Abstract: A sprag clutch includes sprags disposed in a retainer, wherein the retainer includes openings arranged around the retainer, wherein the openings are a first distance from a first annular sidewall of the retainer and are the first distance from a second annular sidewall of the retainer opposite the first annular sidewall; and a first cylindrical surface sharing an edge with the first annular sidewall and extending a second distance from the first annular sidewall, wherein the second distance is less than the first distance; a second cylindrical surface sharing an edge with the second annular sidewall and extending the second distance from the second annular sidewall; and a recessed surface between the first cylindrical surface and the second cylindrical surface.

Abstract: A rotorcraft includes a drive shaft coupled to an engine; a sprag clutch coupled the drive shaft; and an output shaft coupled to the sprag clutch, wherein the sprag clutch physically contacts a first contact surface of the output shaft during operation, wherein a first cross-sectional thickness of the output shaft near the middle of the first contact surface is greater than a second cross-sectional thickness of the output shaft near a first edge of the first contact surface.