Abstract: A belt grinding machine tool with an operating head comprising an endless abrasive belt wound and stretched between at least two spaced rollers arranged parallel one another, of which a first is a driving roller and a second is a tensioning roller being supported to be adjustable in a direction which is substantially perpendicular to its axis of rotation. A device is provided for controlling the position of the abrasive belt which consists of at least a position sensor for sensing the position of the abrasive belt and at least an actuator for adjusting the position of the tensioning roller, in dependence of the position of the abrasive belt being sensed by the position sensor. The position sensor is a fork shaped optical sensor, or an optical sensor having an operatively equivalent shape, and the actuator is an electric drive.

Abstract: A device for quickly replacing a work roll of a machine tool for the surface processing of plate- or strip-like work pieces. The work roll is journaled on suitable journal bearings and the machine tool is provided with roll carrier arms for attachment to the journal bearings. Each of the roll carrier arms comprises a coupling plate and each of the journal bearings comprises a corresponding coupling block for connection to the coupling plate. The coupling plate is provided with a pair of locking pins and the coupling block is provided with a pair of pinholes, for receiving the pair of locking pins when the coupling plate and the coupling block are in a coupling position.