Patent ID: 7677890

Claim:
A medical or dental handpiece for use with a rotatable tool having a tool shaft for insertion into the handpiece and an axis of rotation, the tool shaft having a torque lock portion of non-circular cross-section having rotational symmetry, the handpiece comprising: a handle portion for gripping by a user; a drive head connected with the handle portion and forming a drive housing; a drive for generating torque, the drive rotatably supported in the drive housing for rotation about an axis of rotation, the drive having an axial bore; and a spindle received in the axial bore of the drive for transferring torque generated by the drive to the rotatable tool when inserted into the handpiece, the spindle having an axial tool bore for receiving the tool shaft, the spindle being connected to the drive for torque transmission, the spindle including a tool retaining arrangement for releasably retaining the tool shaft in the axial tool bore against axial movement upon insertion of the tool shaft into the axial tool bore, the spindle further including a torque lock independent of and axially spaced from the tool retaining arrangement and positioned concentrically in the axial tool bore of the spindle for concentrically receiving the torque lock portion of the tool shaft, the torque lock having at least a portion of non-circular cross-section adapted for engaging and locking at least a portion of the torque lock portion of the tool shaft to prevent rotation of the torque lock portion of the tool shaft in the torque lock, while permitting axial insertion of the torque lock portion of the tool shaft into the torque lock, the torque lock being connected to the spindle for rotation therewith.