Abstract: The invention relates to a combination cylinder, including a service brake cylinder as an active service brake with at least one service brake piston actuated by a pressure medium, the piston actuating a brake mechanism via a service brake piston rod, and further including a spring-loaded brake cylinder as a passive parking brake with a spring-loaded brake piston actuated by a pressure medium against the action of at least one pre-loaded spring, wherein the spring-loaded brake piston in the event of the parking brake is actuated transmits the power of the at least one pre-loaded spring by means of a power-transmitting transmission to the service brake piston rod. According to the invention, the transmission is designed such that the movements of the spring-loaded brake piston and the service brake piston rod are coaxial and the power transmission increases with increasing stroke of the spring-loaded brake piston.