A pneumatic motor having a motor chamber having an inner surface with an eccentric longitudinal axis, a motive gas fluid inlet, and at least one end wall located transversely to the longitudinal axis with an exhaust aperture located therethrough. A rotor is rotatably disposed in the motor chamber on the eccentric longitudinal axis and having a plurality of radial slots, the rotor defining a first rotational position with respect to the longitudinal axis at which the distance between the rotor and the motor chamber is a minimum. A plurality of vanes is slidably carried within the plurality of radial slots and rotationally moving between the fluid inlet and the exhaust aperture during rotation of the rotor. The exhaust aperture is located at a second rotational position with respect to the longitudinal axis such that during rotation of the rotor, the angular distance traveled by each of the plurality of vanes between the first rotational position and the second rotational position in a first rotational direction is greater than 180 degrees.