Self-tightening drill chuck

A drill chuck comprising:

• a chuck body centered on and rotatable about an axis;
• a holder body rotatable on the chuck body and formed with a plurality of angularly spaced guides;
• a front sleeve surrounding the bodies;
• respective jaws in the guides between the front sleeve and the chuck body;
• means for shifting the jaws in the guides forward and together on rotation of the holder body in a tightening direction relative to the chuck body and for opposite shifting of the jaws on rotation of the holder body relative to the chuck body in an opposite loosening direction;
• an annular array of teeth rotationally fixed to one of the bodies;
• a pawl angularly fixed on the other of the bodies and engageable with the teeth;
• a spring biasing the pawl into engagement with the teeth, the pawl and the array of teeth being oriented such that when the pawl is in a locking position engaged with the array of teeth the holder body can rotate relative to the chuck body in the tightening direction but not in the loosening direction and when in a freeing position disengaged from the teeth the holder body can rotate freely in either direction relative to the chuck body;
• respective interengaging stops fixed rotationally to the other body and to the front sleeve and limiting relative angular movement of the front sleeve on the other body between a pair of angularly offset end positions;
• a back sleeve fixed rotationally in the front sleeve;
• a cam formation engageable with the pawl in only one of the end positions, fixed rotationally to the sleeves, and holding the pawl when engaged therewith in the freeing position, the pawl being biased by the spring in the other end position into the locking position, the back sleeve having an end rim forming one of the stops;
• and a spring-loaded retainer carried on the back sleeve and held by the end rim thereof, having a pair of angularly offset seats engageable with the front sleeve, and releasably holding the front sleeve relative to the other body in the end positions.