a lifting jack having a first tubular frame member , a second tubular frame member movably interconnected coaxially with the first frame member , and a selectively operable drive mechanism for moving the second frame member relative to the first frame member . the drive mechanism includes a shaft and a bracket fastened to the second frame member and having two aligned apertures for pivotally mounting a shaft . a protective cover is provided for the drive mechanism and is removably fastened to the shaft .