This invention relates to a wear ring for a vehicle road wheel, as well as a vehicle road wheel incorporating the wear ring. The wear ring is applicable to road wheels of tracked vehicles, such as armoured vehicles, and it will be convenient to hereinafter disclose the invention in relation to that exemplary application. However, it is to be appreciated that the invention is not limited to that application.

Description of the Prior Art

The following discussion of the background to the invention is intended to facilitate an understanding of the 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 as at the priority date of the application.

Tracked armoured vehicles employ a versatile traction system enabling on- and off-road travel. One system involves a series of on-road wheels mounted along each side of the vehicle. The wheels in each series are arranged in coaxial pairs, with the wheels of each pair being mounted in closely spaced apart facing relation so as to define gaps there between. Each wheel has a metal rim and a peripheral rubber tyre mounted on the rim.

An endless tracked chain is fitted about each. series of on-road wheels to enable off-road travel of the vehicle. Each chain is formed of pivotably interconnected links over which the wheels roll during travel. Guide horns project inwardly from the links and move through the gaps between the road wheel pairs during vehicle travel. These horns act to retain and guide the tracked chains on the road wheels.

A problem with this traction system is that the guide horns tend to scrape and rub on the oppositely facing sides and edges of the wheel rims defining the gap through which the horns move. That scraping and rubbing generates noise and vibration which is transmitted to the vehicle body causing some deterioration in the quality of vehicle ride. That interference between the guide horns and wheels also leads to abrasive wear and eventual destruction of the

To facilitate monitoring of the life of the wheel rims, and thus implementation of a regulated wheel replacement program, sacrificial wear rings have been fitted to that side of the wheel rims defining the gap and exposed to engagement by the guide horns. One arrangement involves riveting a steel ring to the exposed side of the wheel rim. In another arrangement, metal spray has been applied to the rims in order to build up a wear ring. With these arrangements, the guide horns engage those wear rings, rather than the actual wheel rims, so that the wheel rims are protected from abrasive wear.

The provision of those wear rings is a separate manufacturing step that adds to the overall wheel cost.

The useful life of the wheels to which the wear rings are mounted is assessed by periodically measuring the remaining thickness of the rings. That is usually carried out manually with large spring callipers which reach around the wheel rim to measure the distance between the inside surface of the rim and the exposed wear face of the wear ring located on the outside surface of the wheel rim. That measurement is typically taken at four places around the rim in order to make a thorough assessment.

When the measured distance reaches a predetermined minimum value, equating with maximum wear of the ring without damaging the rim, the wheels can be replaced. Planned replacement of the wheels before the rims start to wear preserves those rims for refurbishment of the wheels for subsequent re-use.

Accurate assessment of the useable life in situ, i.e. with the wheels and chains mounted on the vehicle, is problematical. In particular, it can be difficult to determine whether the callipers have been properly positioned against the opposing wheel rim surfaces. Moreover, readings from the callipers are sometimes prone to misinterpretation by the operators, particularly if the wear to the wear rings is uneven or erratic.

SUMMARY OF THE INVENTION

An object of the present invention, is the provision of a wear device that gives a simple indication on the wear condition of the road wheels of tracked vehicles.

Another object of the present invention is the provision of a road wheel for tracked vehicles in which its useable life can be readily and accurately assessed.

A further object of the present invention is the provision of a road wheel for tracked vehicles which is simple to manufacture and offers manufacturing cost savings.

Yet another object of the present invention is the provision of a road wheel for tracked vehicles which exhibits improved ride quality.

In one aspect, the present invention provides a wear device for a road wheel of a tracked vehicle, the wear device including: a wear ring for mounting at a side of the rim of the wheel; and wear indication means providing an indication of abrasive wear of the wear ring.

