WO2006094350A1

WO2006094350A1 - Improved pulley tyre

Info

Publication number: WO2006094350A1
Application number: PCT/AU2006/000307
Authority: WO
Inventors: Kingsley Bruce Dyson
Original assignee: Jlv Industries Pty Ltd
Priority date: 2005-03-10
Filing date: 2006-03-09
Publication date: 2006-09-14

Abstract

An improved pulley tyre (10), the pulley tyre (10) adapted to be held to a rim, the pulley tyre (10) comprises a first circumferential recess or groove (16) which in use may accommodate, at least in part, a rope or cable (26), the circumferential recess (16) characterised in that it has provided therein a circumferential raised portion (24) itself describing a second circumferential groove (18), whereby the rope or cable (26) received by the pulley tyre (10) is received on the raised portion (24).

Description

"Improved Pulley Tyre"

Field of the Invention

The present invention relates to an improved pulley tyre. More particularly, the pulley tyre of the present invention is.of the type having a peripheral recess or groove for receiving a rope or cable.

Background Art

A variety of pulley tyre and rim configurations are presently available. These include a two piece tyre, as shown in British Patent Specification GB 1125738. The two-piece tyre is provided such that a half tyre section is first bonded to a rim half, the rim halves being brought together and fixed to a hub to provide the full pulley. The tyre halves, when the rim halves are joined to the hub, come together to form the full tyre and form a groove or recess in their circumferential face. The circumferential recess allows for the accommodation of a rope or cable.

A further prior art pulley tyre is disclosed in US Patent 5019019. This document discloses a single-piece annular tyre arranged to be held between a pair of rim halves. Again, the tyre has provided therein a circumferential recess in which a rope or cable is located during operation.

In Australian Patent 757844 to the present Applicant there is disclosed a further single-piece annular tyre. This tyre is adapted for use with a particular rim, allowing upstanding members on the axial surfaces of the tyre to engage apertures provided in the rim halves. This arrangement minimises slipping of the tyre with respect to the rim halves during operation.

It is a feature of pulley tyres of the above described type to provide a circumferential groove or recess in which is received a rope or cable during operation. The recess acts to guide and locate the rope or cable. It is the experience of the Applicant that during operation of such pulley tyres the rope or cable has a tendency to slew sideways relative to or along the axis of rotation of the pulley. It is thought that this may be due to the manner in which the cable is wound. In addition or alternately, it is thought that this behaviour may be as a result of the fact that such pulleys are often provided in pairs on a rocker arm, with the rope or cable first passing over one pulley in the pair and then over the second. It has been observed that this may cause one pulley in the pair to slew as described above relative to the other in the pair. Whatever is the case, it has been determined that there is a resulting tendency for the cable to run against one or other axial side of the circumferential recess or groove as the pulley rotates. The rotational speed of the pulley is a function of the speed of the cable and the radius at the bottom of the circumferential recess or groove, where the maximum contact pressure and minimum slip between cable and pulley tyre occurs. As the outer edges of the recess or groove rotate at the same rotational speed as the rest of the pulley, but are located further from the axis of rotation of the pulley than is the bottom of the circumferential recess or groove, the outer edges of the groove travel at a higher speed than does the cable. This causes friction between the cable and an outer portion of the "axial" side of the circumferential recess or groove in the pulley tyre, resulting in accelerated wear of the tyre in this area.

With prior art two piece pulley tyres it may have been possible to change only one half of the pulley tyre in a circumstance in which one axial side of the pulley tyre was worn. With the preferred single piece tyre this is of course not possible. If the user is to access the many benefits of the single piece tyre, it would be advantageous to provide a single piece pulley tyre that overcame the above described problems associate with uneven wear.

The historical use of softer polyurethane in the construction of two-piece pulley tyres resulted in the rope or cable settling, with use, in the centre of the circumferential recess or groove as the softness was accentuated at the join between the two tyre halves, in the centre of the recess or groove. The reinforcing band inside the single piece tyre increases resistance of the tyre material to deformation near the centre of the recess or groove, this is thought to contribute to the above mentioned problems associated with uneven wear.

The improved pulley tyre of the present invention has as one object thereof to overcome the above mentioned problems associated with the prior art.

The preceding discussion of the background art is intended to facilitate an understanding of the present invention only. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge in Australia or any other country or region as at the priority date of the application.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. The term "axial" and derivatives thereof are intended to imply the axis about which the pulley on which the improved pulley tyre is mounted and about which it is arranged to rotate in use.

Disclosure of the Invention

In accordance with the present invention there is provided an improved pulley tyre, the pulley tyre adapted to be held to a rim, the pulley tyre comprises a first circumferential recess or groove which in use may accommodate, at least in part, a rope or cable, the circumferential recess characterised in that it has provided therein a circumferential raised portion itself describing a second circumferential groove, whereby the rope or cable received by the pulley tyre is received on the raised portion.

