Positive-drive spiral conveyor with overlapping cage-bar caps

1. A spiral conveyor comprising:

a cylindrical drive cage extending from a bottom to a top and having a plurality of parallel cage bars extending in length from the bottom to the top of the drive cage forming a periphery radially outward of an axis of rotation of the drive cage;

a plurality of main cage-bar caps covering a major portion of the lengths of the cage bars,

a plurality of entrance cage-bar caps overlapping a portion of the main cage-bar caps radially outward of the main cage-bar caps and disposed at the bottom or the top of the drive cage.

2. A spiral conveyor as in claim 1 wherein the main cage-bar caps each have an outer surface with a ridge extending parallel to the length of the cage bar and wherein the entrance cage-bar caps each have a slot extending parallel to the length of the cage bar to receive the overlapped ridge on the overlapped portion of the main cage-bar cap.

3. A spiral conveyor as in claim 2 wherein the entrance cage-bar caps each include a ridge aligned with the ridge on the overlapped main cage-bar cap.

4. A spiral conveyor as in claim 1 comprising a plurality of retainers each fastened to a radially interior side on one of the cage bars and to a radially inner side of one of the entrance cage-bar caps to retain the entrance cage-bar cap in place overlapping the main cage-bar cap.

5. A spiral conveyor as in claim 1 wherein the entrance cage-bar caps have ridges defining a first outer radius of the drive cage proximate the bottom or the top and a second outer radius distal from the bottom or the top, wherein the first outer radius is greater than the second outer radius.

6. A spiral conveyor as in claim 5 wherein the entrance cage-bar caps each have an outer surface that tapers radially inward away from the entrance end.

7. A spiral conveyor as in claim 1 wherein the main cage-bar caps are fastened to the cage bars only at a point near the ends of the main cage-bar caps not overlapped by the entrance cage-bar caps.

8. A cage-bar assembly for a spiral conveyor drive cage, comprising:

a cage bar extending in length from a first end to a second end;

a first cage-bar cap covering a majority of the length of the cage bar between the first and second ends;

a second cage-bar cap having an overlapping portion covering a portion of the first cage-bar cap along the length of the cage bar at the first end.

9. A cage-bar assembly as in claim 8 further comprising a retainer fastened to the cage bar and to the second cage-bar cap to retain the second cage-bar cap in place sandwiching the cage bar and the overlapped portion of the first cage-bar cap between the retainer and the second cage-bar cap.

10. A cage-bar assembly as in claim 8 wherein the first cage-bar cap has a ridge extending parallel to the length of the cage bar on an outer side and wherein the second cage-bar cap has a slot extending parallel to the cage bar on an inner side to receive the ridge of the overlapped portion of the first cage-bar cap.

11. A cage-bar assembly as in claim 8 wherein the second cage-bar cap has a ridge that decreases in distance from the cage bar along the length of the cage bar.

12. A cage-bar assembly as in claim 8 wherein the first cage-bar cap is fastened to the cage bar at the second end of the cage bar.

13. A method for constructing a cage bar for a spiral conveyor, comprising:

covering a first length of a cage bar from a first end to a second end with a first cage-bar cap;

overlapping a portion of the first cage-bar cap at the first end of the cage bar with a second cage-bar cap;

fastening the second cage bar cap to the cage bar.

14. The method of claim 13 further comprising fastening the first cage-bar cap to the cage bar only at the second end of the cage bar.