stage gear 156 the first stage gear which provides the first stage of gear reduction is a bevel gear that meshes with a bevel gear 157 integral with the drive shaft 158 of the motor the second stage gear 156 is a straight spur gear that mates with a ball screw gear 159 formed integrally with a ball screw 162 the intermediate cluster gear member is supported by ball bearings 160 and 161 at its ends although reference herein is made to certain structures as being integral as is preferred it should be understood such structures alternatively may be composed of discrete components joined together to form a functionally equivalent structure the ball screw assembly 152 is comprised of the ball screw 162 with the integral gear 159 a hexagonal ball nut 163 that translates rotary motion to linear motion of the ball nut and a pad 164 that attaches to the end of the ball nut and provides the interface to the brake disk pressure plate the ball screw and ball nut which provide a third stage of reduction may be of a known configuration and thus the respective spiral grooves thereof and associated balls have not been illustrated as the same would be immediately.