Preferably, the accommodation of the rope or cable within the raised portion will increase the tendency of the pulley tyre to wear centrally with respect to the circumferential recess. The axial side edges of the raised portion are preferably flared towards axial sides of the first circumferential recess or groove. Still preferably, the radius described by the second circumferential groove is smaller or tighter than that described by the first circumferential recess or groove.

In one form of the present invention the improved pulley tyre further comprises a groove or slot provided substantially centrally within the means for guiding the rope or cable and extending around the entire circumference of the pulley tyre.

Preferably, the groove or slot is about 5 mm wide and 2.5 mm deep.

In accordance with the present invention there is further provided an improved pulley tyre, the pulley tyre comprising a circumferential recess which in use may accommodate, at least in part, a rope or cable, the circumferential recess characterised in that it has provided therein a means for guiding rope or cable travel, whereby the rope or cable received by the pulley tyre is first received by the means for guiding rope or cable travel within the circumferential recess.

In the course of normal operation, the means for guiding the rope or cable prevents significant contact between the rope or cable and axially outer portions of the first circumferential recess or groove, thereby substantially avoiding wear that would otherwise result from such contact. Should the passage of the rope or cable over the pulley be upset, for example by a splice in the rope or cable traversing the pulley, to the extent that the rope or cable climbs out of the means for guiding the rope or cable, the rope or cable will be prevented from climbing out of the pulley by the axially outer portions of the first circumferential recess or groove.

In one form of the present invention the means for guiding rope or cable travel comprises a groove or slot, the groove or slot being provided substantially centrally within the circumferential recess or groove and extending around the entire circumference of the pulley tyre.

Preferably, the groove or slot is about 5 mm wide and 2.5 mm deep. Brief Description of the Drawings

The improved pulley tyre of the present invention will now be described, by way of example only, with reference to one embodiment thereof and the accompanying drawings, in which:-

Figure 1 is an upper perspective view of an improved pulley tyre in accordance with a first embodiment of the present invention;

Figure 2 is a side elevational view of the improved pulley tyre of Figure 1 ;

Figure 3 is an end elevational view of the improved pulley tyre of Figure 1 ;

Figure 4 is an end elevational view of the circumferential recess of the improved pulley tyre of Figure 1 ;

Figure 5 is a cross sectional view of a circumferential portion of the improved pulley tyre of Figure 1 ;

Figure 6 is similar to Figure 5 above, other than it also showing a cross section of a cable located in the circumferential groove thereof; and

Figure 7 is a cross sectional view of a circumferential portion of an improved pulley tyre in accordance with a second embodiment of the present invention.

Best Mode(s) for Carrying Out the Invention

In Figures 1 to 6 there is shown an improved pulley tyre 10 of generally annular configuration in accordance with a first embodiment of the present invention. The pulley tyre 10 comprises an inner ridge 12, outer walls 14 arranged axially with respect to the orientation of the pulley tyre 10, a first circumferential groove 16 and a second circumferential groove 18. The pulley tyre 10 is moulded from polyurethane material and an annular steel band 20, best seen in Figures 5 and 6, is provided at a base of the inner ridge 12. The band 20 increases the strength of the pulley tyre 10 and reduces the flexing and relaxation of the polyurethane material during use.

A plurality of upstanding members 22 are provided on the axial walls 14 to facilitate positive engagement with rim halves (not shown) used to clamp the pulley tyre 10 to a pulley hub (not shown) in the manner described in Australian Patent 757844, the entire content of which is incorporated herein by reference.

The circumferential groove 16 is not strictly semicircular in shape. It in fact describes a centrally located 'flat' portion with axial or side portions that are each described by matching segments or arcs. The total axial width of groove 16 is greater than the diameter of the cable described hereinafter. The circumferential groove 18 does describe a radius, the radius being smaller or 'tighter' than that that may be said to be described by the first circumferential groove 16. The circumferential groove 18 is described by a means for guiding rope or cable travel, for example a raised portion 24 provided within the circumferential groove

16. The raised portion 24 is provided about the entire circumferential groove 16.

In this manner, a cable received within the circumferential recess 18 during use, such as would be the case when the improved pulley tyre 10 is new, will firstly wear the polyurethane of the raised portion 24. The provision of the circumferential recess 18 is expected to cause the wear to be generally centrally located relative to the circumferential recess 16, whereby wear about the circumference of the pulley tyre 10 is less likely to slew axially than in prior art polyurethane pulley tyres.

