GB2184071A - Attaching auxiliary wheels to tractor wheels - Google Patents

Abstract

The auxiliary wheel 3 is attached to the tractor wheel 25 by a bayonet coupling 19, 23 and locking members 9. Studs 21 on the coupling portion 19 engage slots in the coupling portion 23 and the free ends of arms 17 of the locking members align with lugs 31 on the rim 33 of the wheel 25. A shaft 15 is then screwed into a hub 7 causing a flange 13 to rotate the members 9 about their pivots so that the ends of the arms 17 grip the lugs. <IMAGE>

Description

SPECIFICATION Improvements relating to tractor wheels The present invention relates to a tractor -wheel for use in a twin-wheel conversion.

When a tractor is to be used on steep land and/or rough grass land, it is advantageous for an extra rear wheel to be provided on each side of the tractor to provide for extra stability and grip. As a tractor will be required to be operational on varying types of terrain and extra rear wheels will not always be re quired, such extra rear wheels are usually detachably mounted coaxially with the permanent rear wheels on the tractor.

One known type of rear tractor wheel which is detachably mounted coaxially on a perma nent tractor wheel, comprises an outer annular rim on which a tyre is mounted, with a num ber of elongage spoke members welded to the rim at circumferentially spaced apart locations, each spoke member extending radially inwardly of the rim and being welded to a central hub through which a threaded bore ex tends axially of the wheel. A generally L shaped locking member is pivotally mounted on each spoke member, the locking member having a shorter arm and a longer arm, the junction therebetween being pivotably mounted on a spoke member adjacent to the outer annular rim of the wheel.

The longer arms extend generally radially of the wheel and the free end region of each longer arm pivotally engages against an annu lar flange fixedly mounted on one end of a threaded shaft which is screw-threadedly en gaged in the threaded bore in the central hub.

Thus, rotation of the threaded shaft by a handle or other suitable tool causes the annu lar flange to move axially of the wheel relative to the central hub, resulting in the L-shaped locking members being tilted so that the free end region of the shorter arm of each locking member moves generally radially outwardly with respect to the wheel. These free end regions of the said shorter arms have radially extending projections which, when a wheel is being mounted on a permanent tractor wheel, are first located radially inwardly of respective hollow lugs provided on the rim of said per manent wheel. Then, by rotating the threaded shaft the said radially extending projections are forced into the lugs against the rim of the permanent wheel to secure the wheels to gether, ready for use.

With the above type of twin wheel conversion it is often difficult to accurately locate the relatively heavy extra wheel so that all of the said shorter arms engage into the respective lugs on the permanent wheel. Further, when in use, torque can be applied to an extra wheel and not the permanent wheel to which it is attached, which torque, if sufficient, can result in the shorter arms being disengaged from within the said lugs. The extra wheel can then completely disengage from the permanent wheel. This usually occurs on rough terrain where the wheel cannot be readily remounted.

To combat this problem it is known to tighten the threaded shaft as much as is possible.

However, this can and does lead to the threads being stripped.

It is the aim of the present invention to provide a wheel of the above-mentioned type which is more easily installable on a permanent wheel and which is positively retained against inadvertent detachment.

According to the present invention there is provided a wheel of the afore-mentioned type, comprising a locating and gripping means fixedly mounted on said central hub, said locating and gripping means being adapted to be lockably engageable with complimentary means provided on a permanent wheel.

In a preferred embodiment of the present invention said complimentary means comprises a hollow cylindrical member which is fixedly mounted on the central hub of a permanent wheel on a tractor, coaxially therewith. The cylindrical member has two slots formed in its side wall, which slots form part of a bayonet connection. The other part of the bayonet connection is formed as a pair of laterally projecting studs provided on a further cylindrical member which can be axially engaged within said hollow cylindrical member, with said projections following the line of said slots. Said further cylindrical member and said projecting studs together form said locating and gripping means, the cylindrical member, in use, being securely attached, e.g. bolted or welded, on said central hub of the extra wheel.Thus, to install the wheel of the present invention on a permanent wheel, the said cylindrical member of the locating and gripping means is first engaged in the hollow cylindrical member of said complimentary means, the slots in said complimentary means being so located that when the slots and respective projecting studs are aligned with each other, the shorter arms of the L-shaped locking members are located just to one side of the respective associated lugs on the permanent wheel. As the wheel is moved axially the studs move along the slots, each slot initially extending axially and then generally circumferentially of the hollow cylindrical member.Thus the wheel has to be subsequently rotated relative to the permanent wheel, the shorter arms of the locking members being each positioned radially inwardly of a respective lug on said permament wheel when the studs engage the closed ends of the slots. By then rotating the threaded shaft, the shorter arms engage in the respective lugs so that the wheel is thus held on the permament wheel both by the bayonet connection, and by the engagement of said shorter arms within said lugs. Preferably a pin is also engaged through aligned bores in the said cylindrical members, the bores extending generally transverse to the axes of said cylindrical members; this pin positively locking the wheels together and preventing inadvertent separation.

In an alternative embodiment, the cylindrical member and studs form the locating and gripping means secured to the central hub of the permanent wheel and the hollow cylindrical member is secured to the hub of the extra wheel.

As an alternative to the bayonet connection described hereabove any other suitable locking and rotatable interconnection may be substituted.

The present invention thus makes it easier to locate and accurately install extra wheels on permanent wheels, besides providing for a positive lock therebetween.

The present invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a front view of part of a preferred embodiment of wheel constructed according to the present invention; Figure 2 is a sectional view taken along line I-I in Fig. 1; and Figure 3 is an exploded view illustrating the bayonet connection used in the preferred embodiment of Fig. 1.

