Abstract: This invention relates to an underfloor wheel set lathe for the profiling of wheel sets of trackbound vehicles of the type in which the wheels are at least in part supposed by rolls carried by a roll carrier, at least one of the rolls being driven. Movement of the roll carrier is resisted by a horizontally acting brake mechanism which permits vertical lifting movements of the carrier. The force with which horizontal movement is resisted may, by suitable hydraulic means, be controlled as a function of the cutting force or driving force imparted to the wheels, the lifting force exerted against the wheels, or otherwise coordinated with the force applied in the course of profiling.

Abstract: Track wheels such as railroad wheels are trued or reprofiled by first turning or cutting over only a portion of the tread surface width of each wheel of a set, whereby the cutting depth for this initial turning is smaller than the cutting depth required for the truing. The diameters of the initially turned portions of both wheels of a set are then compared to provide a difference value. The lower diameter wheel is then turned in accordance with the respective lower diameter value. The higher diameter wheel, if any, is also turned in accordance with the lower diameter value plus in accordance with one half of said difference value.