Radial diaphragm spring clutch

1. A clutch comprising:

a stationary sheave, the sheave relatively axially stationary;

a cam directly attached to the stationary sheave;

a movable sheave that is axially movable relative to the stationary sheave along the cam;

a thrust bearing comprising an outer race and an inner race, wherein the outer race is attached to the cam; and

a first radial spring comprising a radially outward annular portion and an radially inward finger portion, wherein the radially outward annular portion is mounted on the movable sheave and wherein the radially inward finger portion bears against the inner race.

2. The clutch of claim 1 wherein the cam comprises a plurality of helical cam slots and the movable sheave is engaged with a plurality of cam followers, each of the cam followers traveling in one of the cam slots.

3. The clutch of claim 2 comprising an odd number of helical cam slots substantially evenly spaced about a periphery of the cam.

4. The clutch of claim 1 wherein the movable sheave further is rotationally movable relative to the stationary sheave along the cam.

5. The clutch of claim 1 further comprising a needle bearing disposed between the outer race and the inner race.

6. The clutch of claim 1 wherein the outer race is fixedly attached to the cam.

7. The clutch of claim 1 further comprising a second radial spring positioned adjacent the first radial spring.

8. The clutch of claim 7 , wherein each of the first and second radial springs comprises a radially inward finger portion, each radially inward finger portion comprising a plurality of fingers and a plurality of spaces between the fingers, wherein the fingers of the first radial spring are rotationally offset from the fingers of the second radial spring.

9. The clutch of claim 8 , wherein a finger of the first radial spring is centered relative to a space of the second radial spring.

10. The clutch of claim 1 further comprising a belt adjuster that permits movement of the stationary sheave relative to the cam.

11. The clutch of claim 10 wherein the belt adjuster comprises a plurality of adjuster pins and a plurality of ramps, wherein each adjuster pin travels along its respective ramp.

12. A clutch comprising:

a stationary sheave, the sheave relatively axially stationary;

a cam attached to the stationary sheave; and

a movable sheave that is axially and rotationally movable relative to the stationary sheave along the cam.

13. The clutch of claim 12 further comprising a radial spring that biases the movable sheave toward the stationary sheave.

14. The clutch of claim 13 wherein the radial spring comprises a radially outward annular portion and a radially inward finger portion, wherein the radially outward annular portion is mounted on the movable sheave.

15. The clutch of claim 14 further comprising a thrust bearing comprising an outer race and an inner race, wherein the outer race is attached to the cam, and wherein the radially inward finger portion bears against the inner race.

16. The clutch of claim 15 further comprising a needle bearing disposed between the outer race and the inner race.

17. The clutch of claim 15 wherein the outer race is fixedly attached to the cam.

18. The clutch of claim 12 wherein the cam comprises a plurality of helical cam slots and the movable sheave is engaged with a plurality of cam followers, each of the cam followers traveling in one of the cam slots.

19. The clutch of claim 18 comprising an odd number of helical cam slots substantially evenly spaced about a periphery of the cam.

20. The clutch of claim 12 further comprising a belt adjuster that permits movement of the stationary sheave relative to the cam.