Releasable shaft lock

Claim 1

Releasable means for locking a shaft in an opening in a body, which opening is bounded by a peripheral wall, comprising a plurality of angularly spaced-apart recesses in said wall bounded at least in part by a circumferentially extending ramp-like bottom surface, each recess extending for less than 180* of the wall''s periphery, and a catch surface adjacent to the bottom surface of each recess and extending radially, a peripheral groove in said shaft, a lock member in said groove having a pair of arms embracing the shaft and proportioned so as to be compressed by external forces entirely into the said groove, said lock member being rotatably restrained to the shaft, an ear on each arm projecting radially outward therefrom, said ears constituting the only substantial radial projection of the lock member beyond the radius of the shaft, and each ear having a planar bearing face adapted to bear against the catch surface when the ear projects into a respective recess, a cam surface adapted to bear against and ride along the bottom surface of the recess when the shaft is turned, and a tapered lead-in surface adapted to engage the body when the shaft is pressed into the opening so as to retract the ears and the remainder of the lock member into the peripheral groove, whereby the shaft may be locked to the body by moving the shaft into the opening with the ears aligned with the recesses and be released by turning the shaft to cam the ears out of the recesses so that the bearing faces clear the catch surfaces.