NZ208564A - Detachable,width extending tread ring for trolley wheel - Google Patents

Description

®03564 Prir.'.iy Date(s): ...

ConipJeto Specification Filed: C'd'js: . P. U./P.tJ*. . $ Publication Date: .

P.O. Journal, Tno: 1 NEW ZEALAND PATENTS ACT, 1953 No.: Date COMPLETE SPECIFICATION "DETACHABLE TREAD" 1S JLW 1984 I/UK, EDWIN LINDSAY CAMERON, an Australian citizen, of 11 Bamfield Close, Tempiestowe, Victoria 3106, Australia, hereby declare the invention for which I / we pray that a patent may be granted to rx«/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - 208564 This invention relates to a detachable tread 5 particularly but not exclusively for attachment to the tyre and wheel assembly of a golf trolley or buggy.

It is common practice for golfers to transport their clubs on a two-wheeled buggy or trolley with an upstanding inclined handle which the golfer may either 10 pull or push to transport the clubs around the course. The buggies or'trolleys normally have small wheels that carry either narrow solid rubber tyres or narrow pneumatic tyres. n 208564 o In dry conditions where the ground is firm buggies or trolleys of the above kind provide a simple and effective means for transportation of the golf clubs and cause little damage to the grass of the tees 5 fairways, and even in some cases, greens of the golf course.

However in wet, and in particular, wintery conditions when the ground becomes soft and muddy it has o been discovered that the comparatively narrow tyres on "**" 10 the golf buggies or trolleys cause furrows in the grass surfaces. These furrows produce uneven lies and in extreme circumstances kill off the grass of the course in certain areas. Consequently in very wet and muddy conditions it is common practice for golf courses to ban 15 the use of buggies and trolleys of the above kind. By banning the use of buggies or trolleys the golfer is forced to carry the clubs, a task that can be particularly onerous for the elderly and infirmed.

One solution to the problem discussed above is 20 to provide the buggies or trolleys with wheels of greater axial width to ensure that the weight of the buggy and its contents is distributed over a greater area to reduce the damage to the grass of the golf course. However increasing the cross-sectional area of the ground contact 2 5 of the tyres increases the drag and makes the buggy or trolley more difficult to pull or push. This problem becomes particularly acute in hot and dry conditions where there is no need to use the wider tyre.

Consequently the golfer requires a buggy or trolley that 30 has narrow tyres in the summer and wide tyres in the winter.

The present invention has been brought about by . '-s consideration of these problems.

O ^!C7' 203564 According to the present invention there is provided a detachable tread for attachment to a tyre and wheel assembly of a trolley or buggy comprising an annular member in the form of a closed ring of elastic material having a radially outer ground engaging surface, and a radially inner mounting surface, the mounting surface being profiled to in use provide circumferential surface contact with the radially outer surface of the tyre and the ground engaging surface being substantially axially wider than the axial width of the mounting surface so that the tread may be stretched over the tyre on the trolley or buggy to increase the area of ground contact of the tyre.

Preferably the mounting surface comprises a pair of radially inwardly extending flanges that in ute engage the radially outer portion of the side walls of the tyre to axially locate the tread on the tyre. In a preferred embodiment an annular crown portion is provided between the radially inwardly extending flanges of the mounting surface and in use this crown portion is arranged to be in circumferential surface contact with the radially outer surface of the tyre. The crown portion may be provided with a ribbed or patterned surface to increase the frictional contact between the tread and the outer circumference of the tyre.

Preferably the tread is made of rubber or plastics. To facilitate attachment of the tread the diameter of the radially inner edge of one flange is greater than the diameter of the other flange so that the flange of greater diameter can be first stretched over the tyre. 208564 It is understood that suitable fastening means may be provided at spaced intervals to secure the radially inwardly extending flanges to the side walls of the tyre. Such fastening means may include self tapping screws or nuts and bolts that extend axially across the tyre to clamp the flanges against the tyre.

