IlTLE OF THE INVENTION 3UIDE ROLLER BACKGROUND TO THE INVENTION rhe following discussion of the background to the invention is intended to facilitate an understanding of the present invention. However, it should be appreciated that the Discussion is not an acknowledgement or admission that any of the material referred to was Published, known or part of the common general knowledge of the person skilled in the art in any jurisdiction as at the priority date of the application. conveyances in most vertical and near vertical mine shafts are guided along and between opposing guide rails mounted on steel structures fitted along such shafts. Mine shafts may be a few hundred meters deep for shallow mines. They may even extend up to a depth of three thousand meters or more in ultra deep mines. A number of conveyances are normally used in adjacent compartments in a single mineshaft to optimise the available shaft. Each shaft compartment is fitted with its own set of guide rails. Upper and lower guide roller assemblies are fitted to the conveyances. They include rollers that guide the conveyances along opposite guide rails in travelling along their compartments. Such mine conveyances have masses ranging from a few tons up to fifty tons or more. They normally travel at speeds of about eighteen meters per second. The purpose of the guide rollers are to allow the conveyances to travel at speed in a stable way along the opposite guide rails without causing their derailment while limiting the exertion of undue lateral forces between the conveyances and the guide rails. The twist in a single steel wire hoisting rope of a conveyance exerts a moment on the conveyance that tends to rotate it around its longitudinal axis. This moment has to be resisted continuously by the guide rollers to limit physical contact between slipper plates and the guides that otherwise create excessive wear and cause impact loads. Such slipper plates serve a backup function to the guide roller assemblies. They are fitted onto the conveyances in the vicinity of the guide roller assemblies to prevent the conveyances from derailing when the guide rollers fail to adequately guide the conveyance. Such slipper plates are normally spaced at between 10 and 20 mm from the guide rail surfaces. In practice the inherent flexibility of the guide rails and their normal amount of misalignment dictates that the gap between the slipper plates and the guide rails does not exceed 20 mm.
2 During the life of a shaft the surrounding rock is often subjected to vertical and lateral novement. This and the dynamic interaction between the guide rails and the conveyances >ver time cause misalignment of the guide rails. Guide rails in a new shaft may, for example, )e aligned to within 20 mm while in older shafts such misalignment normally exceeds 20 mm. Fhe guiding arrangement of a conveyance must be able to accommodate both the nisalignment of guide rails and the inaccuracies in gauge between opposing guide rails without causing excessive and unstable lateral oscillations of the conveyance. The guide rails are normally made up from 9 to 13 meter rail lengths that are joined together with splices along the shaft. Small gaps are left between the ends of adjoining guide rails to allow for hermal expansion of the rails and inaccuracies in the supporting steelwork. Facing guide rail ends may also not be perfectly aligned if, for instance, one guide rail is worn or corroded nore than its adjoining guide rail. The guiding arrangement must also negotiate these stepped joints. Tests carried out by the inventor with the aid of high speed recording instrumentation ndicated that the generally used guide roller assemblies of which the rollers are fitted with 3olid rubber tyres are both incapable of continuously staying in contact with the guides and of keeping the slipper plates away from the guide rails. Conventionally most of the guiding functions are in fact performed by the slipper plates while the guide roller assemblies merely carry out a damping function. This leads to undesirable impact loads as well as wear on both the guides and the slipper plates. Further tests to improve the guiding function of presently used guide rollers involved the increase of the pre-tensioning and rigidity of the guide roller suspension in order to maintain guide roller contact and to prevent the slipper plates from coming into contact with the guides. These tests were very successful for the life duration of the solid rubber tyres. The guide rollers, however, failed within hours after the pre-tensioning and rigidity of the suspension were increased sufficiently for them to take over the guiding function. The solid rubber tyre failure was in response to their overheating and tearing on exposure to contact load arising movement along their guides. Pneumatic tyres and suspension such as used on road bound vehicles