Evaluation and Comparison of Alternative Compliant Overrunning Clutch Designs

Abstract

Compliance criteria are used to evaluate the general class of over-running clutches to determine which type is best suited to benefit from compliance. The criteria used in the evaluation include the presence and angle of rotation of revolute joints, the possibility for part count reduction, the presence of springs, possible reduction in weight, and the method of clutch engagement. Sprag, spring, roller or ball, and ratchet and pawl clutch types were evaluated, and the ratchet and pawl type of over-running clutch was demonstrated to be the most promising. Within this type of over-running clutch, different designs incorporating bending, tension, and compression loading of the pawls were explored to determine the best method for loading the pawls. The clutches were compared using the maximum output torque. It was determined that the clutch incorporating rigid pawls loaded in compression produced the largest output torque. The maximum output torque for this clutch was measured at 65.6 N-m.