IMPROVEMENTS RELATING TO VEHICLE WHEELS

Abstract: A vehicle wheel attachment offers an increased tread to support the vehicle on soft ground. A drum-like body (6) is held against the wheel (1, 2) by a co-axial anchorage device (4, 5, 8, 9) secured to the wheel using the existing wheel studs. The normal nuts are permanently replaced by special ones (10, 19, 22) which provide slots (13), screw threads (17, 20, 23) or other means by which an anchorage member (4) can be easily secured and removed without disturbing those nuts. A rod (5) from the anchorage member to the outer end of the drum, to receive the clamping means (9), is mounted, or has the ability, to flex within a limited cone. The drum (6) may have a ribbed tread (40) and provision can be made for further pieces to fit the valleys (41) and thereby alter the tread.

Description: "Improvements relating to ' Vehicle ' Wheels" This invention relates to vehicle wheels. It is concerned with lateral attachments which can increase the traction and buoyancy of a normal wheel, such as those of tractors and other cross-country vehicles. It is a development of that described in GB-2028239B. In that earlier patent there is described a drum-like body which is held to the outside of a wheel by an internal anchorage secured, preferably, to the studs on which the wheel itself is mounted. It was also suggested that there could be separate anchorage points, but not all wheels could conveniently be so adapted. In the preferred arrangement, the existing nuts were removed, the anchorage member placed over the studs and the same nuts were replaced on the tips of the projecting studs. Practice has proved that this is unsound in most cases. Wheel studs tend to be just long enough to accept a single nut and do not normally project proud of the nut. Also, the inner ends of the wheel nuts are generally coned to fit corresponding recesses around the apertures in the wheel. An anchorage member for a wheel extension has to be substantial, and the flange with apertures or slots which fit over the studs needs to be thick. This means that it occupies quite a length of stud, reducing that available to the nut, particularly if it is a simple flat flange without a dimpled configuration to fit the recesses and accept the coned ends of the nuts. Thus the full capacity of the nuts is not used and the securing of the anchorage member, and indeed of the wheel itself, is weakened. It has also been found unacceptable to leave the anchorage member in place after removing the drum and the centre bolt. Inevitably, it projects quite a way, and is a considerable hazard. Therefore whenever the drum is removed, the anchorage member is taken off as well, which means removing and replacing the wheel nuts. If all the studs are used, this means jacking up the vehicle, while if only some of them are employed there is less security for the anchorage member. In some cases, the hub and stud configuration may compel use of all the studs. In any event, apart from being quite a lengthy and tedious operation, repeated fitting and removal of a heavy metal anchorage member can easily damage the threading of the studs, making them useless. Another drawback with the original attachment was that, being made of metal, it was rigid and unyielding and prone to permanent damage if driven over rough ground where rocks made severe impacts. It is the aim of this invention to provide a safer anchorage for such a wheel attachment, one that will be easier and quicker to fit and remove, and which, preferably, will have some resilience. According to one aspect of the present invention there is provided a nut for a vehicle wheel comprising an internal threaded section for engagement with a stud and an axial extension to project proud of the wheel hub and providing means for attachment of a secondary, co-axial wheel anchorage member. In one preferred form the axial extension is a stud with a " shoulder at its base to locate the anchorage member. This may have a detent to receive a pin which makes the anchorage member captive. Alternatively, the nut can be externally screw-threaded to receive a further nut which makes the anchorage member captive, or it may have an internal threaded socket to receive a bolt. In the latter case, the wheel nut may have a con¬ tinuous screw threaded passage whose outer end portion forms the socket. According to another aspect of the present invention there is provided an anchorage device for attaching a secondary wheel co-axially to a primary wheel, comprising a member for fixing to the hub of the primary wheel using existing studs and a substantially rigid rod with one end secured centrally to said member to extend co- axially of the secondary wheel and provide means at its other end for retaining that wheel against the primary wheel, the rod being capable of flex¬ ing within a limited cone whose apex is at the inner end of said member. The rod may be clamped to the member with the intermediary of resilent means, such as a rubber block or spring on the inside of said member, or a rubber bush encircling the rod as it passes