Abstract: A scissor jack of the type which is mountable on and usable in conjunction with a conventional automotive vehicle lift to permit a selected axle of the vehicle to be elevated relative to the lift. The invention provides a gravity activated locking mechanism which includes a plurality of lock keys of different widths. The keys fall individually into a lock position as the jack rises incrementally in height, to prevent unintended lowering of the jack at any height or any time during the lifting process.

Abstract: A wing nut with a threaded axial passage is adapted to engage the threads on the horizontal balancing shaft of a wheel balancer having an abutment thereon. A wheel to be balanced is placed on the shaft and is arranged to be held in tight engagement with the abutment when the wing nut is threaded on the shaft. The surface of the wing nut which forces the wheel against the abutment is recessed with a cylindrical recess. A plastic insert is adapted to be retained within the cylindrical recess and has a central bore which is aligned with the threaded passage in the nut to permit the balancing shaft to pass therethrough. The insert projects axially from the nut body so that the insert, rather than the nut body, will engage the member which is holding the wheel against the abutment.