Collet assembly

In a collet assembly, a housing affording an internal collet nest, a collet actuator sleeve member positioned inside the nest and presenting an internal taper for receiving an external taper on the split end of the collet, said sleeve member being guided for outward actuating movement relative to the housing to present the narrower part of said internal bore to the split end of the collet to apply a circumferential contracting force thereto, a rotatable actuator disc in the nest supporting a plurality of balls engaged with the inner end of the sleeve member, a first wear ring member, engaged with the balls, located in the nest on the side of the actuator disc opposite the sleeve member, one of said members having seats in which the balls normally repose in a retracted position of the sleeve member such that on rotating said actuator the balls are unseated to actuate the sleeve member outward, a spring washer in the nest engaged with said wear ring member normally to urge the balls into their seats, and a second wear ring member engaged with said spring washer on the side thereof opposite the first wear ring member.