Automatic tool-bit holder

1. In a tool-bit holder of the type having a hub, wherein the hub has a longitudinally extending axial bore for receiving a tool-bit therein, a detent ball radially projecting into the bore to selectively engage the tool-bit, and a circumferential ramp that is longitudinally moveable over the detent ball to cause radial movement thereof, wherein the tool-bit holder has a distal end for receiving the tool-bit therein and a proximal end, the improvement which comprises:

a longitudinally moveable member that extends through a slot in the hub and radially into the bore, wherein the circumferential ramp is moveable as a function of longitudinal movement of the moveable member relative to the hub;

an inner ring disposed about the hub in coupled engagement with the moveable member, wherein the inner ring is longitudinally moveable relative to the circumferential ramp;

an inner ring spring biasing the inner ring distally toward the circumferential ramp; and

a sleeve spring biasing the circumferential ramp distally relative to the hub.

2. The improvement of claim 1 wherein the moveable member is a ball.

3. The improvement of claim 1 wherein the moveable member is a pin.

4. The improvement of claim 1 wherein the inner ring spring and sleeve spring are concentrically disposed about the hub.

5. The improvement of claim 1 wherein the tool-bit holder has a distal end for receiving the tool-bit therein and a proximal end, and further comprising:

a sleeve spring biasing the circumferential ramp proximally relative to the hub.

6. The improvement of claim 1 wherein the hub has a plurality of the slots therethrough, and wherein a plurality of the moveable members are provided, wherein each moveable member extends radially into the bore through a respective one of the slots.

7. The improvement of claim 1 wherein the tool-bit has a radially outwardly extending edge between portions thereof, and wherein the moveable member extends into the bore only to an extent sufficient to be engaged by the radially extending edge of the tool-bit.

8. The improvement of claim 7 wherein the radially outwardly extending edge comprises one or more end faces of corners of a hex-shaped shank portion of the tool-bit.

9. In a tool-bit holder of the type having a hub, wherein the hub has a longitudinally extending axial bore for receiving a tool-bit therein, a detent ball radially projecting into the bore to selectively engage the tool-bit, and a circumferential ramp that is longitudinally moveable over the detent ball to cause radial movement thereof, wherein the tool-bit holder has a distal end for receiving the tool-bit therein and a proximal end, the improvement which comprises:

a longitudinally moveable member that extends radially into the bore only to an extent sufficient to be engaged by a radially outwardly extending edge between portions of the tool-bit when the tool-bit is inserted in the bore, wherein the circumferential ramp is moveable as a function of longitudinal movement of the moveable member relative to the hub;

an inner ring disposed about the hub in coupled engagement with the moveable member, wherein the inner ring is longitudinally moveable relative to the circumferential ramp;

an inner ring spring biasing the inner ring distally toward the circumferential ramp; and

a sleeve spring biasing the circumferential ramp distally relative to the hub.

10. The improvement of claim 9 wherein the moveable member is a ball.

11. The improvement of claim 9 wherein the moveable member is a pin.

12. The improvement of claim 9 wherein the inner ring spring and sleeve spring are concentrically disposed about the hub.

13. The improvement of claim 9 wherein the tool-bit holder has a distal end for receiving the tool-bit therein and a proximal end, and further comprising:

a sleeve spring biasing the circumferential ramp proximally relative to the hub.

14. The improvement of claim 9 wherein a plurality of the moveable members are provided.

15. The improvement of claim 9 wherein the radially outwardly extending edge comprises one or more end faces of corners of a hex-shaped shank portion of the tool-bit.

16. A tool-bit holder comprising:

a hub for receiving a tool-bit within an axial bore thereof;

a sleeve longitudinally moveable along the hub;

an inner ring within the sleeve, wherein the inner ring is longitudinally moveable relative to the sleeve and relative to the hub;

at least one detent disposed between the sleeve and the hub and adapted to radially engage the tool-bit;

a moveable member extending radially into the bore through a longitudinal slot in the hub, wherein proximal movement of the moveable member relative to the hub causes proximal movement of the inner ring;

an inner ring spring biasing apart the inner ring and a spring abutment surface of the hub; and

a sleeve spring biasing apart the inner ring and a spring abutment surface of the sleeve wherein, upon insertion of the tool-bit into the bore to engage the moveable member, the inner ring, inner ring spring, sleeve spring and sleeve cooperate to urge the detent against the tool-bit.

17. The tool-bit holder of claim 16 wherein the moveable member extends partially into the bore of the hub.

18. The tool-bit holder of claim 17 wherein the moveable member is a ball.

19. The tool-bit holder of claim 17 wherein the moveable member is a plurality of balls.

20. The tool-bit holder of claim 17 wherein the moveable member is a pin.

21. The tool-bit holder of claim 17 wherein the moveable member is a plurality of pins.

22. The tool-bit holder of claim 16 wherein the moveable member extends completely across the bore of the hub.

23. The tool-bit holder of claim 16 , and further comprising:

an annular member disposed on the sleeve, wherein engagement with the annular member urges the detent radially inwardly.

24. The tool-bit holder of claim 16 wherein the sleeve is rotatable about the hub.