Abstract: To provide, for a sliding door with a pneumatically operated door panel servomotor, a safety device which operates independently of the usual reversing device and which limits the maximally active door closing force to an exactly settable value in a simple and reliable manner, there is associated with the servomotor, a limit value control circuit with a closing force sensor which senses the reaction force of the servomotor acting on the door jamb side during the closing process and a sensor-controlled three-position control valve which freely vents the closing pressure side of the servomotor above a given response value of the closing force sensor.