In another aspect, the present invention provides a road wheel for a tracked vehicle, the wheel including: a wheel rim; a tyre on the wheel rim; and, the above wear device mounted at a side of the wheel rim. In a further aspect, the present invention provides a road wheel for a tracked vehicle, the wheel including: a wheel rim; a tyre on the wheel rim; and, a wear ring bonded to a side of the wheel rim.

In yet another aspect, the present invention provides a road wheel for a tracked vehicle, the wheel including: a wheel rim; a tyre on the wheel rim; and, a wear ring mounted at a side of the wheel rim, wherein damping material is interposed between the wear ring and wheel rim periphery to provide a damping effect there between.

Preferably, the wear indication means provides a visual indication of abrasive wear of the wear ring. In at least one preferred form, the wear indication means provides an indication of a predetermined extent of abrasive wear of the wear ring.

Preferably, the wear ring has opposed inner and outer surfaces, respectively facing toward and away from the outside of the wheel rim in use.

The outer surface provides a wear face exposed to abrasive wear. The wear indication means preferably provides an indication of wear to the wear surface of the wear ring.

Preferably, wear indication means includes at least one wear indication member in the wear ring. In one preferred form, the wear indication member is visibly exposed by wear to the wear face of the wear ring to provide a wear condition indication. In another preferred form, the wear indication member is progressively worn away as the wear face of the wear ring wears away to provide a wear condition indication.

In at least one preferred form, the or each wear indication member is an indication insert in the wear ring. The or each indication insert is fitted into a or a respective hole in the wear ring. The or each hole extends from an open end on one surface of the wear ring into the wear ring to a blind end, in this form.

In one preferred arrangement, the holes and indication inserts all extend the same distance into the wear ring so as to all provide the same indication of the wear condition of the wear ring. In another preferred arrangement, the holes and indication inserts extend varying distances into the wear ring so as to provide different indications of the wear condition of the wear ring.

Preferably, the or each insert has a colour that visibly contrasts with the colour of the wear ring to provide a visible wear condition indication. In one preferred form, the or each insert is differently coloured, the different colours representing different conditions of wear of the wear ring. Preferably, the wear ring is bonded onto the wheel rim with a layer of damping material therebetween. In one preferred arrangement, the tyre is moulded onto the wheel rim, and the wear ring is bonded into position during moulding of the tyre.

DESCRIPTION OF THE DRAWINGS

The following description refers to a preferred embodiment of the wear device and road wheel of the present invention. To facilitate an understanding of the invention, reference is made in the description to the accompanying drawings where the device and wheel are illustrated in that preferred

embodiment. It is to be understood that the device and wheel are not limited to the preferred embodiment as hereinafter described and as illustrated in the drawings.

In the drawings: Fig. 1 is a front view of a vehicle road wheel, incorporating a wear device, according to a preferred embodiment of the present invention;

Fig. 2 is a cross-sectional view through Section N-Il of Fig. 1 ; and Fig. 3 is an enlarged view of the wheel rim region of Fig. 2.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENITON

Referring initially to Fig. 1 of the drawings, there is generally shown a single road wheel 1 for a tracked vehicle (not shown).

The wheel 1 is of conventional construction, well known to those skilled in the relevant art. In the exemplary application, that wheel 1 includes a central disc 2 having a concentrically arranged series of mounting holes 3 for mounting the wheel 1 to an axle hub (not shown). A rim flange 4 extends about a periphery 5 of the disc 2 and provides the wheel rim 6 on which a tyre 7 is mounted. In the exemplary application, the rim flange 4 extends axially from one side (the inside) 8 of the disc 2. In use of the wheel 1 , the other side (the outside) 9 of the disc 2 faces the outside 9 of the disc 2 of another wheel 1 which together form a coaxial pair of wheels 1. The outsides 9 define between them a gap through which guide horns of a tracked chain pass. As a consequence, it is that outside 9 of the rim 6 which is exposed to abrasive engagement by the guide horns.

The disc 2 and rim flange 4 are manufactured in one piece, such as by casting from metal, or forging.

