The invention relates to a compressed air motor comprising a housing and a rotor rotatably mounted therein, the rotor being provided with substantially radial slots and plate-like vanes being mounted in the slots so as to be radially displaceable by the centrifugal force, and variable, all-round air chambers being formed between the housing and the outside of the rotor. The vanes are surrounded on the outside by a rotatable sleeve which is provided with at least one passage for the compressed air.