Patent ID: 6685169
Filing Date: 2004-02-03
Classification: B66F,F16H,Y10S

Abstract:
A lifting unit for a motor-operated jack for vehicles comprising:a spiral lifting ram having a length and a top end and a lower end, said spiral lifting ram having an internal thread formed therein and extending upwardly from said lower end for less than one-half of said length of said spiral lifting ram; a primary screw extending interior of said spiral lifting ram, said primary screw having a horizontal groove formed in a top end of said primary screw; a secondary screw threadedly interposed between said spiral lifting ram and said primary screw, said secondary screw having a pair of longitudinal holes symmetrically formed at a top portion thereof, said secondary screw having an annular groove formed on a top wall thereof; a pin received in said horizontal groove of said primary screw, said pin slightly projecting into said pair of longitudinal holes of said secondary screw; a coil spring; a spring cover; a snap ring, said coil spring and said spring cover and said snap ring being sequentially laid on top of said pin such that said snap ring is seated in said annular groove of said secondary screw, said coil spring biasing said pin such that said secondary screw is prevented from being raised with said spiral lifting ram; and a support ram having a top surface and an external thread, said support ram movably fitted in a gap between said secondary screw and said spiral lifting ram so as to engage another internal thread of said spiral lifting ram at said external thread so as to allow a user to control a moving stroke of the lifting unit.