GB2363324A

GB2363324A - Castor wheel assembly with direction priority bearings

Info

Publication number: GB2363324A
Application number: GB0028090A
Authority: GB
Inventors: John Leslie Blackford
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-11-18
Filing date: 2000-11-18
Publication date: 2001-12-19
Anticipated expiration: 2020-11-18
Also published as: GB2363324B; GB0028090D0

Abstract

A castor wheel assembly comprises wheel 1, rotating on axle 2 about a forked support 3. Swivel axle 7 projects vertically from support 3 and is journalled in mounting 9 via plain bearing 8. Shaft 7 is spring biased via spring 11 and stop means 13. Axle 7 also passes through lower direction bearing 4, which is attached to and rotatable with fork 3 and upper direction bearing 5, which is attached to mounting 9. The two direction bearings have complementary camming surfaces such that swivelling of fork 3 and therefore direction bearing 4 causes the fork to be pushed vertically downwards, compressing spring 11. The restoring force exerted by the spring pulls bearing 4 upwards and causes fork 3 to swivel back to its original alignment. In use the castor assembly is fitted to for example a supermarket trolley and allows straight line motion of the trolley regardless of any slope it may be on. It is stated that two such assemblies are sufficient for this purpose provided that they are mounted diagonally opposite one another. The assembly is stated to be retrofittable to most trolleys.

Description

2363324 J L BLACKFORD M.C.I.O.B.

9 ASPLEY COURT HATTON WARWICK CV35 7ED ++44(0)1926 495238 Tel/Fax.

VERSATILE CASTOR WHEEL ASSEMBLY WITH DIRECTION PRIORITY BEARINGS BACKGROUND OF THE INVENTION

Most people have experienced the firustration of trying to persuade the trolley they are pushing, deciding of its own accord to follow an entirely different track to the one chosen by them. It usually means the trolley is following the law of gravity and drifting down the slope they are trying to traverse. It usually needs a lot of muscle power to keep the trolley on the track required.

SUMMARY OF THE INVENTION

This new invention relates to a versatile castor wheel assembly which allows the user of the trolley to decide the track or line they want to go, with no regard to the sloping surface the trolley is on, knowing the trolley will stay exactly on that track or line without deviation, until required to change by the user, and then stay on the new track or line. This is achieved without the user applying excess muscle power just to keep the trolley on line. The only muscle power needed is to push the trolley in the direction required, just as normal, with all existing trolleys. The fabrication of this versatile castor wheel assembly can be carried out in metal, plastic, rubber, composite or a combination of any or all of these materials.

DESCRIPTION OF OPERATION (To be read in conjunction with detailed drawings I & 2

The preferred embodiment comprises a conventional castor wheel (1) revolving on a horizontal axle (2) supported by a forked axle support (3) which supports the axle on either side of the wheel. The top of this fork has a flat platfonn from which a vertical rod (the swivel axle)(7) protrudes fixed from the centre. If the alternative fixing is used, a bolt passes through the fork and screws directly into the trolley base allowing the castor fork to swivel around it. Fixed to the flat platform is a shaped bearing (4) (the lower) which acts as a direction priority interface. Preferably this bearing has a convex surface facing upwards with sloping shoulders. This shape runs linearly on plan from one side of the bearing to the other. This creates a ridge running from one side to the other. Preferably this lower bearing must be fixed to the flat platform so that the ridge is exactly the same line as the direction the castor wheel runs, which when fittedto a trolley correctly, makes the trolley travel in a straight line when pushed in a forward direction. The plan shape of the bearing can be round, I octagonal, square, rectangular or similar. Preferably this bearing interfaces with another (the upper) (5), of similar size but with opposite characteristics. The upper bearing has a groove making a concave surface with sloping sides which run from one side of the bearing to the other. Both the concave and convex surfaces of this pair of bearings are the same profile making a male and female interface, as detailed on drawing nurnber 1. The upper bearing is fixed to the body of the trolley (6) or object to be moved. Preferably the bearing is fixed with the groove running exactly in line with the direction in which the trolley is normally to be moved, which usually means directly fore and aft of the trolley parallel with the trolley linear axis. In a preferred embodiment a vertical swivel axle or bolt (7) passes through the two bearings (4) and (5), and allows the lower bearing (4) and castor wheel and fork (1) and (3) to swivel in a circular motion on plan a full 360. The vertical swivel axle above the direction priority bearings (4) and (5) passes through a housing (8) fixed to the trolley (9) or object to be moved. The housing which can be made of plastic, metal or other material has a hole through which the axle passes but with only sufficient clearance to allow the axle to swivel freely. This allows the castor wheel (1) in its supporting fork (3) to trace a circular motion on-plan. The vertical swivel axle is retained in its housing by the use of an adjusting nut (13) and a lock nut (14) on the top end of the axle above the housing. These nuts also retain a return spring (11) and spring compressor (12) which bear on the upper edge of the vertical swivel axle housing and are contained in the spring housing (10). (When the alternative fixing is used the bolt (7) as detailed on drawings 1 and 2, fixes directly to the trolley fi-ame (9) dispensing with the vertical swivel axle housing (8)). As the castor wheel fork (3) revolves onplan around the centre of the vertical swivel axle (7) the lower direction priority bearing (4) revolves with it. As the lower bearing revolves the upper shoulder starts to ride up the sloping surface of the upper bearing (5). The degree of how much this happens depends on how far off the original line the trolley has deviated. The degree of the angle of the interface contributes to the amount of the resistance the castor wheel has to being moved off line i.e. the forward direction the trolley is being pushed. The castor continually works up to and including the position where the lower and upper sections of the bearing are at right angles to each other at which point the trolley castor would be moving at 90' to the original line. The castor will continually perform throughout 360' circular travel. It will continually seek to nest the two bearings together which will be when the trolley is returned to being pushed or pulled in a straight line along the longitudinal axis of the trolley or object being moved. The return spring (11) encourages this to happen but not to the extent of overriding the demands of the trolley user. The castor will keep that line regardless of the slope until the user decides to change direction when the sequence will begin again.

