PULLEY TYRE RIM CONFIGURATION

Abstract: A pulley comprising a hub (12) having a substantially cylindrical outer face and a pair of rim halves (11a and 11b) adapted to be mounted to the hub and having opposed inner axial faces which are divergent with respect to each other, a separable pulley tyre (13) having a cross-sectional configuration corresponding substantially to the space defined between the hub and the inner axial faces of the rimmed halves and having an inner circumference whereby the tyre is snugly received on the hub and is clampingly received between the rim halves said tyre having a reinforcing ring (15) located at or adjacent the inner circumference of the tyre, the outer circumference of the tyre being formed with a peripheral groove (14) for accommodation of a rope or cable.

Description: PULLEY TYRE RIM CONFIGURATION THIS INVENTION relates to pulleys and in particular pulleys which have a peripheral recess or groove for receiving a rope or cable. Prior art pulleys are exemplified by the disclosure in GB1125738 where the rim comprises a pair of opposed rim halves which are fixed to a hub to form the outer half of the pulley. Each rim half has bonded thereto a half tyre section which when the rims are bolted to the hub together form a complete tyre having a peripheral recess for accommodation of a rope or cable which is substantially concentric with the surface of the rim halves and hub. The difficulties with the prior art as described above have resulted from the interface between the two tyre halves fracturing due to the lack of continuation of the section and support provided at the junction therebetween. In one form the invention resides in a pulley comprising a hub having a substantially cylindrical outer face and a pair of rim halves adapted to be mounted to the hub and having opposed inner axial faces which are divergent with respect to each other, a separatable pulley tyre having a cross-sectional configuration corresponding substantially to the space defined between the hub and the inner axial faces of the rimmed halves and having an inner circumference whereby the tyre is snugly received o the hub and is clampingly received between the rim halves said tyre having a reinforcing ring located at or adjacent the inner circumference of the tyre, the outer circumference, of the tyre being formed with a -peripheral groove for accommodation of a rope or cable. According to a preferred feature of the invention the tyre is formed from an elastomeric material. According to a further preferred feature of the invention a layer of elastomeric material is located between the inner circumference of the reinforcing ring to define the inner circumference of the tyre. According to a preferred feature of the previous feature the layer of elastomeric material has a greater resilience and/or may be less hard than the elastomeric material forming the pulley tyre. According to a further preferred feature of the invention the axial faces of the tyre are formed of an elastomeric material of contrasting colour to the elastomeric material forming the body of the tyre. According to a preferred feature of the previous feature the elastomeric material at its outer axial faces of the tyre have a greater strength or hardness than the elastomeric material forming the body of the tyre. According to a preferred feature the reinforcing ring is formed of an elastomeric material of similar composition to that of the tyre but having a greater strength or hardness. According to a preferred feature of the previous feature the reinforcing ring extends over the inner circumference of the tyre and partially over each axial face. According to a further preferred feature the axial faces of the tyre are formed of an elastomeric material having a greater strength or hardness than the elastomeric material forming the main body of the tyre and a further layer of elastomeric material is located between the inner circumference of the tyre and reinforcing means and is formed of a material having a differing strength or hardness from the main body of the tyre. A further difficulty of the prior art resides in the feature that a large portion of the cross sectional! area of the tyre is occupied by the peripheral groove and therefore the degree of wear which can be tolerated before the rope or cable engages the rim half is significantly reduced. According to a further preferred feature of the invention the cross sectional area of the peripheral groove is less than half of the overall cross sectional area of the tyre. According to a further preferred feature of the invention the peripheral groove can be located to one side of the outer circumference of the tyre. In another form the invention resides in a pulley tyre which is be received on a hub having a substantially cylindrical outer face and between a pair of rim halves which are adapted to be mounted to each axial face of the hub whereby the opposed inner axial faces of the rim halves are in opposed relation to each other and are divergent with respect to each other, said tyre having an inner circumference whereby