An arrangement of an oil-free compressor apparatus on a rail vehicle for supplying compressed air to pneumatic units assigned to the rail vehicle. The arrangement includes an oil-free compressor and a cooler unit connected with the compressor. The arrangement also includes a rail vehicle having a floor with at least one opening. The compressor is fastened on at least one side to the vehicle floor such that a main axis of rotation of the compressor is arranged essentially vertical with respect to the vehicle floor. The cooler unit interacts with the at least one opening that is configured to take in cooling air to cool the compressor.