Abstract: A stop mechanism for a bending press, plate shear or the like machine, provided with a work-table and with a work-piece stop which is horizontally adjustable along the work table thereby defining the position of the work-piece relative to the machinery, the work-piece stop being coupled with a position control-unit which is provided with an indicator of the momentary position of the work-piece stop and can be programmed with the desired position, the stop being displaceable by means of a hydraulic piston-cylinder unit and a pump drive means controlled by the position control-unit.