Conveyor drive

Abstract

A sprocket drive assembly designed for a modular chain link conveyor belt subject to relatively large variations in width due to changing ambient conditions such as large cyclic temperature changes. The assembly includes a drive shaft with a square cross section and a plurality of sprockets mounted on the shaft for rotation thereby. One sprocket is fixed against axial movement to provide for proper belt tracking while the remaining sprockets, the number depending upon the width of the belt and the load carried thereby, are located on opposite sides of the fixed sprocket and are free to move axially to accommodate for changes in belt width.

What is claimed is: 
     
       1. A sprocket and drive shaft assembly for a chain link conveyor belt subject to variations in width comprising, in combination: a drive shaft with a substantially uniform, noncircular cross section; and   a plurality of sprockets mounted in driven engagement on said shaft for supporting and driving a conveyor belt; one of said sprockets being releasably locked against axial motion to provide for proper belt tracking, all other of said sprockets being free to move axially.   
     
     
       2. A sprocket and drive shaft assembly as defined in claim 1 including at least three of said sprockets, wherein said one sprocket locked against axial motion is centrally located with respect to said other sprockets. 
     
     
       3. A sprocket and drive shaft assembly as defined in claim 1 wherein said shaft has a square cross section and said sprockets are formed with square holes for sliding engagement around said shaft. 
     
     
       4. A support and drive assembly for a conveyor belt composed of link modules having intermediate sections and intermeshed end sections pivotally connected to one another, said assembly comprising, in combination: a linear rotary shaft having a substantially uniform, noncircular cross section throughout a major portion of its length;   a plurality of sprockets mounted on said shaft each including a hub, a wheel portion and teeth extending radially therefrom for supporting the end sections of the link modules of a conveyor belt and projecting into openings in the belt into driving engagement with the end sections;   said hubs being formed with an axial opening therethrough adapted to fit in driving engagement around said shaft while providing sufficient clearance between the surfaces of said holes and said shaft to permit free axial motion of said sprockets on said shaft; and   means engaged with said shaft for releasably restraining one of said sprockets against axial movement to insure proper tracking of said belt, all other sprockets mounted on said shaft being movable axially to accommodate variations in the width of the belt.   
     
     
       5. A support and drive assembly as defined in claim 4 wherein said shaft has a rectilinear cross section and said openings in said sprockets conform to said shaft. 
     
     
       6. A support and drive assembly as defined in claim 4 wherein said noncircular portion of said shaft is symmetrical with respect to the axis of rotation of said shaft. 
     
     
       7. A support and drive assembly as defined in claim 6 wherein said shaft has a substantially square cross section and said holes in said hubs are square. 
     
     
       8. A support and drive assembly as defined in claim 7 wherein said means for restraining said one sprocket against axial movement include two sets of axially spaced slots in the corners of said shaft and C rings engaged around said shaft and in said slots adjacent opposite ends of said hub of said one sprocket. 
     
     
       9. A support and drive assembly as defined in claim 4 including at least three of said sprockets mounted on said shaft including a medial sprocket restrained against axial motion and the remaining sprockets being substantially freely movable axially. 
     
     
       10. A support and drive assembly as defined in claim 9 wherein said medial sprocket is mounted to engage a belt substantially midway between the sides thereof. 
     
     
       11. A support and drive assembly as defined in claim 10 wherein said shaft has a substantially square cross section symmetrical with respect to the rotational axis of said shaft and said holes in said supports have square cross sections symmetrically located with respect to the peripheries of said sprockets. 
     
     
       12. A support and drive assembly as defined in claim 4 wherein each of said teeth includes a shoulder portion relatively wide axially, for engaging and supporting the end sections of a belt and a relatively narrow end portion for projecting into openings in the belt. 
     
     
       13. A support and drive assembly as defined in claim 12 wherein said wheel portion of each of said sprockets includes surface sections intermediate said teeth having noncircular surfaces providing clearance for the intermediate sections of the belt link modules. 
     
     
       14. A support and drive assembly as defined in claim 13 wherein said intermediate surface sections are substantially planar. 
     
     
       15. A support and drive assembly as defined in claim 12 wherein each of said sprockets includes an even number of said teeth and said end portions of alternate teeth are offset axially. 
     
     
       16. A support and drive assembly as defined in claim 4 wherein said shaft and said openings have substantially square cross sections symmetrical with respect to the axis of rotation of thereof and said sprockets are molded plastic units. 
     
     
       17. A support and drive assembly as defined in claim 16 wherein said means for restraining said one sprocket against axial movement include two sets of axially spaced slots in the corners of said shaft and .[.Crings.]. .Iadd.C ring .Iaddend.engaged around said shaft and in said slots adjacent opposite ends of said hub of said one sprocket. .[. 
     
     
       18.  A sprocket wheel of the type having a central hub, a rim circumscribing said hub, and means joining said hub and rim to one another, and comprising a first plurality of sprocket teeth and a second like plurality of sprocket teeth, both mounted on said rim and extending radially outwardly therefrom;   the teeth of said first plurality being alternatingly disposed with respect to the teeth of said second plurality around said rim;   the outwardly extending end portions of the teeth of said first plurality being spaced axially with respect to said hub, from the outwardly extending end portions of the teeth of said second plurality..]. .[.19. A sprocket wheel as defined in claim 18 wherein said first and second pluralities are equal to one another..]. .[.20. A sprocket wheel as defined in claim 18 wherein said end portions of said first plurality of teeth lie substantially in a common plane, and said end portions of said second plurality of teeth are substantially coplanar in a plane parallel   
     
     
        to and spaced from said common plane..]. .[.21.  A sprocket wheel as defined in claim 18 wherein each of said teeth includes a shoulder portion relatively wide axially with respect to said hub, and having a relatively narrow end portion..]. .[.22. A sprocket wheel as defined in claim 21 wherein said shoulder portion of each of said sprockets includes surface sections intermediate said teeth and having non-circular surfaces..].