Clutch assembly for electric motors to prevent back drive

A clutch assembly for a motor having a shaft, a worm associated with the shaft and an output gear engaged by the worm, the clutch assembly comprising:

• a clutch body including a central bore there-through and a plurality of pockets in a surface thereof, each pocket having a cam surface defined by a depth of the pocket that gradually increases from a deep end to a shallow end,
• a ball bearing in each of said pockets,
• a spring plate constructed and arranged to maintain the ball bearings preloaded in an associated pocket, the spring plate having an opening therein associated with each ball bearing so that at least a portion of each ball bearing extends through an associated opening, and
• a pressure plate having a portion received in the bore of the clutch body and a flange defining a generally planar surface, the spring plate being disposed between the planar surface and the surface of the clutch body and providing a preload between the clutch body and the pressure plate, the pressure plate being constructed and arranged to be operably coupled with the shaft of the motor,
• the clutch assembly being constructed and arranged such that when the output gear of the motor is driven in a certain direction by an external torque causing an axial force to be exerted on the worm and thus inducing an axial movement and angular movement to the shaft, the flange of the pressure plate comes into contact with the ball bearings, transferring the axial and angular movement to the ball bearings, which in turn move up the cam surface towards the shallow end of each pocket until the ball bearings wedge between the planar surface of the flange and surfaces defining the associated pocket, thereby preventing rotation of the shaft when coupled with the pressure plate.