the tyre is snugly received over the hub and the lateral dimensions of the tyre being such that the tyre is clampingly received between the rim halves, said tyre being formed of an elastomeric material and having a reinforcing ring located at or adjacent the inner circumference of the tyre, the outer circumference of the tyre being formed with a peripheral groove which is adapted to receive a rope or cable. According to a further preferred feature of the invention the cross sectional configuration of the tyre is substantially trapezoidal and the cross sectional configuration of the peripheral groove is substantially circular. The invention will be more fully understood in the light of the following description of one specific embodiment. The description is made with reference to the accompanying drawings of which:- Figure 1 is a cross sectional elevation of a pulley according to the embodiment; Figure 2 is a cross sectional elevation of a tyre according to the embodiment of figure 1; Figure 3 is a cross sectional elevation of an alternative form of tyre; Figure 4 is a cross sectional elevation of a third alternative form of tyre; Figure 5 is a cross sectional elevation of a fourth alternative form of tyre; and Figures 6a and 6b are comparative drawings of the tyre according to the embodiment and according to the prior art referred to above. The embodiment shown at figure 1 comprises a pulley having a substantially circular pulley hub 12 which is adapted to be received upon a support shaft (not shown) . The outer c:ϊ cu ference of the hub 12 is substantially cylindrical. The hub supports a pair of rim halves 11a and lib in substantially opposed relationship whereby the inner axial face of the rim halves are opposed to each other and are divergent with respect to each other to define a substantially trapezoidal space between themselves and the hub outer circumference. The rim halves are retained on the hub by means of bolts 17 or similar fixing means. The pulley of the embodiment further comprises a tyre which is formed of an elastomeric material such as polyurethane and has a cross-sectional configuration which is substantially complementary to the trapezoidal space defined between the hub 12 and the rim halves 11a and lib and which is itself substantially trapezoidal. The inner circumference of the tyre is such that the tyre is snugly received over the hub 12 while the lateral dimensions of the tyre and the configuration between the inner circumference of the tyre and the outer axial faces facilitate clamping engagement of the tyre 13 between the rim halves 11a and lib. The outer circumference of the tyre is formed with a peripheral groove 14 of substantially part circular configuration which is adapted to receive a pulley rope, cable, belt or the like. The cross sectional area of the peripheral groove 14 is significantly less than the cross sectional volume of the tyre whereby the sides of the peripheral groove are spaced significantly from the sides of the tyre and the base of the groove 14 is spaced a significant distance from the base of the tyre. The tyre accommodates a reinforcing ring 15 which is located adjacent the inner circumference of the tyre and may be formed of any suitable reinforcing material such as metal, a fabric web, a metal mesh or alternatively of an elastomeric material similar to that of the main body of the tyre but of a greater strength or hardness . The inner circumference of the tyre is spaced inwardly from the reinforcing ring 15 and is formed of an inner layer 16 formed of the same elastomeric material of the main body of the tyre which may be softer and/or move resilient than the main body of the tyre. On assembling a pulley according to the embodiment the tyre is snugly fitted over the outer circumference of the hub 12 and the rim halves 11a and lib are mounted to the hub 12 by utilisation of the fixing means 17 and are brought into clamping engagement with the hub. As a result the tyre is snugly clamped the tyre therebetween the rim halves. Because of the tapered complementary configuration of the side walls of the tyre and the rim halves any radially inward force applied to the tyre by a pulley rope serves to bring the tyre into greater clamping engagement with the rim halves 11a and lib. The annular reinforcing rings 15 serves in preventing tangential extrusion of the tyre an application of the radial inward force which would otherwise result in deformation and stretching of the tyre and subsequent disengaging of the tyre from the hub and rim halves. The inner layer 16 of elastomeric material defines a locking ring which serves in insulating the pulley rim halves and the hub from any vibration created by engagement of the tyre with a pulley rope and serves in ensuring a strong frictional engagement between the outer circumference of the hub 12 and the inner circumference of the tyre 13. Due to the differing geometric configurations of the tyre and the peripheral groove " 14 and the significant difference between the cross sectional area of the peripheral groove 14 and the tyre 13 the walls of the