| 摘要 |
A jack (11) is provided with a thumb wheel (10) preferably made of a plastic material. The jack (11) includes a side gear having an end (20) extending out of a side gear housing (18). The housing (18) has an outer peripheral lip (19) which is engaged by the thumb wheel (10). The thumb wheel (10) includes a plate (24) having an aperture (26) therein of a configuration complementary to that of the side gear end (20) so that when the thumb wheel (10) is positioned on the jack (11), the side gear end (20) will be within the aperture (26) and will rotate upon rotation of the plate (24). The thumb wheel (10) also includes a collar (30) having a plurality of slots (33) therein and a circumferential barb (31) near the end thereof. Upon installing the thumb wheel (10), the collar (30) flexes and the barb (31) snaps over and engages the lip (19) on the housing (18). The engagement is only in the axial direction such that the thumb wheel (10) will freely rotate with respect to the housing (18).
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