Bumper screw jack

A lifting jack comprising:

• an upstanding hollow strut member having a longitudinal opening along one side, a screw rod rotatably disposed in said strut member, support means at the upper end of the strut member and screw rod for supporting the screw rod in the strut member, the support means including a cap secured to the top of the strut member and having a flat top, first and second flat disk members directly atop the cap each having flat bearing surfaces and a washer element directly atop the flat disk member, the washer element including a flat bearing surface for engaging a disk and a noncircular recess at least partly defined by bevelled bottom surfaces, the screw rod being formed with shoulder portions bevelled to fit into the washer element noncircular recess and mate with the recess bottom surfaces so as to cause the washer element to rotate in unison with the screw rod, the support means thereby providing a first planar frictional bearing interengagement plane between the directly and abuttively interengaging washer element and the first flat disk, a second planar frictional bearing interengagement plane between the directly and abuttively interengaging first flat disk and second flat disk, and a third planar frictional bearing interengagement plane between the directly and abuttively interengaging second flat disk and flat cap top, the lifting jack further including load-lifting means interconnected with the screw rod for movement longitudinally of the screw rod upon screw rod rotation, the load lifting means including spaced apart side wall members on opposite sides of and exterior to the strut member, and unitary planar glide members each fixed in the load lifting means between mounting slots in the side wall members and having enlarged portions extending between the side wall members to slidably bear against the upstanding strut member and encourage easy motion of the load lifting means up and down the strut member.