GB2297247A

GB2297247A - Castor with lockable swivelling

Info

Publication number: GB2297247A
Application number: GB9501377A
Authority: GB
Inventors: Piers Mason; Derek Woods
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-01-24
Filing date: 1995-01-24
Publication date: 1996-07-31
Also published as: GB9501377D0

Description

CASTOR This invention relates to castors and more particularly to castors for use on trolleys such as those used to carry goods and propelled manually.

Four wheel trolleys having castor action wheels are widely used to carry goods and luggage in supermarkets, airports and railway stations. In use such trollies may deviate from a straighte path when one or more of the castors meets a discontinuity in the surface over which it is travelling.

After use the trolleys are frequently left in car parks, streets, etc. where they are collected and returned to a storace and collection area. It is essential for compact storage that trolleys can be 'nested', i.e. one trolley fits into another. When scattered trolleys are being collected it is customary to nest each trolley into the previously collected one so that a long assembly of trolleys whith a plurality of wheels is produced. The manouverability of such assemblies of trolleys is poor as each of the many wheels may become randomly aligned.

The present invention provides an improved castor for use on trolleys that has a built in indexing device enabling the castors of trolleys to be aligned easily. This reduces the route deviations caused when pushing loaded trollies across uneven ground. It also assists in manoeuvering nested trollies.

According to the present invention there is provided a castor comprising a frame carrying a wheel mounted on bearings for rotation in a vertical plane and carrying attachment means through a bearing for rotation in a horizontal plane, characterised in that the upper surface of the frame includes an extended peripheral rim in the horizontal plane having an indexing indent at a point where the rim extends over the wheel and in that the attachment means includes a spring loaded rider which rides on the rim with low friction unless engaging the indent.

The horizontal axis of the bearing carrying the wheel is offset from the vertical axis of the bearing providing rotation in a horizontal plane to ensure castor action.

The extended peripheral rim must be rigid and is preferably formed from a metal such as steel although other materials may be used where weight or corrosion resistance is an important factor. The rim is attached to the top of the frame by welding, riveting or other fastening method. The rim may be fitted to the castor at the time of manufacture or attached subsequently. Where the rim passes over the wheel it carries an indexing indent which may be formed by reducing the thickness of the rim or cutting one of more apertures through the rim.

The attachment means fitted to the top of the frame may be a centrally located vertical threaded stud, a screw socket or similar fixing device enabling tie castor to be attached to the base of a trolley. Alternatively the attachment means may comprise a plurality of studs arranged to engage a matching set of apertures on the base of a trolley. The bearing joining the attachment means to the frame is preferably a ball race to ensure low friction and easy castor action. in light duty embodiments the bearing may formed from components having surfaces with a low mutual coeficient of friction such as PTFE and other synthetic polymers.

The spring loaded rider may comprise a radial strip or bar fixed to the attachment means and extending across the peripheral rim. Alternatively the radial strip or bar may be directly attached to the upper surface of the bearing by welding or other fixing method. In some embodiments the radial strip or bar may be rigid while in alternative embodiments a radial strip may be used as a leaf spring arranged to urge the outer end downwardly towards the surface of the rim. Where the radial strip or bar crosses the rim it carries and indexing device in the form of a low friction roller which rides on the upper surface of the rim. The roller may be a wheel carried by a ball race, a single ball or other durable low friction device. The roller is urged downwardly on to the rim by spring means.

The spring may be a resilient strip, as described above, or a compression spring mounted on the radial spring or bar so as to urge the roller towards the surface of the rim.

When the roller reaches the indexing indent in the rim the force required to rotate the frame and wheel in a horizontal plane will be increased so that the wheel is aligned in a manner that directs the attached trolley in a forward direction. A strong twisting movement will release the roller from the indent and allow the trolley to be manoeuvered. It will be seen that while there is a preference for forward movement, created by the combination of the indexing indent and the roller, the overall manoeuverability of a single trolley is substantially unchanged.

