rear pane 3 and in schematic representation a control device 4 for operating a front window lifter motor 5 and a rear window lifter motor 6 in this case a front window lift button 7 and a rear window lift button 8 are connected to the control device 4 the front and rear window lifter motors 5 6 are furthermore connected to the control device 4 a rotation speed monitor 9 is connected to the rear window lifter motor 6 and to the control device 4 when the front or rear window lift button 7 8 is actuated the front or rear window lifter motor 5 6 is operated by the control device 4 in this case the front pane 2 or rear pane 3 is moved in accordance with a button command during the movement of the rear pane 3 the rotation speed monitor 9 records the rotation speed n of the rear window lifter motor 6 and the control device 4 analyzes the rotation speed n in order to detect a case of trapping fig2 shows the side part 1 of the motor vehicle with the front pane 2 in the closed state like the front pane 2 the rear pane 3 is in a closed position p 0 in the closed state in the closed position p 0 a front edge 10 of the rear pane 3 adjoins the rear edge 12 of the front pane 2 by means of a fitted sealing lip 11 in this case the front edge 10 and the rear edge 12 are oriented horizontally with respect to the z axis which is based on the typical vehicle coordinate system the adjoining position of the edges 10 12 prevents relative wind and rain.