The present invention will now be described by way of example only with reference to the accompanying drawings in which:- Figure 1 is an exploded perspective view of a golf buggy tyre and wheel assembly and a detachable tread; Figure 2 is a cross-sectional view of the detachable tread; and 20856 Figure 3 is a cross-sectional view of part of a solid tyre and wheel assembly with a detachable tread attached thereto.

Figures 1 and 3 illustrate a tyre and wheel 5 assembly of a golf buggy or trolley. An axle 10 of the buggy or trolley carries a wheel having a disc 11 and annular wheel rim 12. In Figures 1 and 3 the wheel rim 12 carries a solid rubber tyre 13, however it is understood that this invention is applicable to a *'* 10 pneumatic tyre.

A detachable tread 20 constructed of rubber or plastics is arranged to be secured to the radially outer circumferential surface 21 of the tyre 13. The tread 20 comprises a radially outer ground engaging portion 22 15 that is substantially wider in the axial direction than the axial width of the tyre 13. The tread 20, in cross-sectional view as shown in Figures 2 and 3, is substantially rectangular and has on the radially inner sides thereof a mounting surface 23. In Figure 2 the 20 mounting surface 23 presents a concave crown 24 to the exterior and merges into a pair of radially inwardly extending location flanges 25 and 26. The radially inwardly extending location flanges 25 and 26 are arranged to engage the radially outer sides of the side 25 walls 27 and 28 of the tyre 13.

With the solid tyre 13 illustrated in Figures 1 and 3 the diameter of the crown 23 of the detachable tread 2 0 is arranged to be the same as the diameter of * the outer surface 21 of the tyre 13. However the 30 radially inwardly extending location flanges 25 and 26 are of smaller diameter than the diameter of the outer surface 21 of the tyre 13. Consequently the detachable tread has to be elastic so that the location flanges can be stretched over the tyre 13. To facilitate the 35 stretching of the location flanges, the flange 25, the / • *r 7 085 64 - 7 - w leading flange is of greater diameter than the other trailing flange 26 so that the detachable tread can be placed onto the tyre 13 by initially placing the leading flange 25 over the tyre. The elasticity of the 5 detachable tread ensures positive location of the tyre 13. To assist this location it is understood that suitable gripping projections may be provided on the crown 24 of the tread 20. It is further understood that the diameter of the crown 24 could be slightly less than 10 the diameter of the tyre 13 so that the tread is in a stretched condition when attached to the tyre.

With a pneumatic tyre (not shown) the concave crown of the mounting portion is arranged to be of © slightly smaller diameter than the diameter of the pneumatic tyre when fully inflated. Consequently, to attach the tread 20 to a pneumatic tyre the tyre is partially deflated thereby allowing the crown 24 and downwardly extending flanges to be placed over the outer circumference of the pneumatic tyre. The pneumatic tyre 20 is then fully inflated so that the outer circumference of the tyre is in positive and firm engagement with the mounting surface of the tread. The positive engagement of the outer circumference of the tyre with the crown and inwardly extending flanges ensures that the tread will 25 not slip off or move out of alignment with the tyre and wheel assembly. It is understood that the crown portion of the mounting surface may be provided with suitable ribs or other profiling to increase the friction between the mounting surface and the tyre to reduce the 30 likelihood of slip between the two components.

Because the pneumatic tyre may be deflated there is no need to stretch the tread over the tyre and consequently the tread may be reinforced to be inextensiblo or may be simply constructed of sufficiently strong plastics or rubber that prevents stretching of*the tread.

It is however understood that in a preferred 5 embodiment, the tread is constructed of elastic rubber or plastics to facilitate stretching of the tread onto a variety of buggy tyres. This is particularly true in the case of a solid tyre as illustrated in Figures 1 and 3.