through said member. The bush passage may be shaped to diverge in the inward direction and to receive a corresponding formation on the inner end of the rod. The external profile of the bush may also be generally divergent in the inward direction and seat in a matching aperture in said member. Alternatively, the inner end of the rod may be fixed to said member, and the rod itself would then flex. This may be achieved by making the rod in rigid sections joined by one or more flexible sections. According to a further aspect of the present invention there is provided a ribbed wheel attachment securable to the side of a vehicle wheel by a clamping member at its outer end and a plurality of filler elements for fitting in the valleys between the ribs, the attachment having webs across the inner ends of the valleys with detents to receive matching projections on the inner ends of said elements, and the outer periphery of said clamping member trapping and retaining the outer ends of said elements. The invention also embodies any combination of these features. For a better understanding of the invention, some embodiments will now be described, by way of example, with reference to the accompanying drawings, in which: 5 Figure 1 is a cut-away perspective view of an attachment for giving soft ground support and traction fitted to a pneumatic tyred wheel. Figure 2 shows examples, in axial section, of replacement wheel nuts for use in securing an 10 anchorage member for such an attachment. Figure 3 shows details, in axial section, of alternative anchorage members, and Figure 4 is a diagrammatic perspective view of part of a wheel attachment with elements for l ~ modifying the tread pattern. In Figure 1, a wheel 1 has a pneumatic tyre 2 fitted in the usual way in a tyre channel between outer rims. The wheel is secured by nuts on studs projecting through an annular array of apertures in its 20 hub 3. As in GB-2028239B some, at least, of these studs are used to fit an anchorage member 4 from which a rod 5 extends co-axially with the wheel. A ribbed drum-like body 6 fits over this assembly, its open inner end engaging either the outer rim of the wheel 1 25 or, as in this example, the outer rim of an annular extension plate 7 whose inner rim closely fits the wheel rim. The drum has an outer end closed by a disc 8, which has a central hole to accept the outer end of the rod 5. A nut 9 is threaded on this exposed end and is tightened down to clamp the drum 6 co-axially to the wheel. Alternative fasteners, such as a snap- action cam device, may be used instead. The drum is preferably made in tough plastics material such as cross-linked polyethylene, and may be made by rotational casting, vacuum forming or injection moulding. Its thickness will normally be of the order of 8mm, it will be slightly coned, and there will be no inturned rim or formation at the inner end, so that similar drums can nest within one another. The disc 8 spreads the load and may be incorporated during the moulding process, attached later, or even be loose when the nut 9 is removed and locate in the rim of an aperture in the end of the drum. Referring now to Figure 2, there are shown details of how the anchorage member 4 can be secured. In each case, the normal wheel nut is removed and replaced by a special nut. In Figure 2(a), the special nut 10 has a closed outer end reduced in diameter to provide a shoulder 11 and a stud 12, the latter having a through slot 13 to receive a pin 14. The anchorage member 4 ' has an aperture. 15, or a recess open to its outer edge, which fits closely over this stud 12. It is then secured by the pin 14, which is shown as being of R formation and held captive by a lanyard 16 to the anchorage member. However, various other types of pin may be preferred, for example one that is held loosely to the stud 12 itself and which can be capsized and adjusted to make the anchorage member captive once it has been placed in position. An alternative arrangement in Figure 2(b) , follows the same general outline as Figure 2(a) , but here the extension stud 17 is threaded, and the anchorage member 4 is secured by a nut 18. In Figure 2(c), the special nut 19 is an elongated version of a normal wheel nut so that, when fitted, it leaves a threaded socket 20. The anchorage member 4 placed over this is secured by a bolt 21 engaged in the socket 20. Although the nut 19 is illustrated as having a through passage, screwthreaded along its entire length, it could be solid at its mid-length, with blind threaded sockets to fit over wheel studs and to receive the bolt 21. In a further version, shown in Figure 2(d), the special nut 22 has a solid outer end portion 23 externally threaded. This receives a cap nut 24 which is permanently captive to the anchorage member 4 but which is rotatable from the outside by a bolt head 25. It will be appreciated that these examples are not exhaustive and that the general concept is to replace the existing nut with a longer version which remains permanently in place and which has means on its outer end for making secure to the anchorage member 4. Where