The tyre 7 is of solid construction, and moulded from rubber. In order to protect the wheel rim 6 from abrasive wear by the guide horns, a wear device 10 is fitted to the wheel 1. The wear device 10 is shown in greater detail in Figs. 2 and 3, and includes a sacrificial wear ring 11 mounted at the rim 6 of the wheel 1.

The wear ring 11 has opposed inner and outer surfaces 12,13, respectively facing toward and away from the outside 9 of the wheel rim 6 in use. Thus, the wear ring 11 overlies the outside 9 of the wheel rim 6, and the outer surface 13 provides a wear face 14 which is exposed to the scraping, rubbing and other abrasive engagement of the guide horns of the chain links during use of the wear device 10 and wheel 1 in the exemplary application.

The wear device 10 includes wear indication means 15 for providing an indication of abrasive wear of the wear ring 11. The wear indication means 15 provides a visual indication of that abrasive wear in this embodiment. The wear indication means 15 provides an indication of a predetermined wear condition of the wear ring 11. The indication means can also provide an indication of a predetermined extent of that wear condition.

In this embodiment, the wear condition monitored by the indication means

15 is the thickness of the wear ring 11 as measured between the inner and outer surfaces 12,13. Thus the indication means 15 provides an indication of wear to the wear face 14 of the wear ring 11. The indication means 15 also provides an indication of the extent of wear in the thickness of the wear ring 11.

In this embodiment the indication means 15 provides an indication that wear has reached a stage at which the wheel 1 requires replacement (worn condition). Thus, in the worn condition, the wear ring 11 is worn to a predetermined maximum extent. In the exemplary application, that worn condition represents abrasive wear of the wear ring 11 to an extent just prior to commencement of wear to the outside 9 of the wheel rim 6.

The indication means 15 may also provide an indication of progressive wear (wearing condition) up to the worn condition. Thus, the indication means 15 can provide an indication of abrasive wear of the wear ring 11 as it progresses toward the worn condition.

The indication means 15 includes at least one indication member 16 in the wear ring 11. In one arrangement (as shown), the indication member 16 is visibly exposed by wear to the wear face 14 of the wear ring 11 to provide a wear condition indication. In another arrangement (not shown), the indication member 15 is progressively worn away as the wear face 14 of the ring 11 wears away, in order to provide that wear condition indication. In a further arrangement (not shown), the indication member 15 is initially visibly exposed,

and then progressively wears away by wear of the wear face 14 so as to provide the wear condition indication.

In this embodiment, a series of indication members 16 are provided in spaced apart locations about the wear ring 11. In the exemplary application, at least four to six (as shown) such members 16 are provided in equally spaced apart locations about the wear ring 11.

The indication members 16 are indication 17 inserts in the wear ring 11. That is achieved, by fitting the inserts 17 into holes 18 in the wear ring 11. Those holes 18 extend from an open end on one surface of the wear ring 11 , into the ring 11 , to a blind or closed end. In this embodiment, the inserts 17 are in the nature of plugs press fitted into the holes 18. Each plug insert 17 has a short cylindrical stem 19 located in hole 18 and a disc shaped head 20 at one end thereof overlying inner surface 12 of wear ring 11.

In one arrangement (as shown), the holes 18 extend from the inner surface 12 of the wear ring 11 toward the wear face 14. With this arrangement, the inserts 17 are initially hidden when viewing the wear face 14 but, as the wear face 14 wears through to the blind end of the holes 18, the inserts 17 become exposed. Initial exposure of the inserts 17 may represent the worn condition, with any subsequent wear of the wear ring 11 wearing away not only the inserts 17 but potentially also the wheel rim 6. That initial exposure may alternatively represent a wearing condition, so that subsequent wear of the wear ring 11 wears away the inserts 17 until the worn condition is reached.

