Patent ID: 8800402

Claim:
A motor mechanism comprising: a threaded member interconnected to a motor and rotatable in both a clockwise and counterclockwise direction; a split nut mounted on the threaded member, the split nut comprising at least two members, at least one of which has an inner threaded surface which complements the threads on the threaded member; at least one resilient member interconnected to the split nut and applying a force causing the threaded surface of the at least one member to engage the threads of the threaded member when the threaded member is rotating in the clockwise and when the threaded member is rotating in the counterclockwise direction; a first physical stop limiting movement of the split nut along the threaded member in one direction and a second physical stop limiting movement of the split nut along the threaded member in the opposite direction; wherein, when movement of the split nut along the threaded member is stopped while the threaded member continues to rotate in the clockwise direction, the inner threaded surface of the at least one member will disengage and reengage the threads of the threaded member, and when movement of the split nut along the threaded member is stopped while the threaded member continues to rotate in the counterclockwise direction, the inner threaded surface of the at least one member will disengage and reengage the threads of the threaded member.