Compressed-air supply system for operating a pneumatic installation, said system in particular having a reservoir or similar pressure-air reservoir and a number of bellows or similar pressure-air chambers, the supply system having: - a pressure-air feed, to which a charging assembly having a compressor is connected on the pressure-medium feed side, - a pressure-air connection to the pneumatic installation and a venting connection to the environment, - a pneumatic main line between the pressure-air feed and the pressure-air connection, and - a vent line between the pressure-air feed and the venting connection characterized in that - a changeover valve is associated with the pressure-air feed, wherein - the changeover valve is designed to be controlled by pressure air in such a way that the pressure-air feed is open or can be opened via the changeover valve to the main line, and, - by means of a flow pressure (p) at the pressure-air feed that can be generated by the charging assembly to the main line, - in the unpressurized state of the pressure-air feed, the pressure-air connection is connected to the vent line in terms of flow, and - in the pressurized state of the pressure-air feed, the pressure-air connection is not connected to the vent line in terms of flow, wherein the changeover valve is arranged on the pressure-air feed while connecting a first part (60.1) of the pneumatic main line to a pressure control connection and connecting a second part (60.2) of the pneumatic main line to a pass-through connection and connecting the vent line to an outlet connection and wherein the changeover valve is designed to be controlled by pressure air in such a way that it is switched over in accordance with a pressure (p) applied to the pressure control connection and/or in accordance with a volume flow of pressure air flowing from the pressure control connection into the pneumatic main line. - a pressure-air feed, to which a charging assembly having a compressor is connected on the pressure-medium feed side, - a pressure-air connection to the pneumatic installation and a venting connection to the environment, - a pneumatic main line between the pressure-air feed and the pressure-air connection, and - a vent line between the pressure-air feed and the venting connection characterized in that - a changeover valve is associated with the pressure-air feed, wherein - the changeover valve is designed to be controlled by pressure air in such a way that the pressure-air feed is open or can be opened via the changeover valve to the main line, and, - by means of a flow pressure (p) at the pressure-air feed that can be generated by the charging assembly to the main line, - in the unpressurized state of the pressure-air feed, the pressure-air connection is connected to the vent line in terms of flow, and - in the pressurized state of the pressure-air feed, the pressure-air connection is not connected to the vent line in terms of flow, wherein the changeover valve is arranged on the pressure-air feed while connecting a first part (60.1) of the pneumatic main line to a pressure control connection and connecting a second part (60.2) of the pneumatic main line to a pass-through connection and connecting the vent line to an outlet connection and wherein the changeover valve is designed to be controlled by pressure air in such a way that it is switched over in accordance with a pressure (p) applied to the pressure control connection and/or in accordance with a volume flow of pressure air flowing from the pressure control connection into the pneumatic main line.