A compressed air supply device for a rail vehicle, having a main compressor for generating compressed air for a pneumatic brake system and a vehicle battery for supplying electric energy. The compressed air generator for supplying additional auxiliary air for operating at least one pneumatic actuator is provided in a frame of an adjusting drive for a pantograph. The compressed air generator for supplying auxiliary air includes an electric frequency converter for operating the electric-motor driven main compressor of the rail vehicle with low rotational speed from the electric drive energy provided by the vehicle battery. A secondary line is attached to the compressed air line connected to the main compressor to branch off the auxiliary air for the supply of auxiliary air of the actuator.