Patent ID: 7448870

Claim:
A handpiece for dental or surgical use, including: a hollow shaft rotating around a longitudinal axis and mounted via bearings in a fixed tubular shaft, a collet mounted in a front end of the hollow shaft and having a central channel for receiving the shank of a removable tool, the collet including axial arms distributed around the axis and each provided with a jaw in the central channel, a gripping mechanism carried by the hollow shaft and arranged for exerting a centripetal force on a support surface of each arm of the collet to grip the tool shank between the jaws of the collet, and a releasing mechanism carried at least in part by a the fixed tubular shaft and arranged for acting on the gripping mechanism at least so as to release the collet, wherein the gripping mechanism includes a sliding sleeve mounted on the hollow shaft and, for each arm of the collet, a transmission element arranged in a radial hole of the hollow shaft between said support surface of the arm and an inner cam surface of the sliding sleeve, and wherein the releasing mechanism includes a sliding collar arranged in the fixed tubular shaft and actuated by a manual control member such that the latter can move the sliding collar axially to drive the sliding sleeve of the gripping mechanism so as to release the collet, and wherein said cam surface includes a first hollow provided with said inclined surface and also a second hollow that is shallower than the first and separated therefrom by a projecting part and wherein the arms of the collet are resilient, such that the second hollows form a notch which holds the sliding sleeve in place when said transmission elements are engaged in the second hollows by the resilience of the collet arms.