were considered. While having adequate strength such tyres were found to take up too much space and allow too much deflection for use in the closely confined spaces in mine shafts. It is amongst others, an object of this invention to provide guide rollers suited to the confined spaces in mine shafts that furthermore have inherent suspension capability for limiting slipper 3 )late to guide rail contact under the limited extent of permitted lateral skip displacement while urthermore limiting tyre overheating or tearing when exposed to loads during operative use. )ISCLOSURE OF THE INVENTION Throughout this specification and claims, unless the context requires otherwise, the word 'comprise" or variations such as "comprises" or "comprising", will be understood to imply the nclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. This invention relates to a rolling facility used for buffering the variation in relative lateral ,notion as regards the direction of movement between equipment fitted with one or more rolling facilities, depending on the nature of such equipment, and one or more rolling surfaces against which the one or more facilities run once in operative use. While not so limited the rolling facility of the invention is usefully applicable as a guide roller in forming part of a guide roller assembly used for guiding a conveyance such as a skip between facing guide rails along a guide shaft. Accordingly the invention resides in a rolling facility used for, amongst others, buffering the variation in relative lateral motion as regards the direction of movement between equipment fitted with one or more rolling facilities, depending on the nature of such equipment, and one or more rolling surfaces against which the one or more facilities run once, as in operative use, carried by such equipment comprising a rotor core at least incorporating if not constituting a hub via which the rolling facility is connectable via a shaft to such equipment, and being formed with a circumferential rotor core rim, and a surface engageable loop shaped formation having firm though flexible properties that is spaced from the rotor core via spacing means situated within a zone extending annularly between the rotor core rim and the loop shaped formation, characterised in that the spacing means is in the form of a set of circumferentially regularly spaced resilient spoke formations that are securely fixed between the loop shaped formation and the rim while being formed and arranged (a) to cause the formation to extend at least substantially co-axially with the axis of rotation of the rolling facility when unexposed to the exertion of an externally applied radially directed force, 4 (b) to promote the maintenance of the rotor core and the loop shaped formation about their common central plane, as extending in the rolling direction of the facility, even when the facility, once in operative use, is exposed to the exertion of an external force and (c) to limit the buckling of the spoke formations on becoming exposed to a compressing force in response to having an appropriate slenderness ratio, and in that the resilience of the spoke formations are appropriate selected, as required by the specific use of the rolling facility, to serve a suspension function for cushioning equipment to rolling surface movement in each progressively stiffening on compression each time when exposed to a compressing force during operative use of the rolling facility with the loop shaped formation being adequately firm to still extend against substantial deformation in promoting a roller type action during operative facility use. According to a preferred feature of the inventionthe spoke formations are concavely shaped to the effect of promoting the even distribution of stresses within them during their operative use According to a preferred feature of the inventionthe spoke formations are integrally moulded to the loop shaped formation and the rim According to a preferred feature of the inventionin which the loop shaped formation has adequately firm though flexible properties to result in its full off-centre displacement relative to the axis of rotation of the facility once exposed to the exertion of a radially disposed inward force while, when so exposed not necessarily remaining at least substantially fully circular, in the process causing the commensurate circumferentially disposed compression and expansion of the spoke formations. According to a preferred feature of the invention the loop shaped formation is in the form of an outer band and flexible ring combination comprising an outer band that is of firm but resilient material that is secured to a flexible ring via the inner surface of which the combination s in turn secured to the spoke formations, the outer band in serving as a solid tyre, being selected for amongst others being abrasion resistant.
