1 A TENSIONING ASSEMBLY FOR A CONVEYOR BELT FIELD [0001] The present invention relates to conveyor support structures that tension an associated conveyor belt. BACKGROUND [0002] In the mining industry belt conveyors are employed extensively for the purposes of transporting mined material such as coal. The belt passes along a gantry consisting of a series of gantry elements that are connected "end to end". The gantry elements are supported on trestles, each trestle assembly including two vertically extending legs. One peculiar set of the trestles with four vertically extending legs is provided with a belt tensioning mechanism including a roller about which part of the return length of the conveyor belt passes, with the roller having attached to it a weight to tension the belt. The roller is mounted in a carriage that is guideably supported in a pair of guides located between adjacent pairs of legs of the particular trestle. [0003] That portion of the belt that passes about the tensioning roller extends downwardly from a pair of adjacent rollers supported by bearings. [0004] The above mentioned conveyor structures have a number of disadvantages including complexity and cost in respect of constructing the four legged trestle with the counter weight and guides therefore, and difficulty in respect of removing the rollers from which the belt downwardly extends to the tensioning roller. OBJECT [0005] It is the object of the present invention to overcome or substantially ameliorate at least one of the above disadvantages. SUMMARY [0006] There is disclosed herein a tensioning assembly for a conveyor belt, said assembly including: a vertically extending frame; 2 a roller about which the belt is to pass and to extend upwardly therefrom, the roller being operatively associated with the frame for guided movement relative thereto along a generally vertical path, the roller having a generally horizontal rotational axis; a weight attached to the roller to tension the belt, said weight being (i) partly located above said axis so that said weight has a centre of gravity below said axis and (ii) formed of sheet material having an aperture within which said roller is located, wherein said frame includes a pair of vertical frame legs that are parallel, co-extensive and transversely spaced, with each leg having a guide portion engaging the weight to guide the weight for vertical movement relative to the legs. [0007] There is also disclosed herein a tensioning assembly for a conveyor belt, said assembly including: a vertically extending frame including a pair of generally parallel, transversely spaced and co-extensive frame legs; a tensioning weight assembly located between the legs, the tensioning weight assembly including a counterweight member having an aperture; and a roller disposed within the aperture, the roller configured to engage the belt such that the tensioning weight assembly tensions the belt, wherein each leg has a guide portion engaging the tensioning weight assembly to guide the tensioning weight assembly in vertical movement relative to the legs, said guide portions being located in a common vertical plane passing through the legs. [0008] There is further disclosed herein a conveyor assembly including: a frame along which a conveyor belt is to pass in a transport direction; a roller about which the belt passes, the roller having a generally horizontal rotational axis; a pair of bearing assemblies between which the roller passes so as to be rotatably supported thereby, each bearing assembly including a bearing base and a bearing cap and a bearing element located between the base and cap so as to be supported thereby, with the roller extending between the bearing elements so as to be rotatably supported thereby; and wherein each cap is attached to its respective base by threaded fasteners that have a longitudinal axis that is generally in the transport direction of the belt.
2a BRIEF DESCRIPTION OF THE DRAWINGS [0009] A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings wherein: 3 [0010] Figure 1 is a schematic side elevation of a conveyor assembly; [0011] Figure 2 is a schematic front elevation of the assembly of Figure 1; and [0012] Figure 3 is a schematic sectioned top plan view of the assembly of Figure 2 sectioned along the line "A-A". DESCRIPTION OF THE PREFERRED EMBODIMENT [0013] In the accompanying drawings there is schematically depicted a conveyor assembly 10. The assembly 10 includes a gantry 11 consisting of a plurality of gantry modules 12. Each module 12 includes a pair of generally parallel co-extensive side walls 13 joined by an arcuate roof 14. [0014] Each module 12 includes a longitudinally extending frame 15 that supports a plurality of rollers including rollers 16, with the rollers, including rollers 16 supporting the return length 17 of a conveyor belt 18. The delivery length 19 of the belt 18 is supported by rollers 20. [0015] Each module 12 is supported by a trestle 21, each trestle including a pair of trestle legs 22 that are generally vertically oriented, transversely spaced, generally parallel and co extensive. At least one of the trestles 21 includes a tensioning device 38. In this respect, the device 38 is operatively associated with the adjacent legs 22 to provide a tensioning assembly. Attached to each leg 22 of each tensioning assembly is a vertical guide 23. The guides 23 are operatively associated with a counter weight assembly 24 that tensions the belt 18 by having a belt portion 25 of the return length 17 pass about the tensioning roller 26 of the assembly 24. The assembly 24 further includes a counter weight member 27 that is of a metal plate construction having an aperture 28 within which the roller 27 is located. Attached to the member 27 are bearings 29 that support the roller 26 for rotation about a generally horizontal axis 30. [0016] The counter weight member 27 extends above the axis 30 while having a centre of gravity below the axis 30. [0017] Each of the guides 23 is attached to a respective one of the legs 22 so that the legs 22 and guides 23 are located generally within a common vertical plane.
4 [0018] Located towards the lower end of the legs 22 is a shield 31 within which the assembly 24 may enter while shielding personnel therefrom. [0019] The legs 22 are attached to concrete blocks 32 so as to be supported thereby. [0020] Each associated pair of legs 22 is attached to its respective module 12 by pivot assemblies 33 so that each module 12 can pivot about a generally horizontal axis relative to its associated legs 22. [0021] The rollers 16 from which the belt portion 25 depends are supported by bearings 34. The bearings 34 each have a bearing base 35 attached to an end face 36 of the frame 15, with a bearing cap 37 being secured thereto by threaded fasteners that extend axially in the direction of extension of the module 12, that is the transport direction of travel of the belt 18. By having the caps removable and no structure immediately below the rollers 16, the rollers 16 are easily removed for repair.