Belt drive with compression span

1. A toothed belt drive with a compression span comprising:

a first sprocket;

a second sprocket;

a toothed belt having a toothed belt length and trained between the first sprocket and the second sprocket;

a first linear guide member in cooperative relation to and disposed at the predetermined distance (B) from the toothed belt;

a second linear guide member in cooperative relation to and disposed a predetermined distance (B) from the toothed belt; and

the toothed belt length greater than a drive length such that the toothed belt forms a free-standing arcuate span between the first sprocket and the second sprocket on a toothed belt compression span.

2. The belt drive as in claim 1 wherein the difference between the drive length and the toothed belt length is at least ½ times a toothed belt pitch length.

3. The belt drive as in claim 1 wherein the arcuate span is concave with respect to the first linear guide member.

4. The belt drive as in claim 1 wherein the arcuate span is concave with respect to the second linear guide member.

5. A toothed belt drive having a compression span comprising:

a first sprocket;

a second sprocket;

a toothed belt having a toothed belt length, the toothed belt trained between the first sprocket and the second sprocket;

a first linear guide member in cooperative relation to a toothed belt first span;

a second linear guide member in cooperative relation to a toothed belt second span; and

the toothed belt first span having an arcuate concave form when in compression.

6. A toothed belt drive having a compression span comprising:

a first sprocket;

a second sprocket;

a toothed belt having a toothed belt length and trained between the first sprocket and the second sprocket;

a first linear guide member in cooperative relation to the toothed belt and having a predetermined clearance distance (B) from the toothed belt;

a second linear guide member in cooperative relation to the toothed belt and having a predetermined clearance distance (B) from the toothed belt; and

the toothed belt length greater than a drive length by at least one belt pitch length such that the toothed belt forms a compression arcuate span between the first sprocket and the second sprocket.

7. A toothed belt drive comprising:

a driver sprocket;

a driven sprocket having a diameter (D) and separated from the driver sprocket by a distance (S);

a toothed belt trained between the driver sprocket and the driven sprocket;

a first guide member in cooperative relation to the toothed belt;

a second guide member in cooperative relation to the toothed belt; and

the toothed belt comprising a free-standing arcuate belt segment disposed between the driver sprocket and driven sprocket, wherein the arcuate belt segment describes a belt bending radius (R bb ) in the range of S/2≦R bb ≦D/2.

8. The belt drive as in claim 7 , wherein the arcuate belt segment is under axial compression and a second portion of the toothed belt between the driver sprocket and the driven sprocket is under tension.

9. The belt drive as in claim 7 , wherein the toothed belt is in contact with the driven sprocket through an, arc β greater than 180°.

10. The belt drive as in claim 9 , wherein the arc β is in the range of approximately 190° to 250°.

11. A toothed belt drive comprising:

a driver sprocket;

a driven sprocket;

a toothed belt trained between the driver sprocket and the driven sprocket;

the toothed belt comprising a free-standing arcuate belt segment disposed between the driver sprocket and driven sprocket;

a first guide member in cooperative relation to the arcuate belt segment;

the arcuate belt segment is subject to axial compression and a second portion of the toothed belt between the driver sprocket and the driven sprocket is in tension; and

the toothed belt is in contact with the driven sprocket through an arc β greater than 180°.

12. The belt drive as in claim 11 , wherein the arc β is in the range of approximately 190° to 250°.

13. The belt drive as in claim 11 , wherein the first guide member is in spaced relation to the arcuate belt segment.

14. The belt drive as in claim 11 further comprising a second guide member in cooperative spaced relation to the second portion of the toothed belt.

15. The belt drive as in claim 11 , wherein the arcuate belt segment only contacts the driver sprocket and the driven sprocket.