screw-threading is employed as in Figures 2 (b) , (c) and (d) , protective caps or plugs, conveniently of plastics material, may be fitted when the anchorage member is removed. As mentioned previously, it is desirable to allow the rod 5 to be deflected, at least to a limited extent, when the drum is distorted. Figure 3 shows various arrangements. In.Figure 3(a), the inner end of the rod 5 has a collar 26, which abuts the outside of the anchorage member 4 and then extends freely through an aperture 27 to the inside where it carries a rubber block 28 secured by a nut 29 with the intermediary of a plate 30. The rubber is very firm and dense and will sustain the axial loading imposed when the drum is tightened to the wheel. But even after this compression, it will still be able to distort to a certain extent to allow the rod 5 to shift within a narrow cone as indicated by the broken lines. A similar effect can be obtained by a coil spring 31 as shown in Figure 3(b). In another embodiment (Figure 3(c)) the aperture in the anchorage member 4 is enlarged to receive a solid rubber bush 32 which firmly encloses the inner end of the rod 5. The rod is retained by an enlarged washer or plate 33, spanning the bush on the inside of the anchorage member with its rim abutting solid metal, and a nut 34. This will also allow limited deflection of the rod 5, while maintaining it securely captive.. Figure 3 (d) shows another version using a firm rubber block 35. Its central passage opens out on the inside into a belled socket 36, which receives a correspondingly shaped formation 37 at the inner end of the rod 5. This may be an integral formation on the rod or be a fitting on it. It acts as a keep for the rod, but allows deflection as with previous embodiments. Another approach is shown in Figure 3(e), where the inner end of the rod 5 is rigidly secured to the anchorage member 4, as by welding or a screw thread and nuts. The rod 5 is not, however, continuous, it is divided.into two parts inextensibly connected by a sleeve 38 which is capable of limited flexure. Again, there can be many other arrangements, and the rod 5 itself may simply be made of a material that can flex but not stretch to any significant extent. Indeed, it could be a chain, as described in the earlier patent. However, when the drum is offered up to the wheel, the fitter has to "find" the rod or other connection to the anchorage member to guide it through the hole in the disc 8. With something flexible like a chain, the outer end would have to be recovered, for example by tying on a lead string first and then pulling it through the disc hole. With the arrangement described, although the rod 5 might sag slightly, its outer end will generally register approximately with the hole in the end of the dome as the latter is offered up, and can be "fished out" with a finger. As a further refinement, the rod 5 may incorporate a shock absorber. In all these arrangements, the rod 5 will be secured against rotation when the nut 9 is tightened. Each drum will be made with a fixed tread pattern which may be suitable for some terrains but not for others. To adapt, it is of course possible to change the drums, using the same anchorages. However, rather than carrying spare sets of drums. there could be fittings to modify the tread pattern of a basic set of drums. An example is shown in Figure 4. The basic drum 39 here has prominent ribs 40 and deep valleys 41 between them. At the inner end of the drum, they merge into a rim 42 which provides closed ends for the valleys 41. These ends are formed with indents or recesses 43. Filler pieces 44 are moulded to have a snug fit in the valleys 41, leaving the peaks of the adjacent ribs 40 proud. The inner end of each piece 44 has a lug 45 which engages any recess 43, while its outer end has a tongue .6 which curves around the outer end of the drum and terminates within the outer diameter of the disc 8. This is of the "loose" variety or one which can be fastened after moulding. When all such filler pieces 44 are in place, when the disc 8 is replaced, it traps all the tongues 45 and thereby secures those filler pieces. The drum is thereby converted into one with a shallow tread. The filler pieces 44 themselves may have ribs or studs, effectively to add to the ribs 40. In a further arrangement, the filler pieces 44 are flush with the ribs 40. Traction can then be provided by fitting a net or skeletal envelope over the drum, this being clamped between the rim and the wheel at the inner end and by the disc 8 at the outer end. There are some wheels and hubs which are mutually attached by bolts fitted from the outside through holes in the wheels and into threaded sockets in the hub. It will be understood that where reference has been made to special nuts for fitting studs, there could, for this type of mounting, be replacement bolts with special heads, and the claims should be construed accordingly. While the primary aim is to provide extra flotation and traction, the principles described above can be applied to attaching a winch drum to a driven wheel of the vehicle.

Claims: ' CLAIMS 1. A nut for a vehicle wheel comprising an internal threaded section for engagement with a stud, and an axial extension to project proud of the wheel hub and providing means for attachment of a secondary, co-axial wheel anchorage member. 2. A nut as claimed in Claim 1, wherein the co-axial extension is a stud with a shoulder at its base to 'provide location for said anchorage member. 3. A nut as claimed in Claim 2, wherein the stud has a detent to receive a pin which makes the anchorage member captive. 4. A nut as claimed in Claim 1, 2 or 3, wherein the nut is externally screw-threaded to receive a further nut which makes the anchorage member captive. 5. A nut as claimed in Claim 1, wherein the axial extension has a socket internally threaded to receive a bolt which makes the anchorage member captive. 6. A nut as claimed in Claim 5, wherein the nut has a continuous screw-threaded passage whose outer end portion forms the socket. 7. An anchorage device for attaching a secondary wheel co-axially to a primary wheel, comprising a member for fixing to the hub of the 5 primary wheel using existing studs and a substan¬ tially rigid rod with one end secured centrally to said member to extend co-axially of the secondary wheel and provide means at its other end for retaining that wheel against the primary wheel, the rod being iO capable of flexing within a limited cone whose apex is at the inner end of said member. 8. A device as claimed in Claim 7, wherein the rod is clamped to said member with the intermediary of resilient means. -5 9. A device as claimed in Claim 8, wherein the resilient means is a rubber block on the inside of said member. 10. A device as claimed in Claim 8, wherein the resilient means is a spring on the inside of said 20 member. 11. A device as claimed in Claim 8, wherein the resilient means is a rubber bush encircling the rod as it passes through said member. 12. A device as claimed in Claim 11, wherein 25 the bush passage is shaped to diverge in the inward direction and to receive a corresponding formation on the inner end of the rod. 13. A device as claimed in Claim 11 or 12, wherein the internal profile of the bush is generally divergent of the inward direction and seats in a matching aperture of said member. 14. A device as claimed in Claim 7, wherein the inner end of the rod is fixed to said member and the rod itself can flex. 15. A device as claimed in Claim 14, wherein the rod has rigid sections joined by flexible sections. 16. A ribbed wheel attachment securable to the side of a vehicle wheel by a clamping member at its outer end and a plurality of filler elements for fitting in the valleys between the ribs, the attachment having webs across the inner ends of the valleys with detents to receive matching projections on the inner ends of said elements, and the outer periphery of said clamping member trapping and retaining the outer ends of said elements. 17. A ribbed wheel attachment securable to the side of a vehicle wheel using nuts each as claimed in any one of Claims 1 to 6, and/or an anchorage device as claimed in any one of Claims 7 to 15. 18. A ribbed wheel attachment as claimed in Claims 16 and 17.

Inventors: SNELL THOMAS BARTLETT, SNELL, THOMAS, BARTLETT
Applicants: SNELL THOMAS BARTLETT, SNELL, THOMAS, BARTLETT
Application year: 1987
Main classification: B60B3
IPC codes: B60B3, B60B15, F16B35, F16B37