The preferred embodiment of the present invention illustrated in the accompanying drawings comprises an annular outer rim 1 on which a tyre 3 is mounted. Elongate spoke members 5 are welded to the rim 1 in adjacent pairs, at circumferentially spaced-apart locations, each spoke member 5 extending generally radially of the wheel and being welded to a central hub 7 through which a threaded bore 8 extends axially of the wheel.

Pivotally mounted between each pair of spoke members 5, adjacent to the rim 1, is a generally L-shaped locking member 9, the free end region of the longer arm 11 of each locking member 9 being pivotally engaged with an annular flange 13 provided on one end of a threaded shaft 15. The threaded shaft 1 5 screw-threadedly engages in the complimentarily threaded bore 8 in the central hub 7.

Thus, rotation of the threaded shaft 15 moves the annular flange 13 axially of the wheel, towards or away from said central hub 7. When the annular flange 13 is moved towards said central hub 7 the locking members 9 pivot causing the free end regions of the shorter arms 17 of the locking members 9 to move generally radially outwardly with respect to the wheel.

Welded or otherwise fixedly mounted on said central hub 7 are locating and gripping means in the form of a cylindrical member 19 having a pair of laterally projecting studs 21.

This cylindrical member 19 and studs 21 form part of a bayonet connection, the other part being formed by a hollow cylindrical member 23 which is bolted onto the hub of a permanent tractor wheel 25, coaxially therewith.

This hollow cylindrical member 23 has a pair of diametrically opposed, initially tapered, slots cut in its wall. Part 27 of each slot extends generally axially of the hollow cylindrical member 23 and part 29 extends generally circumferentially.

In use the cylindrical member 19 is engaged in the hollow cylindrical member 23 and the wheel is rotated to align each stud 21 with the open end of the axially extending part 27 of a slot. In this position the free end regions of said shorter arms 17 of the locking members 9 are each located circumferentially to one side of a hollow lug 31 provided on the radially inner surface of the rim 33 of the permanent wheel.

As the wheel is moved axially towards the permanent wheel the studs 21 move along the axial part 27 of each slot and the free end regions of the shorter arms 17 move to a position axially in line with the lugs 31 on the rim 33 of the permanent wheel. Subsequently the wheel is rotated to allow the studs 21 to move along the circumferentially extending part 29 of the slots, the free end regions of the shorter arms 17 then moving to a position directly opposite the lugs 31. In this position the threaded shaft 15 is rotated by using the handle 34 on the end 32 of the shaft 15, to cause the free end regions of the shorter arms 17 to engage and grip the respective lugs 31.

This frictional engagement with the rim 33 and the provision of the lugs 31 holds the two wheels together, the bayonet connection 19,21; 23,27,29 aiding the location and retention of the extra wheel. To prevent any possibility of the extra wheel rotating relative to the permament wheel and becoming detached, a pin 35 is engaged through aligned bores 37,39 in the cylindrical member 19 and hollow cylindrical member 23, these aligned bores 37,39 extending transversely to the axes of said cylindrical members 19,23. To detach the extra wheel the pin 35 must therefore be first removed. Then the threaded shaft 15 can be slackened to release the said shorter arms 1 7 from the lugs 32, and the extra wheel rotated and moved axially to release the bayonet connection 19,21; 23,27,29.

In an alternative embodiment the hollow cylindrical member 23 is fixed to the central hub 13 and said cylindrical member 19 is bolted to the hub of the permanent wheel.

Instead of the bayonet connection 19,21; 23,27,29 some other suitable inter-engaging locking means can of course be substituted.

The present invention thus provides a wheel which can be relatively easily installed as a twin-wheel conversion for a tractor, the wheel being positively locked in position, preventing accidental detachment.

Claims (9)

1. A wheel comprising a central hub and an outer rim, with locating and gripping means fixedly mounted on the central hub, said locating and gripping means being adapted to be lockably engageable with complimentary means provided on a further wheel.

2. A wheel comprising an outer rim connected to a central hub by a number of elongate spoke members, a number of generally Lshaped locking members being pivotally mounted on the spoke members adjacent to the said outer rim, one arm of each generally L-shaped locking member extending generally radially of the wheel and engaging against an annular flange fixedly provided on a threaded shaft which is screw-threadedly engaged in a threaded bore in said central hub, the other arm of each generally L-shaped locking member being engageable with a further wheel to hold said wheels together, locating and gripping means fixedly mounted on said central hub, coaxially therewith, being also lockably engageable with complimentary means provided on said further wheel.

3. A wheel as claimed in claim 1 or claim 2, in which said locating and gripping means is formed by a pair of laterally projecting studs provided on a cylindrical member.

4. A wheel as claimed in claim 3, in combination with said further wheel, in which said complimentary means comprises a hollow cylindrical member fixedly mounted on the central hub of said further wheel, coaxially therewith, said hollow cylindrical member having two slots formed in its side wall, into which said studs engage when said cylindrical member is axially engaged in said hollow cylindrical member.

5. A wheel as claimed in claim 1 or claim 2, in which said locating and gripping means comprises a hollow cylindrical member having two slots formed in its side wall, said hollow cylindrical member being mounted on said central hub coaxially with said wheel.

6. A wheel as claimed in claim 4, in combination with said further wheel, in which said complimentary means is formed by a pair of laterally projecting studs provided on a cylindrical member, said studs engaging in said slots when said cylindrical member is axially engaged in said hollow cylindrical member.

7. A wheel as claimed in any one of claims 4 to 6, in which said slots each have a portion which extends generally axially of the hollow cylindrical member, and a portion which extends generally circumferentially of said hollow cylindrical member.

8. A wheel combination as claimed in claim 4 or 6, in which a pin extends through aligned bores in said cylindrical members.

9. A wheel constructed and arranged substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawings.