US Patent 7255546 Spindle for a vane motor

The spindle of a vane motor is designed to enhance the power, speed and torque by undercutting the spindle adjacent to the vanes on the power stroke side to increase the working area of the vanes and by adding slots intermediate the vane formed in said spindle and each slot has a working face for accepting pressurized air during the power stroke. The slots are located out of coincidence with the rotating axis of the spindle and the vanes include a contoured bottom edge fitted into the slots so as to enhance its ability to be retracted in opposition to centrifugal force created by the rotating cylinder.