AU716446B2

AU716446B2 - Steerable trolley and wheels

Info

Publication number: AU716446B2
Application number: AU70408/96A
Authority: AU
Inventors: Laurence De Bono
Original assignee: Metro Products & Co Pty Limite
Current assignee: Afm Engineering Pty Ltd; FAULKNER COLLINS Pty Ltd
Priority date: 1995-10-26
Filing date: 1996-10-25
Publication date: 2000-02-24
Anticipated expiration: 2016-10-25
Also published as: AU7040896A

Description

'/UU/Ul 28 /591 Regulation 3.2(2)

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT 8* 9* Application Number: Lodged: Invention Title: STEERABLE TROLLEY AND WHEELS The following statement is a full description of this invention, including the best method of performing it known to us STEERABLE TROLLEY AND WHEELS TECHNICAL FIELD The present invention relates to bearings, particularly but not exclusively for shopping trolley wheels, and to improved wheels and trolleys utilising such bearings.

BACKGROUND ART A commonly reported difficulty with conventional shopping trolleys relates to steering, particularly when a substantial load is in the trolley. Conventionally, all four wheels of the trolley are fitted with swivelling wheels. This makes the trolleys much easier to handle when nested, thereby facilitating collection procedures by the supermarket owner. However, when the trolleys are operated singly, having all four wheels swivelling increases the difficulty of steering.

One solution to this problem is to provide two wheels, generally at the 15 back, which can be locked. A wide range of mechanisms have been proposed e*.

to allow such locking in the prior art. These mechanisms involve levers and pivoting mechanical arrangements external to the trolley. Whilst these arrangements may well satisfactorily perform the task of releasably locking wheels, they create further difficulties. Further projections from adjacent the wheels are liable to be a cause of injury to shoppers. Such projections are also, because of their external positioning, subject to damaging in use. Indeed, such projections may also damage the shelving and other fixtures in the supermarket.

In general, they require a user to operate a special mechanism to lock or release the wheels. Similar issues arise for trolleys in other contexts than supermarkets.

It is accordingly an object of the present invention to provide an improved bearing arrangement, to allow for rotation when desired, but generally biased against into a rest position. It is a further object to provide an improved trolley wheel assembly, and a trolley which is more readily steerable.

SUMMARY OF INVENTION According to a first aspect, the present invention provides a wheel bearing adapted to allow relative motion between two components, said bearing comprising a shaft member and a body, said shaft being received within said body, said shaft including on an outer surface thereof received within the body a first shaped groove, and said shell including on an inner surface thereof a second shaped groove, said first and second grooves operatively cooperating to receive a plurality of ball bearings, said grooves being shaped to provide at least one rest position, and that upon rotation of the shaft relative to the body from the or a rest position, the shaft moves axially away from the body to allow the balls and grooves to move through one or more intermediate positions between the rest positions, the load on said shaft biasing the bearing to return to one of said rest positions.

Preferably, the grooves are continuous, and are shaped to provide lowered and raised points. Preferably, the grooves are shaped in substantially the same shape, so as to provide between them a track for the balls. When the balls rest in the lowered part of the shaft groove and the lowered part of the shell 15 groove, the shaft is then received to its full extent within the shell. This defines the relatively stable, rest positions. If sufficient load is applied to the bearing, in the supermarket trolley application by an attempt to turn the trolley, then the grooves mutually rotat6 so that the balls hold the shaft at a position between the rest positions, and by virtue of the shaping of the grooves, this forces the shaft axially outward from the shell. This in turn creates a load downwards toward the shell, which tends to urge the bearing into one of its rest positions. Thus, an arrangement is created in which although certain positions are preferred, the wheels may be rotated through other positions to facilitate movement in a nesting situation, or when required for steering.

For use with a shopping trolley, the axial shaft would normally be affixed to the base or frame of the trolley; the shell is received within a housing connected to the trolley wheel. Of course, an implementation is possible where the shell is attached to the frame, and the shaft to the wheel, although this is not preferred. In a preferred implementation for a trolley, the front wheels are conventional swivel wheels, and the rear wheels are wheels incorporating a bearing according to the present invention, with the rest position defined as parallel to the trolley frame. For most normal use by shoppers, the arrangement whereby the back wheels are fixed and the front two free to move, allows for optimal ease of use. If a particularly sharp turn manoeuvre is required, sufficient turning force will cause the rear wheels to move to an intermediate position and allow the rear wheels to turn. It is important to note that the nature of the bearing is such that it is more difficult to move to an intermediate position when the trolley is heavily loaded. This further increases the inherent stability of the arrangement. In the non-loaded situation, and more particularly when trolleys are required to be collected and moved to a dispensing point, if the trolleys are unloaded it is relatively easier for the rear wheels to be moved to a swivel position.

It will be appreciated that the inventive bearing is applicable to other caster wheel type systems and the shopping trolley case is provided only by way of example.

BRIEF DESCRIPTION OF DRAWINGS 15 A preferred implementation of the present invention will now be described with reference to the accompanying figures, in which: figure 1 is a sectional view of a preferred bearing arrangement according to the present invention; figure 2 is a view showing an outline of the ball tracks in the inner shell 20 and shaft; figure 3 illustrates the shape of the base shell; figure 4 illustrates the shape of the shaft.

DESCRIPTION

.:Referring to figure 1, the general arrangement of a bearing according to the present invention suitable for shopping trolleys can be seen. It is emphasised that various embodiments are possible within the general scope of the present invention. The present version is presented purely by way of example.

Referring to figure 1, the bearing in general comprises a shaft member 2, a lower shell 1, two sets of balls 4,6 and an end cap 3. The upper set of balls 4 is provided so as to allow for smooth axial movement and rotation, to prevent the slewing of the shaft within the shell.

