GB2143482A - Detachable tread for attachment to a tyre and wheel assembly of e.g. a golf buggy or trolley - Google Patents

Abstract

The detachable tread (20) engages the radially outer surface (21) of either a solid or pneumatic tyre (13) of the buggy wheel (11, 12) and has a ground engaging portion (22) that is substantially axially wider than the tyre (13). The tread is preferably injection moulded in elastic plastics and can be stretched onto the solid tyre of the buggy wheel. The flanges 25, 26 of the tread (20) may be fastened to the tyre (13) e.g. by threaded fasteners. For a pneumatic tyre, the detachable tread (20) may be inextensible e.g. by reinforcements and is mounted by deflating the tyre, positioning the tread and reinflating the tyre. As the width of the portion (22) of the tread (20) substantially greater than that of the tyre the tread increases the area of contact of the wheel with the ground and thus decreases the pressure on the ground as is most desirable with gold trollies. The invention can also be applied to prams, supermarket trollies and wheel-barrows. <IMAGE>

Description

SPECIFICATION Detachable tread for attachment to a tyre and wheel assembly This invention relates to a detachable tread 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 tran sport their clubs on a two-wheeled buggy or trolley with an upstanding inclined handle which the golfer may either 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.

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 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 been discovered that the com paratively narrow tyres on 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 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 particu larly onerous for the elderly and infirmed.

One solution to the problem discussed above is 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 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 has narrow tyres in the summer and wide tyres in the winter.

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

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 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 in use the tread may be secured to the tyre of a 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 use 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. In one embodiment the tread may be elastic so that it may stretched over the existing tyre on the trolley or buggy and the radially inwardly extending flanges are stretched into position against the side walls of the existing tyre. 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.

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 boits that extend axially across the tyre to clamp the flanges against the tyre.

The embodiment described above is preferably suitable for attachment to tyre and wheel assemblies that carry a solid tyre.

According to another aspect of the present invention there is provided a tyre and wheel assembly for use with a trolley or buggy comprising a wheel having mounted thereon a pneumatic tyre, a detachable tread for attachment to the tyre, the detachable tread comprising an annular member having a radially ground engaging surface and a radially inner mounting surface, the mounting surface being of diameter slightly less than the diameter of the inflated tyre and being profiled to circumferentially engage the radially outer surface of the tyre whereby the detachable tread is positioned on the tyre by initially deflating the tyre to facilitate attachment of the tread to the tyre and then inflating the tyre so that the radially outer surface of the tyre is in firm positive location against the mounting surface of the tread, the ground engaging surface being substantially axially wider than the axial width of the tyre to increase the area of ground contact of 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 Figure 3 is a cross-sectional view of part of a solid tyre and wheel assembly with a detachable tread attached thereto.

Figs. 1 and 3 illustrate a tyre and wheel 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 1 2.

In Figs. 1 and 3 the wheel rim 1 2 carries a solid rubber tyre 13, however it is understood that this invention is applicable to a 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 1 3. The tread 20 comprises a radially outer ground engaging portion 22 that is substantially wider in the axial direction than the axial width of the tyre 1 3. The tread 20, in cross-sectional view as shown in Figs. 2 and 3, is substantially rectangular and has on the radially inner sides thereof a mounting surface 23. In Fig. 2 the 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 walls 27 and 28 of the tyre 13.

With the solid tyre 1 3 illustrated in Figs. 1 and 3 the diameter of the crown 23 of the detachable tread 20 is arranged to be the same as the diameter of the outer surface 21 of the tyre 1 3. However the radially inwardly extending location flanges 25 and 26 are of smaller diameter than the diameter of the outer surface 21 of the tyre 1 3. Consequently the detachable tread has to be elastic so that the location flanges can be stretched over the tyre 1 3. To facilitate the stretching of the location flanges, the flange 25, the leading flange is of greater diameter than the other trailing flange 26 so that the detachable tread can be placed onto the tyre 1 3 by initially placing the leading flange 25 over the tyre.

The elasticity of the detachable tread ensures positive location of the tyre 1 3. 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 the diameter of the tyre 1 3 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 thread 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 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 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 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 inextensible 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 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 Figs. 1 and 3.

In the preferred embodiment the detachable tread is injection moulded in a porous plastics material. Polyol DR 225 (Registered trade mark) 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 the mixture controls the porosity of the final product. It is desirable that the final product has a porosity defined by a void percentage of about 20% to ensure the required strength and lightness. The product, at this porosity, also has the desired degree of elasticity to 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 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 (not shown) may be provided to extend axially through the mounting flanges 25 and 26 and 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 be continuous around the circumference of the tread but may be at slightly spaced intervals around the tread circumference.

The detachable tread described above provides a 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 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 fairways and greens of a golf course.

There are many variations in the crosssection 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 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 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 that many modifications and variations, not disclosed in this specification are embraced by the invention in its broadest aspect.

Claims (11)

1. A detachable tread for attachment to a tyre and wheel assembly of a trolley or buggy comprising an annular member 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 in use the tread may be secured to the tyre of a 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 in use 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 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.

4. The detachable tread according to Claim 3 wherein the crown portion is provided with a ribbed or patterned surface to increase the frictional contact between the tread and the outer circumference of the tyre.

5. The detachable tread according to any one of Claims 2 to 4 wherein the tread is elastic so that is may be stretched over the existing tyre on the trolley or buggy and the radially inwardly extending flanges are stretched into position against the side walls of the existing tyre.

6. The detachable tread according to Claim 5 wherein, 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.

7. A detachable tread according to any one of Claims 2 to 6 wherein fastening means may be provided at spaced intervals circumferentially around the flanges to allow the flanges to be secured to the side walls of the tyre.

8. The detachable tread according to Claim 7 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.

9. A tyre and wheel assembly for use with a trolley or buggy comprising a wheel having mounted thereon a pneumatic tyre, a detachable tread for attachment to the tyre, the detachable tread comprising an annular member having a radially ground engaging surface and a radially inner mounting surface, the mounting surface being of diameter slightly less than the diameter of the inflated tyre and being profiled to circumferentially engage the radially outer surface of the tyre whereby the detachable tread is positioned on the tyre by initially deflating the tyre to facilitate attachment of the tread to the tyre and then inflating the tyre so that the radially outer surface of the tyre is in firm positive location against the mounting surface of the tread, the ground engaging surface being substantially axially wider than the axial width of the tyre to increase the area of ground contact of the tyre.

10. 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.

11. A tyre and wheel assembly for fitting to a trolley or buggy, the assembly comprising a wheel, a tyre mounted on the wheel and a detachable tread mounted on and surrounding the tyre, the detachable tread being in accordance with any one of Claims 1 to 8 or Claim 10.