Abstract: An upright vacuum cleaner having a suction nozzle at the front of the bottom of the chassis is provided with a nozzle height adjusting mechanism for varying the elevation of the rear wheels relative to the chassis to provide a multiplicity of nozzle height positions. The rear axle is journaled on the chassis and includes a pair of off-set legs on which a respective rear wheel is mounted. A wheel bracket is journaled on one end of one off-set crank leg and supports a guide member and a helical end cam track. A follower member having a conjugate helical surface rides on the cam track and supports a locking member on its upper surface. The locking member is secured to the chassis and includes a plurality of detent teeth between each two of which at least one tooth on the follower member is received to lock the follower in a selected position.