5 %ccording to a preferred feature of the invention the outer band is moulded to the flexible -ing. According to a preferred feature of the invention the outer band is formed with outwardly :apering sidewalls tapering outward from its running surface at an angle of between 30 Degrees and 50 degrees serving the purpose of limiting the stresses generated there within Nhen the rolling facility is in use exposed to the application of large radially inwardly directed forces. According to a preferred feature of the invention the rotor core is constituted of the hub, as fitted with at least one radially outwardly extending annular disc along the outer edge of which disk the rotor core rim extends, in the case of the core incorporating one disk the latter extending outward from substantially the central circumferential line of the hub while when more than one, then extending generally in a regularly spaced relationship from the hub. According to a preferred feature of the invention the spoke formations are each of a material that promotes the dissipation of heat that becomes generated once the facility as suitably fitted is in use. According to a preferred feature of the inventionthe rolling facility is in the form of a guide roller of the kind used for guiding a conveyance along a guide shaft by way of suitably fitted guide roller clusters forming part of roller assemblies running along opposite guide rails extending along such shaft. The invention will be more fully understood in the light of the following description of one specific embodiment BRIEF DESCRIPTION OF THE DRAWING The description is made, with reference to the accompanying drawings. In the drawings Figure 1 shows a rolling facility, according to the invention, in the form of a guide roller of the kind amongst others used in guide roller assemblies to guide a conveyance along a guide shaft in conventionally running between facing guide rails, in side elevation, Figure 2 shows the guide roller of figure 1 along section line A-A in figure 1, Figure 3 shows a typical guide roller cluster forming part of a guide roller assembly as securable to a shaft bound conveyance via an assembly bracket (not shown in the drawing) also forming part of the assembly, and 6 -igure 4 diagrammatically explains the functioning of the guide roller. )ETAILED DESCRIPTION OF THE DRAWINGS Referring to the drawings a rolling facility, according to the invention, in the form of a guide -oller of the kind used in guide roller assemblies, the latter of which a plurality are used for guiding a conveyance such as a skip along a guide shaft, such as a mining shaft, is generally ndicated by reference numeral 10. rhe roller 10 comprises a rotor core 12 constituted from a hub 14 fitted with a ;ircumferentially extending centrally mounted radial disk 16 presenting a circumferential rim 18 along its outer edge and a firm though flexible surface engageable loop shaped formation n the form of an outer band and flexible ring combination 20 that is spaced from the rotor :ore 12 by resilient spacing means generally indicated by reference numeral 22 that serves a cushioning or suspension function during use of the roller 10 as operatively fitted and that is moulded between the rim 18 and the combination 20. The spacing means 22 as of suitably selected rubber also serves a heat dissipation function. The combination 20 is formed to co-axially extend about the axis 21 of rotation of the roller 10 when unexposed to the exertion of an externally applied radially directed force. It is adequately firm but somewhat flexible to extend against substantial though preferably not more that marginal deformation when becoming exposed to the exertion of such radial force. When so exposed it becomes displaced off-centre relative to the axis 21, as discussed below, under such conditions involving the suspension effect of the spacing means (22). When exposed to a large force the combination 20 may thus not necessarily retain its fully circular shape. The combination 20 is in the form of an outer band as provided by a solid rubber tyre 24 moulded to a flexible ring 26. In use the ring 26 also serves a heat dissipation function in conducting generated heat away from the tyre 24. The firmness though limited flexibility of the combination 20 is mainly brought about by the properties of the ring 26. The tyre 24 is formed with outwardly tapering sidewalls 28 tapering at an angle of in the order of 45 degrees to its rolling surface 30. The object of the tapering is to accommodate the stresses generated within the tyre 24 when the roller 10, as in use, becomes exposed to the application of large radially applied axially directed forces as brought about by the relative lateral displacement of a conveyance such as an ore skip conventionally fitted with guide roller assemblies (not shown) each incorporating a roller cluster 32 constituted of rollers 10 as discussed below.
7 The tyre 24 is less resilient than the spacing means 22 as it is required to be both of high strength and wear resistant whereas the function of the spacing means 22 is to serve a suspension effect and to be able to promote the dissipation of heat generated by its resilient ,ushioning movement during use as well as any heat reaching it from the rotor core 12. As shown in figures 1, 2 and 4 the spacing means 22 is in the form of circumferentially arranged regularly spaced resilient spoke formations 40 each appropriately moulded at its apposite ends. The slenderness ratio of the spoke formations 40 (being each's effective ength divided by its smallest width) are adequately large to prevent their buckling on Becoming exposed to compressing forces. The spoke formations 40 are concavely formed as shown by reference 40.1, whether narrowing fully circumferentially between flared ends or anly along opposite sides along the plane of rotation of the roller 10. The spacing between the spoke formations 40 furthermore provides sufficient air circulation to promote heat dissipation to the environment. The radial disk 16 is formed with a series of circumferentially spaced apertures 42 promoting the dissipation of heat generated in the hub 14 once the roller 10 is in operative use. As shown in figure 2 the radial disk 16 in fact constitutes an inner band 16.1 integrally extending from the hub 14 and an outer band 16.2 integrally formed with the rim 18 while being circumferentially bolted to the inner band 16.1. This enables its release from the hub and inner band combination permitting the replacement of the hard working part of the roller 10, i.e. from the rim 18 outward. Instead of a single disk 16 the rotor core 12 can incorporate two disks that are regularly spaced relative to one another. This is typical for a roller that buffers the inter guide rail movement of a conveyance moving along a shaft. In referring to figure 3 the cluster 32 is thus assembled to a bracket (not shown) in forming a guide roller assembly (not shown) conventionally fitted at upper and lower central positions along opposite sidewalls of a conveyance such as a skip (not shown). The guide roller assemblies run along conventionally secured facing guide rails 44. Two of the rollers 10.1 of each assembly conventionally run along opposite faces 46 of its guide rail 44 while a further roller 10.2 runs along its frontal face 48. As the rollers 10.2 must accommodate larger forces as created by relative lateral movement between the skip and the rails they are normally fitted with twin disk layouts while the roller 10.1 is fitted with a single disk 16. In referring to figure 4 during operative use of a guide roller assembly (not shown) incorporating rollers 10 of the invention, its outer band and flexible ring combination 20 when 8 not urging against its rail 44, runs symmetrically about the axis 21, as shown in figure 4(a) As soon as the conveyance (not shown) to which it is fitted via its assembly is exposed to relative lateral motion in the direction of arrow 50, as perhaps brought about by non-linearity along the rail 44, the motion is required to be cushioned. This is accomplished by the suspensive effect of the spoke formations 40 and somewhat supplemented by the flexibility of the ring 26 in causing the outer band and flexible ring combination 20 to move appropriately off centre with respect to the axis 21, as shown in figure 4(b) in turn involving the commensurate circumferentially disposed compression and expansion of the spoke formations 40. In serving a suspension function the spoke formations 40 consequently progressively stiffen on compression each time when exposed to a compressing force during operative use of the roller 10, as shown by spoke formations 40.2 in figure 4(b). Such progressive compression and in response to being concavely shaped, cause the effective cross sectional area of the formations 40 to increase rapidly in turn resulting in their resistance to compression to increase exponentially. This limits excessive compression of the spoke formations 40, in turn promoting the suspensive action of the roller 10 once in operative use. The spoke formations 40 therefore provide sufficient flexibility and damping for small movements but for deflections approaching 10 mm they become adequately stiff to guide a conveyance against slipper plate to guide rail contact. The spoke formations 40 also provide stability under compression to prevent them becoming buckled when compressed or when they are subjected to forces that are exerted against the common plane of roller 10 as extending in its rolling direction. In addition the concave shapes of the spoke formations 40 promote the even distribution of stresses within them during use of the roller 10. While the rollers of conventional roller assemblies are displaceably mounted to their brackets via displacing mechanisms the advantage of the invention as specifically described is found in the inherent resilience of the rollers as such accommodating lateral conveyance displacement thus potentially dispensing with the displacing mechanisms. This substantially simplifies the mechanism of the roller assemblies. It will be appreciated that the conventional rigid rollers of existing assemblies can simply also be replaced by the rollers of the invention in such way increasing the overall cushioning effect of such assemblies. A further advantage of the rollers of the invention is found in their ability to effectively dissipate heat amongst others serving to prolong their service life. The present invention is not to be limited in scope by the specific embodiment described herein. The embodiment is intended for the purpose of exemplification only. Functionally 9 equivalent components and methods are clearly within the scope of the invention as described herein.