| 摘要 |
A normally engaged wrap spring clutch includes a helical spring which normally is wrapped down on the outer surfaces of aligned input and output hubs to couple the latter. One end of the spring is anchored on the input hub and the other end is secured to a control collar which is telescoped over the spring so that, by turning the control collar relative to the input hub, the spring is unwrapped from the surfaces of the hubs to disengage the clutch. Pins project longitudinally into radial slots in the input hub and spiral slots in the control collar and have substantial mass so that, when the input hub reaches a preselected speed, the pins move radially outward under centrifugal force and, through a camming action in the spiral grooves, turn the control collar relative to the input hub thereby unwrapping the spring. In an alternative embodiment, the outwardly moving pins turn the control collar to cause the spring to wrap down and cause engagement of a normally disengaged clutch.
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