When the alternative fixing is used the bolt (7) is fixed solid into the trolley frame (9) as detailed on drawings number 1 and 2. Although the vertical swivel axle housing is dispensed with the mechanism and action remain exactly the same. The direction priority bearing can also incorporate roller bearings as detailed on drawing number 1. Both the spring housing (10) and upper end of the swivel axle (7) including the adjusting nut (13) and lock nut (14) and the direction priority bearings (4) and (5) can be covered, if required, by housings (15) designed to be cosmetically more attractive and also to keep out dust and dirt from the mechanism. They can be made of metal, plastic, rubber or other materials or a combination of any or all of these materials. There are many variables which give this new invention great range and versatility. The material the bearings are made of can be plastic, metal, natural material or any 2 combination of any or all of these and can be designed according to the loading and usage the trolley is designed to take. The angle of the sloping shoulders of the bearing can be varied according to the needs of the trolley designer and loading potential. The loading and performance required of the bearings will have an influence on the plan size of the bearing.

To summarise, the performance of the bearing can be varied to suit many needs and demands by the use of specific materials, the angle of the shoulders and the size of the bearing or any combination of any or all of these variables.

3

Claims

1. A versatile direction priority castor wheel assembly which when fitted to a trolley as described in claim 4 or any other object to be moved by hand allows the trolley when pushed and used in the normal way not deviate from the users chosen path regardless of the slope or direction of slope the castor is being used on.

2. A versatile direction priority castor wheel assembly as claimed in claim 1, which should the user decide to deviate from the original given path, the castor will allow the change of direction without extra muscle power and will stay on the new chosen path or direction until the user changes direction again.

3. A versatile direction priority castor wheel assembly as claimed in claims I and 2 where direction priority bearings are used as described on drawing number I which are simple in design and cheap to manufacture making them competitive with alternatives.

4. A versatile direction priority castor wheel assembly as claimed in claims 1, 2 and 3 where only two versatile castors are needed per four wheel trolley and must be fixed on diagonal opposite comers of the trolley with the other two diagonal comers having normal castors.

5. A trolley according to claims 3 or 4, wherein two said castor assemblies are fitted to the trolley on diagonally opposite comers, with the remaining comers being fitted with conventional castors.

5. A versatile direction priority castor wheel assembly as claimed in claims 1, 2, 3 and 4 where most existing trolleys can be adapted to incorporate the new versatile direction priority castor wheel assembly thus fewer new trolleys need be purchased to use the versatile direction priority castor wheel assembly.

6. A versatile direction priority castor wheel assembly as substantially described in claims I to 5 and with reference to the accompanying drawings I and 2.

4 Amendments to the claims have been filed as follows I. A versatile castor wheel assembly for a hand-propelled vehicle hereafter called a trolley comprising a castor wheel vertically rotatable relative to the vehicle body about a central bolt, a first profiled bearing fixed to the vehicle body and a second complementary profiled bearing fixed to and rotatable with the castor about its vertical axis, the first and second bearings being interposed between the castor and the vehicle body and biassed into permanent contact with one another, characterised in that the bearing profiles possess a vertical plane of symmetry orthogonally to the straight line for-ward motion of the trolley and are uniformly profiled parallel to said plane.

2. A castor assembly according to claim 1 wherein the dimensions of the profiled bearings may be varied in order to tailor the performance and ease of use of the vehicle.

3. A trolley equipped with at least one castor assembly per axle as claimed in any preceding claim.

4. A trolley according to claim 3, wherein the central bolt of said castor assembly is a standard sized bolt, suitable for retrofitting the said castor assembly to existing trolleys without modification of said existing trolleys.