For example, if a cable 26, as shown in cross-section in Figure 6, is received within the circumferential recess 18, at first instance the initial wear will be in the raised portion 24. If the cable 26 does slew axially sideways, for example as shown by arrow 28 in Figure 6, the axial edge of the raised portion 24 will wear at first instance. The axial edges of the upstanding member are flared towards the axial sides of the circumferential groove 16, thereby effectively reinforcing those edges and allowing some level of compression therein whilst encouraging the cable 16 to become re-centred in the groove 18. Even if this non-centric wear continues, the cable 26 is ultimately encouraged to settle towards the centre of the circumferential recess 16. This is particularly the case when compared with wear patterns experienced with single piece polyurethane pulley tyres provided with only a single circumferential recess.

It is envisaged that the circumferential recess 16 and 18 may be provided in a form other than shown in pulley tyre 10. That is, the recess 16 and 18 may have a different radius, be deeper or not necessarily have a smooth radius. However, it is considered that the raised portion 24 needs to be located substantially centrally within the circumferential recess 16.

It is further envisaged that the pulley tyre 10 may be formed of other plastics or rubber materials without departing from the spirit and scope of the invention.

It is still further envisaged that the means for guiding cable travel may be constituted by one or more raised ridges, ribs or flanges extending circumferentially and within the circumferential recess 16.

In Figure 7 there is shown an improved pulley tyre 50 of generally annular configuration in accordance with a second embodiment of the present invention. The improved pulley tyre 50 is substantially similar to the improved pulley tyre 10 and like numerals denote like parts. The improved pulley tyre 50 additionally comprises a groove or slot 30 provided substantially centrally within groove 18, described by the means for guiding cable travel, and extending around the entire circumference of the pulley tyre 50.

The groove or slot 30 is about 5 mm wide and about 2.5 mm deep.

The Applicants believe the provision of such a groove or slot may allow the polyurethane of the tyre to deform and allow the cable to sink or settle into the centre of the means for guiding the rope or cable and in turn the circumferential recess or groove 18 and ultimately groove or recess 16. Additionally, it is envisaged that the means for guiding cable travel may simply comprise such a groove or slot provided substantially centrally within the circumferential recess or groove.

Modifications and variations such as would be apparent to the skilled addressee are considered to fall within the scope of the present invention.

Claims

1. An improved pulley tyre, the pulley tyre adapted to be held to a rim, the pulley tyre comprises a first circumferential recess or groove which in use may accommodate, at least in part, a rope or cable, the circumferential recess characterised in that it has provided therein a circumferential raised portion itself describing a second circumferential groove, whereby the rope or cable received by the pulley tyre is received on the raised portion.

2. An improved pulley tyre according to claim 1 , wherein the raised portion comprises axial side edges, the side edges being flared towards axial sides of the first circumferential recess or groove.

3. An improved pulley tyre according to claim 1 or 2, wherein the radius described by the second circumferential groove is smaller or tighter than that described by the first circumferential recess or groove.

4. An improved pulley tyre according to any one of the preceding claims, wherein the improved pulley tyre further comprises a groove or slot provided substantially centrally within the means for guiding the rope or cable and extending around the entire circumference of the pulley tyre.

5. An improved pulley tyre according to claim 4, wherein the groove or slot is about 5 mm wide and about 2.5 mm deep.

6. An improved pulley tyre having a circumferential recess which in use may accommodate, at least in part, a rope or cable, the circumferential recess characterised in that it has provided therein a means for guiding rope or cable travel, whereby the rope or cable received by the pulley tyre is first received by the means for guiding rope or cable travel within the circumferential recess.

7. An improved pulley tyre according to claim 6, wherein the means for guiding rope or cable travel is provided in the form of a circumferential raised portion describing a second circumferential groove, whereby the rope or cable received by the pulley tyre is received on the raised portion.

8. An improved pulley tyre according to claim 7, wherein the raised portion comprises axial side edges, the side edges being flared towards axial sides of the first circumferential recess or groove.

9. An improved pulley tyre according to claim 7 or 8, wherein the radius described by the second circumferential groove is smaller or tighter than that described by the first circumferential recess or groove.

10. An improved pulley tyre according to any one of the preceding claims, wherein the improved pulley tyre further comprises a groove or slot provided substantially centrally within the means for guiding the rope or cable and extending around the entire circumference of the pulley tyre.

11. An improved pulley tyre according to claim 10, wherein the groove or slot is about 5 mm wide and about 2.5 mm deep.

12. An improved pulley tyre according to claim 6, the means for guiding rope or cable travel comprises a groove or slot, the groove or slot being provided substantially centrally within the circumferential recess or groove and extending around the entire circumference of the pulley tyre.

13. An improved pulley tyre according to claim 12, wherein the groove or slot is about 5 mm wide and 2.5 mm deep.

14. An improved pulley tyre substantially as hereinbefore described with reference to Figures 1 to 6, or 7.