Locking quick-change chuck assembly

A locking chuck assembly for a tool bit shank of the type which has a

• circumferential groove disposed thereabout, the chuck assembly comprising:
• a chuck hub having a forward face and a fixed radial extension;
• a longitudinal bore in the chuck hub for receiving the tool bit shank, the longitudinal bore
• having a terminating face;
• a shuttle disposed in the longitudinal bore, the shuttle having a bit end, a spring end, a
• forward lower face and a rearward interim face and the shuttle being slidable along the longitudinal bore between a rearward position and a forward position;
• a shuttle spring disposed between the spring end of the shuttle and the terminating face of
• the longitudinal bore, wherein the shuttle spring acts to bias the shuttle to its forward position;
• a rear bore extending radially through the chuck hub proximate the terminating face of
• the longitudinal bore so as to be in communication with the longitudinal bore;
• a shuttle detent ball disposed in the rear bore so as to selectively engage the shuttle;
• a front bore extending radially through the hub proximate the forward face of the
• longitudinal bore so as to be in communication with the longitudinal bore;
• a bit detent ball disposed in the front bore so as to selectively engage the circumferential
• groove of the tool bit shank;
• a sleeve disposed annularly about the chuck hub, the sleeve being slidable along the
• chuck hub between a tool bit loaded position and a load/unload position;
• a sleeve spring disposed between the fixed radial extension of the chuck hub and the
• sleeve to bias the sleeve toward its tool bit loaded position;
• wherein when the sleeve is disposed in its tool bit loaded position, the shuttle is
• positioned in its rearward position such that the shuttle spring is compressed and the shuttle detent ball is engaged with the forward lower face on the shuttle so as to prevent the shuttle spring from moving the shuttle, while allowing the sleeve spring to bias the sleeve;
• and
• wherein when the sleeve is disposed in its load/unload position, the shuttle is positioned
• in its forward position such that the shuttle spring is less compressed than when the shuttle is in its rearward position and the shuttle detent ball is engaged with an rearward interim face on the shuttle and the sleeve in a position to allow the shuttle spring to bias the shuttle away from the terminating face of the longitudinal bore.

A method of operating a portion of a chuck assembly of the type having a chuck

• hub which has longitudinally extending bore therein having a closed end and an open end, a radially extending bit ball bore in communication with the longitudinally extending bore, and a bit ball movable in the ball bore between a first retracted position out of the longitudinally extending bore and a second engaged position partially in the longitudinally extending bore, the method comprising the steps of:
• providing a shuttle slidably disposed in the longitudinally extending bore, a compression
• spring for urging the shuttle away from the closed end of the longitudinally extending bore, and a shuttle ball disposed in a radially extending shuttle ball bore in the chuck hub which is in communication with the longitudinally extending bore of the chuck hub;
• and
• moving the shuttle ball in the shuttle ball bore between a first retracted position where the
• shuttle ball contacts a rearward outer section of the shuttle which has a first lateral dimension and a second extended position where the shuttle ball contacts a forward outer section of the shuttle which has a second, smaller lateral dimension so as to limit the extent of forward movement of the shuttle in the longitudinally extending bore.

The method of claim 13, and further comprising the steps of:

• providing a sleeve which is movable longitudinally on the chuck hub between a first
• position and a second position;
• and
• moving the sleeve between (1) the sleeve's first position which in turn causes the bit ball
• to move to its first retracted position and the shuttle ball to move to its first retracted position, and (2) the sleeve's second position which in turn causes the bit ball to move to its second engaged position and the shuttle ball to move to its second retracted position.