Patent ID: 7080719

Claim:
A wrap spring brake comprising: an input source that is alternatively rotated in a first direction, in a second direction and held stationary; a cylindrical sleeve coupled to the input source, the cylndrical sleeve having a mating slot and a notch; a rotatable output shaft; a rotatable spring hub fixed to the output shaft, the spring hub having a dog connection configured to engage the mating slot; a grounding hub through which the output shaft extends; a wrap spring wound over the grounding hub, the wrap spring having a first end and a second end, the first end of the wrap spring coupled to the spring hub and the second end forming a spring toe; and wherein when the input source rotates in the first direction the mating slot engages the dog connection thereby rotating the output shaft in the first direction and causing the wrap spring to overrun the grounding hub, when the input source rotates in the second direction the notch engages the toe of the wrap spring thereby releasing the wrap spring from the grounding hub and the output shaft is caused to rotate in the second direction, and when the input source is stationary the wrap spring is wrapped down on the grounding hub thereby preventing any rotation of the output shaft.