Referring to figure 2, it can be seen that the track 5 (shown in dotted outline for balls 4 is essentially circular, with its axis corresponding to the axis of shaft 2. The balls are entirely carried within the shaft there is no corresponding groove on the shell in this implementation, although if desired such could be provided.

Lower groove 7 contains balls 6. However, lower groove 7 only contains a complete track when mated with groove 8 in shell 1. As can be seen from figure 2, and figure 4, groove 7 is shaped so as to have a generally circular plan, but with dips 10 (the other side is of course not visible)on either side of peaks 11. Similarly, shell 1, referring to figure 3, has a shaped groove in the base, having peaks 12 and dip 13. It will be appreciated that if the view was rotated 900, a peak would be central, and the grooves would appear to either side. If 'these grooves are relatively aligned, so that dips 10 and 13 are aligned, then the shaft is in its fully inserted or rest position, shown in figure 1. In figure 2, 15 however, it can be seen that the shaft is raised somewhat, and indeed to its full extent, relative to shell 1. In this position, the peaks and dips of the grooves 8 and 7 are out of alignment, so that the shaft is lifted from the shell.

It can be seen that this arrangement serves to provide a generally stable rest position, with the possibility of swivelling out of the rest position only if sufficient turning force is provided to the bearing. Moreover, the greater the load from the shaft 9 on the bearing, the more difficult it will be to move from this rest position, as mutual movement of the shaft and shell requires one to lift relative to the other.

It will be appreciated that alternative shapes could be used for the mating grooves however, trial and error has indicated the shape shown as preferred.

In a preferred use of the inventive bearing, a shopping trolley wheel is fitted with such, so that shaft 9 is fixed to the trolley base or frame, and shell 1 is received in a recess associated with a wheel assembly. The fixtures may be entirely conventional, apart from the bearing. Of course, the reverse arrangement with the shaft member attached to the wheel and the shell to the frame is possible, with suitable engineering modifications, but is not preferred.

Preferably, two wheels according to the present invention are mounted on the rear of a shopping trolley, and two conventional swivel wheels are mounted on the front, to provide a more readily steerable trolley which nonetheless allows for swivelling action during collection and nesting procedures. Of course, this arrangement may be applied to goods trolleys, luggage trolleys, and similar devices.

The reader will appreciate that variations and additions are possible within the spirit and scope of the invention.

*oe• ee**

Claims

1. A wheel bearing adapted to allow relative motion between two components, said bearing including a shaft member and a body, said shaft member being received within said body, said shaft member including on an outer surface thereof received within the body a first shaped groove, and said body including on an inner surface thereof a second shaped groove, said first and second grooves operatively cooperating to receive a plurality of ball elements, said grooves being shaped to provide at least one rest position, and that upon rotation of the shaft member relative to the body from the or a rest position, the shaft member moves axially away from the body to allow the ball elements and grooves to move through one or more intermediate positions between the rest positions, the load on said shaft member biasing the bearing to return to one of said rest positions. e• *o

2. A wheel bearing according to claim 1, wherein said first and second grooves are continuous, and are shaped to provide lowered and raised points relative to the axis of the shaft member. S

3. A wheel bearing according to claim 2, wherein the first and second grooves are shaped in complementary shapes, so as to provide between them a track for the ball S: elements. S.

4. A wheel bearing according to claim 3, wherein upon rotation from the rest position, the shaft member and body move axially away from each other, so as to provide said biasing operatively by the axial load across said bearing.

A wheel bearing according to any one of the preceding claims, wherein said bearing further includes a third groove in said shaft member or said body and a plurality of second ball elements, said third groove being axially displaced from said other grooves, so as to stabilise said bearing.

6. A wheel assembly, including a wheel, means for connecting the wheel to a structure, and a bearing, said bearing including a shaft and a body, said shaft being received within said body, said shaft being connected to said means for connecting, and said body being connected to said wheel, said shaft including on an outer surface thereof received within the body a first shaped groove, and said body including on an inner surface thereof a second shaped groove, said first and second grooves operatively cooperating to receive a plurality of ball elements, said grooves being shaped to provide at least one rest position, and that upon rotation of the shaft relative to the body from the or a rest position, the shaft moves axially away from the body to allow the ball elements and grooves to move through one or more intermediate positions between the rest positions, the load on said shaft biasing the bearing to return to one of said rest positions.

7. A wheel assembly according to claim 6, wherein said first and second grooves 600° are continuous, and are shaped to provide lowered and raised points relative to the axis of the shaft.

8 A wheel assembly according to claim 7, wherein the first and second grooves are shaped in complementary shapes, so as to provide between them a track for the S ball elements. S

9. A wheel assembly according to claim 8, wherein upon rotation from the rest to o: position, the shaft and body move axially away from each other, so as to provide said biasing operatively by the axial load across said bearing.

A wheel assembly according to any one of claims 6 to 9, wherein said bearing further includes a third groove in said shaft or said body and a plurality of second ball elements, said third groove being axially displaced from said other grooves, so as to stabilise said bearing. 8

11. A shopping trolley, characterised in that said trolley includes at least two wheel assemblies according to any one of claims 6 to

12. A shopping trolley according to claim 11, wherein said trolley has two front wheels adapted to swivel freely, and two rear wheel assemblies according to any one of claims 6 to

13. A shopping trolley according to claim 12, wherein the rear wheels are biased to travel parallel to the direction of motion of the trolley.

14. A wheel bearing substantially as described with reference to figures 1 to 4. DATED this 22n d day of December 1999 METRO PRODUCTS CO PTY LTD B B B B. WATERMARK PATENT TRADEMARK ATTORNEYS 290 BURWOOD ROAD HAWTHORN VICTORIA 3122 AUSTRALIA PNF:MP:CA P12946AUOO