In another arrangement (not shown), the holes 18 for the inserts 17 extend from the wear face 14 of the wear ring 11 toward the inner surface 12. With this arrangement, the inserts 17 are initially exposed when viewing the wear face 14, and progressively wear away together with the wear ring 11. Progressive wear of the wear inserts 17 may represent the wearing condition of the wear ring 11 , whilst the worn condition is represented by the inserts 17 having been completely worn away. With either arrangement, the inserts 17 may (as shown) all extend the same distance from the wear ring surface 12 or 13 into the wear ring 11 so that they will all provide the same wear condition indication. Alternatively (not shown), those inserts 17 may extend varying distances, with some of the inserts 17 providing an indication of the wearing condition and other inserts 17 providing

an indication of the worn condition of the wear ring 11. In this alternative arrangement, inserts 17 may be grouped around the wear ring 11 , with each insert group including individual inserts 17 extending different distances into the wear ring 11. To facilitate their observation in use, the indication inserts 17 have a characteristic that is in visible contrast to the surrounding wear ring 11 in which they are mounted. In this embodiment, that characteristic is colour, so that the inserts 17 are in a colour that contrasts with the wear ring 11. The inserts 17 are brightly coloured, in this embodiment. Where appropriate, differently coloured inserts 17 or inserts 17 with differently coloured sections may be provided to indicate different wear conditions when the particular colours are exposed.

In addition, or alternatively, the contrasting characteristic of the indication inserts 17 is material composition, so that the inserts 17 are composed of a different material to the wear ring. The inserts 17 are composed of plastic material for use with metal wear rings, in this embodiment. In this preferred embodiment, the inserts 17 are composed of brightly coloured plastic material.

The wear ring 11 is bonded onto the wheel rim 6 with a layer of damping material 21 there between. That damping material layer 21 is bonded to the inner surface 12 of the wear ring 11 and the outside 9 of the wheel rim 6. The damping material layer 21 is of thin section, and extends over the entire inner surface 12 of the wear ring 11.

In this embodiment, the damping material is the same material as that forming the tyre 7, i.e. rubber.

The tyre 7 is moulded onto the wheel rim 6 and, in this embodiment, the wear ring 11 is bonded into position during moulding of the tyre 7. The tyre 7 extends over part of the outer surface 13 of the wear ring 11 to enhance mounting. That is achieved by cross-sectionally curving the wear ring 11 as shown so that the wear ring 11 converges toward the disc periphery 5 and flange 4. In particular, an outer peripheral region of the wear ring extends inwardly of the tyre 7 toward the flange 4. In this way, the wear ring 11 is partially imbedded in the tyre 7, although the tyre material does not extend over the wear face 14 of the wear ring 11.

The wear ring 11 bonded to the wheel rim 6 with damping material layer 19 incorporates the above wear indication means 15. Where the indication

means 15 is indication inserts 17 fitting into holes 18 in the inner surface 12 of the wear ring 11 , then those inserts 17 will be held in position by the damping material bonding the wear ring 11 to the wheel rim 6.

Bonding of the wear ring 11 to the wheel rim 6 offers relatively cheap manufacture, as well as secure mounting of the ring 11. In addition, the provision of damping material between the ring 11 and wheel rim 6 provides potential noise and vibration damping to the vehicle body.

In use of the wear device 10 and road wheel 1 of the present invention, the wear face 14 of the wear ring 11 will progressively wear as a consequence of the abrasive engagement of the chain link horns. However, the extent of that wear can be easily monitored by periodic inspection of the wear rings 11. In this embodiment, an inspection that reveals one or more indication inserts 17 exposed through the wear face 14 will indicate that the wheel 1 needs replacing.

Timely replacement will avoid damaging wear to the wheel rim 6 and enable refurbishment of the wheel 1 for subsequent re-use.

Finally, it is to be understood that various alterations, modifications and/or additions may be made to the wear device and vehicle road wheel without departing from the ambit of the present invention as defined in the claims appended hereto.