peripheral groove are spaced significantly from the inner circumference of the tyre and the outer axial faces of the tyre. As a result of such as the tyre wears in use the groove will increase in its dimensions either downwardly or laterally or both downwardly and laterally and a greater volume of material is available for wear before the walls of the peripheral groove encounter the ring halves 11a and lib. The form of the tyre shown at figure 1 is illustrated at figure 2. It should be appreciated that the inner layer 16 of elastomeric material which defines the locking ring of the tyre may be formed of the same elastomeric material as that forming the body of the tyre or alternatively it may be formed of a softer or harder elastomeric material if desired. If desired the axial outer faces of the tyre may be formed of an elastomeric material having the same hardness as that of the main body of the tyre but of a differing and/ or contrasting colour to provide an indication of wear. A second alternative form of the tyre is shown at figure 3 where the reinforcing ring 15 is located at the inner circumference of the tyre and is formed of a similar elastomeric material to that of the main body of the tyre but a material having a greater strength or hardness. In addition the reinforcing ring 15 extends over the inner circumference of the tyre and over each axial face. If desired the material which forms the reinforcing ring 15 also has a contrasting colour to that of the main body of the tyre. This feature provides a visual indication when the peripheral groove 14 has worn to such an extent that it extends to the reinforcing ring. A third alternative form of tyre is shown at figure 4 and comprises a variation of the tyre as shown at figure 2 where the axial faces 18 of the tyre are formed with an elastomeric material having a greater hardness or strength to provide for additional reinforcement. In addition if desired the elastomeric material formed on each axial face may have a differing colour to provide an indication of wear. It is a property of rope pulley systems that due to the twist in the rope that on the rope passing over a pulley the rope has an inherent tendency to move to one side of the pulley and cause greater wear to one side of the pulley. This tendency can be enhanced by the geometry of the pulley system. In such cases it may be preferable to locate the peripheral groove towards the opposite side of the tyre to the direction in which the pulley is likely to wear in order to increase the volume of material available for wear. Figures 6a and 6b are comparative drawings of a tyre according to the embodiment and a tyre according to the prior art as exemplified by GB1125738 and illustrates the degree of wear that is available to a pulley rope in a tyre according to the embodiment as shown at figures 6a compared to the pulley tyre of GB1125738. Furthermore because of the integral nature of the tyre the wear of the tyre is improved over that of GB1125738 which provides for an interface between two tyre halves which is substantially unsupported and as a result of that lack of support will lead to fracturing of the tyre material at the interface between the tyre halves and the peripheral groove. Furthermore when the life of the tyre of the present embodiment has been completed it is merely necessary to disassemble the pulley to remove the worn tyre and reinsert a new tyre. In the case of the prior art is exemplified by GB1125738 it is necessary to remove each of the rim halves, remove the elastomeric material which forms the tyre " halves and which is bonded to each of the rim halves and then remould fresh material to form each tyre half on each rim half. It should be appreciated that the scope of the present invention need not be limited to the particular scope of the embodiment described above.

Claims: £t-AtM3-' 1. A pulley comprising a hub having a substantially cylindrical outer face and a pair of rim halves adapted to be mounted to the hub and having opposed inner axial faces which are divergent with respect to each other, a separatable pulley tyre having a cross-sectional configuration corresponding substantially to the space defined between the hub and the inner axial faces of the rimmed halves and having an inner circumference whereby the tyre is snugly received on the hub and is clampingly received between the rim halves said tyre having a reinforcing ring located at or adjacent the inner circumference of the tyre, the outer circumference of the tyre being formed with a peripheral groove for accommodation of a pulley or cable. 2. A pulley as claimed at claim 1 wherein the tyre is formed from an elastomeric material. 3. A pulley as claimed at claim 1 or 2 wherein a layer of elastomeric material is located between the inner circumference of the reinforcing ring to define the inner circumference of the tyre. 4. A pulley as claimed at claim 3 as dependent on claim 2 wherein the layer of elastomeric material has a greater resilience and/or is less hard than the elastomeric material forming the pulley tyre. 5. A pulley as claimed at any one of claims 2, 3 or 4 wherein the axial faces of the tyre are formed of an elastomeric material of contrasting colour to the elastomeric material forming the body of the tyre to indicate wear. 6. A pulley as claimed in claim 5 wherein the elastomeric material at its outer axial faces of the tyre have a greater strength or hardness than the elastomeric material forming the body of the tyre. 7. A pulley as claimed at any one of claims 2, 3, 4, 5 or 6 wherein the reinforcing ring is formed of an elastomeric material of similar composition to that of the tyre but having a greater strength or hardness. 8. A pulley as claimed at claim 7 wherein the reinforcing ring extends over the inner circumference of the tyre and partially over each axial face. 9. A pulley as claimed at claim 2 wherein the axial faces of the tyre are formed of. an elastomeric material having a greater strength or hardness than the elastomeric material forming the main body of the tyre and a further layer of elastomeric material is located between the inner circumference of the tyre and reinforcing means and is formed of a material having a differing hardness from the main body of the tyre. 10. A pulley as claimed at anyone of the preceeding claims wherein the cross sectional are of the peripheral groove is less than half of the overall cross sectional area of the tyre. 11. A pulley as claimed at anyone of the preceeding claims wherein the peripheral groove is located to one side of the outer circumference of the tyre. 12. A pulley tyre which is be received on a hub having a substantially cylindrical outer face and between a pair of rim halves which are adapted to be mounted to each axial face of the hub whereby the opposed inner axial faces of the rim halves are in opposed relation to each other and are divergent with respect to each other, said tyre having an inner circumference whereby the tyre is snugly received over the hub and the lateral dimensions of the tyre being such that the tyre is clampingly received between the rim halves, said tyre being formed of an elastomeric material and having a reinforcing ring located at or adjacent the inner circumference of the tyre, the outer circumference of the tyre being formed with a peripheral groove which is adapted to receive a rope or cable. 13. A pulley tyre as claimed at claim 12 wherein a large portion of the cross sectional area of the tyre is occupied by the peripheral groove and therefore the degree of wear which can be tolerated before the rope or cable engages the rim half is significantly reduced. 14. A pulley tyre as claimed at claim 12 or 13 wherein the cross sectional area of the peripheral groove is less than half of the overall cross sectional are of the tyre. 15. A pulley tyre as claimed at claim 12, 13 or 14 wherein the peripheral groove is located to one side of the outer circumference of the tyre. 16. A pulley tyre as claimed at any one of claims 12 to 15 wherein the cross sectional configuration of the tyre is substantially trapezoidal and the cross sectional configuration of the peripheral groove is substantially circular. 17. A pulley tyre as claimed at any one of claims 12 to 16 wherein the tyre is formed from an elastomeric material. 18. A pulley tyre as claimed at claim 17 wherein a layer of elastomeric material is located between the inner circumference of the reinforcing ring to define the inner circumference of the tyre. 19. A pulley tyre as claimed at claim 18 wherein the layer of elastomeric material has a greater resilience and/or is less hard than the elastomeric material forming the pulley tyre. 20. A pulley tyre as claimed at claim 17, 18 or 19 wherein the axial faces of the tyre are formed of an elastomeric material of contrasting colour to the elastomeric material forming the body of the tyre. 21. A pulley tyre as claimed at claim 20 wherein the elastomeric material at its outer axial faces of the tyre have a greater strength or hardness than the elastomeric material forming the body of the tyre. 22. A pulley tyre as claimed at any one of claims 17 to 21 wherein the reinforcing ring is formed" " of an elastomeric material of similar composition to that of the tyre but having a greater strength or hardness. 23. A pulley tyre as claimed at claim 22 wherein the reinforcing ring extends over the inner circumference of the tyre and partially over each axial face. 24. A pulley tyre as claimed at claim 17 wherein the axial faces of the tyre are formed of an elastomeric material having a greater strength or hardness than the elastomeric material forming the main body of the tyre and a further layer of elastomeric material is located between the inner circumference of the tyre and reinforcing means and is formed of a material having dif ering strength or hardness from the main body of the tyre. 25. A pulley substantially as herein described. 26. A pulley tyre substantially as herein described.

Inventors: JONES HARRY ANTHONY THOMAS, JONES, HARRY, ANTHONY, THOMAS
Applicants: JONES HARRY ANTHONY THOMAS, JONES, HARRY, ANTHONY, THOMAS
Application year: 1988
Main classification: F16H55
IPC codes: F16H55