Autolocking hammer-drill chuck

In combination with

• a hammer drill having a drive spindle rotatable about a spindle axis and a hammer displaceable axially in the drive spindle,
• a drill bit having a shank extending along a shank axis and having a radially outwardly open and at least generally axially extending groove, and
• a chuck key having a centering tip and a gear crown therearound,
• a chuck comprising:
• a generally tubular chuck body centered on a chuck axis and having a central axially extending passage and a radially outwardly open centering hole, the body normally being carried on the spindle and receiving the shank of the drill bit in its passage with the spindle, shank, and chuck axes all coaxial, the hammer projecting axially forward into the passage and being engageable therein with the bit;
• a plurality of jaws radially but not angularly displaceable in the chuck body and having inner ends engageable with the drill-bit shank in the passage;
• formations angularly nondisplaceable on the chuck body and complementarily engageable in the groove of the drill-bit shank, whereby the formations can angularly couple the chuck body and drill bit;
• means including an adjustment ring connected to the jaws for moving same radially synchronously and thereby centering the bit in the body by engagement of the inner ends with the shank, the ring being formed with axially backwardly directed teeth positioned axially forward of the centering hole such that when the chuck key is fitted into the centering hole its crown gear meshes with the ring teeth;
• a locking sleeve axially but not angularly displaceable on the body and carrying at least one tooth axially engageable between the ring teeth, the sleeve being axially displaceable on the body between an axially forward locking position with the sleeve tooth engaged with the ring teeth and the sleeve positioned relative to the hole such that the key cannot be fitted to the chuck with the gear meshing with the ring teeth and an axially backward freeing position with the sleeve tooth out of engagement with the ring teeth and the sleeve positioned relative to the hole such that the key can be fitted to the chuck with the gear meshing with the ring teeth;
• and
• biasing means braced between the sleeve and the body for urging the sleeve axially forward into the locking position.