Tool holding mechanism for a motor driven surgical instrument

摘要

A surgical instrument has a housing which contains a motor that drives a spindle. A tool bit is attached to the motor by a holder that includes a body with a first end portion connected to the spindle, a central portion with a cavity therein, and a second end portion having an aperture through which a shaft of the tool bit passes into the cavity. A pair of lock pawls are pivotally mounted in the cavity with each one having a first tab that enters a slot in the shaft when the lock pawls are in a first position to hold the tool bit in the instrument. The first tabs retract from the slot when the lock pawls are in a second position for changing the tool bit. The lock pawls have second tabs that engage a restrainer only in the second position to prevent the body from rotating. A ring extends around the body and pivots the lock pawls between the first and second positions when the ring moved longitudinally along the body. A manually operable shift lever is pivotally coupled to the housing and move the ring longitudinally along the body.