Patent ID: 7201547

Claim:
A chuck actuator comprising: a hollow housing having a chamber extending along an axis and having a front end and a rear end and provided with front and rear axial abutments; a ring axially displaceable in the chamber between the abutments, forming with the front end thereof a front compartment, and formed with a bypass passage that is blocked by the rear abutment when the ring bears thereon; a piston in the chamber between the ring and the rear end and forming an intermediate compartment with the ring and a rear compartment with the rear end; an axially extending stem on the piston projecting forward through the ring and through the intermediate and front compartments, adapted to engage and open a chuck and knock a tool from it, and formed with a region of enlarged diameter, the piston being axially shiftable between a rear position with the enlarged-diameter region offset rearward from the ring and with the stem forming with the ring an axially extending passage between the front and intermediate compartments and a front position with the enlarged-diameter portion fitting snugly in the ring and substantially closing the passage; and means including ports opening into the compartments for pressurizing the rear compartment and depressurizing the front and intermediate compartments for shifting the piston forward at a speed slowing when the front position is reached and for pressurizing the front compartment and intermediate compartments and depressurizing the rear compartment for shifting the position rearward into the rear position.