includes a stand (21) which houses a side gear (58) which, when rotated, turns a bottom gear assembly (67). An inner screw (73) is connected to the bottom gear assembly (67) and thus turns therewith. Because of an interaction with an outer screw (77), rotation of the inner screw (73) initially causes a tube assembly (24) to move axially relative to a hexagonally shaped sleeve (23). A hex nut (81) is attached to the lower end of the tube assembly (24) to prevent rotation of the tube assembly (24). The nut (81) threadably engages the outer screw (77) and at one stage during the use of the jack (20), the nut (81) also engages a shoulder (82) of the sleeve (23) so that upon continued rotation of the screw (73), the tube assembly (24) and sleeve (23) move axially together. A load bearing assembly (25) is carried at the top of the tube assembly (24) and is adapted to be positioned under the frame or other component of a vehicle to be lifted. When the vehicle is being lifted, the jack (20) is allowed to tilt on selected of feet (48, 49, 50) positioned on the bottom of a base plate (22). The base plate (22) has a plurality of tabs (40) which are folded over edges (37) of a peripheral bottom plate (35) of the stand (21) to attach the base plate (22) to the stand (21). A bearing cup (71) positioned on the base plate (22) receives feet (72) of the bottom gear assembly (67) to floatingly position the bottom gear assembly (67) within the stand (21).
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