In the preferred embodiment the detachable 10 tread is injection moulded in a porous plastics material. Polyol DR 225 is mixed in Isocyanide VM 051 both in solid form and then heated to 70°C to cause the mixture to melt. The tread is then formed by injection moulding. The speed of injection of 15 the mixture controls the porosity of the final product. It is desirable that the final product has a porosity defined by a void percsntage of about 20% to ensure the required strength and lightness. The product, at this porosity, also has the-desired degree of elasticity to 20 facilitate easy yet secure attachment to the tyre and wheel assembly. Although it is preferred that the product is injection moulded it is understood that it could be made in a continuous extended length which would be cut to length, formed into annular form and the ends 25 bonded or welded together to produce the final product.

To further locate the tread 20 on the outer surface of a solid tyre a number of fasteners such as nut and bolt assemblies (net shown) may be provided to extend axially through the mounting flanges 25 and 26 and 30 through the cross-section of the tyre. It is understood that the nut and bolt assemblies may be provided at equally spaced intervals around the circumference of the tyre and wheel assembly. It is also understood that the radially inwardly extending flanges 25 and 26 need not to £ \J6°CT!986 be continuous around the circumference of the tread but may be at suitably spaced intervals around the tread circumference.

The detachable tread described above provides a 5 ground engaging surface that is much wider than the outer circumference of the existing tyre of the buggy wheel. The design of the detachable tread is such that it is a simple exercise to attach or detach the tread. There is no need to remove the wheel or tyre of the buggy and the 10 user can simply attach or detach the tread when required. The tread has been carefully designed to ensure that it is positively located on the tyre of the buggy and in use is of sufficient width to ensure that the buggy and its contents do not cause indentation and furrowing of the 15 fairways and greens of a golf course.

There are many variations in the cross-section of solid tyres and thus it is understood that the cross-section of the mounting surface could be varied to accommodate particular solid tyres. Notwithstanding the 20 above, the elasticity of the product accommodates a large variety of irregular tyre designs.

It is understood that this invention is not limited to golf buggies or trolleys. The detachable tread could be used on many other tyre and wheel 25 assemblies on such items as prams, supermarket trolleys, wheel-barrows and many other means of transportation that use tyres of comparatively narrow cross-section.

Whilst this specification discloses the preferred embodiments of the invention it is understood 30 that many modifications and variations, not disclosed in this specification are embraced by the invention in its broadest aspect.

Claims (7)

208564 10 WHAT I CLAIM IS:

1. A detachable tread for attachment to a tyre and wheel assembly of a trolley or buggy comprising an annular member in the form of a closed ring of elastic material having a radially outer ground engaging surface, and a radially inner mounting surface, the mounting surface being with the radially outer surface of the tyre and the ground engaging surface being substantially axially wider than the axial width of the mounting surface so that the tread may be stretched over the tyre on the trolley or buggy to increase the area of ground contact of the tyre.

2. The detachable tread according to claim 1 wherein the mounting surface comprises a pair of radially inwardly extending flanges that engage the radially outer portion of the side walls of the tyre to axially locate the tread on the tyre.

3. The detachable tread according to claim 2 wherein, the diameter of the radially inner edge of one flange is greater than the diamete"r of the other flange so that the flange of greater diameter can be first stretched over the tyre.

4. A detachable tread according to either claim 2 or 3 wherein fastening means are provided at spaced intervals circumferentially around the flanges to allow the flanges to be secured to the side walls of the tyre.

5. The detachable tread according to claim 4 wherein the fastening means include self-tapping screws or nuts and bolts that extend axially across the tyre to clamp the flanges against the tyre.

6. The detachable tread according to any one of claims 1 to 5 wherein the radially inner mounting surface is provided with a ribbed or patterned surface to increase the frictional contact between the tread and the outer circumference of the tyre. profiled to provide circumferential surface contact fh I 5 208564 - 11 -

7. A detachable tread for attachment to a tyre and wheel assembly of a trolley and buggy substantially as described herein with reference to and as illustrated in the accompanying drawings. unitu iHii (6i1°day op |v A• J. PARK & SON PER AGENTS FOR THE APPtlCANTS