However the arrangement enables a user to maintain a pushed trolley on a straight course even on rough terrain.

Furthermore, when a series of trolleys is nested the castors will be preferentially aligned and minor disturances in the terrain over which they are pushed will not misalign any of the castors. The use of a modified castor according to the invention will therefore reduce the energy and skill required to use a trolley and when collecting discarded trolleys and pushing them to a storage area in nested form.

In order that the invention may be more clearly understood, one embodiment thereof will now be described with reference to the single figure which is a schematic side view of a trolley castor with an indexing mechanism according to the invention.

A trolley castor consists of a frame 1 carrying a wheel 2 mounted on bearings for rotation on an axle having threaded ends 3. The ends 3 of the axle are fixed to the frame 1 by means of a nut 4. The upper portion of the frame 1 carries attachment means 5 mounted through bearings, not shown, in a housing 6. The bearings 6 permit the frame 1 and associated wheel 2 to move in a horizontal plane. The attachment means 5 is shown as a threaded stud.

The housing 6 includes an extended peripheral rim 7 in the horizontal plane. The rim 7 has an indexing indent, not s hown, at the point where the rim 7 extends over the wheel 2. A rider 8 mounted for rotation in a holder 9 rides on the rim 7. The holder 9 and associated rider 8 is urged against the rim 7 by a leaf spring 11 to which it is attached. The other end of the spring 11 is fixed to the housing 6 by means of a nut 12.

In use the castor, together with two or more further castors, is attached by means of the stud 5 to the base of a trolley or other carrier which is to be propelled by a pushing action. When the castors are all alingned the riders 8 will be resting in the indexing indent in the rim 7. Gentle pushing without a load will cause the riders to remain in their respective indents and the trolley will tend to move on the castors in a single direction without the need for any steering force. When sufficient steering force is generated for the riders to leave the indents the trolley can be manoeuvered in conventional manner. For collection a train of nested trolleys can easily be aligned after which the tendency of the plurality of castors to move in random directions will be reduced and the train can be directed easily.

Claims

1. A castor comprising a frame carrying a wheel mounted on bearings for rotation in a vertical plane and carrying attachment means through a bearing for rotation in a horizontal plane. characterised in that the upper surface of the frame includes an extended peripheral rim in the horizontal plane having an indexing indent at a point where the rim extends over the wheel and in that the attachment means includes a spring loaded rider which rides on the rim with low friction unless engaging the indent.

2 A castor as claimed in claim 1 characterised in that the horizontal axis of the bearing carrying the wheel is offset from the vertical axis of the bearing providing rotation in a horizontal plane to ensure castor action.

3. A castor as claimed in claim 1 or claim 2. characterised in that the extended peripheral rim is rigid and is formed from a metal.

4. A castor as claimed in any of the preceding claims.

characterised in that the rim is attached to the top of the frame by welding or riveting

5. A castor as claimed in any of the preceding claims.

characterised in that the rim is fitted to the castor at the time of manufacture.

6. A castor as claimed in any of the preceding claims.

characterised in that the rim carries an indexing indent where it passes over the wheel which has been formed by reducing the thickness of the rim.

7. A castor as claimed in any of the claims 1 to 5.

characterised in that the rim carries an indexing indent where it passes over the wheel which has been formed by cutting one of more apertures through the rim.

8. A castor as claimed in any of the preceding claims.

characterised in that the attachment means fitted to the top of the frame is a centrally located vertical threaded stud or a screw socket enabling the castor to be attached to the base of a trolley.

9. A castor as claimed in any of the claims 1 to 7.

characterised in that the attachment means comprises a plurality of studs arranged to engage a matching set of apertures on the base of a trolley.

10. A castor as claimed in any of the preceding claims.

characterised in that the spring loaded rider comprises a radial strip or bar fixed to the attachment means and extending across the peripheral rim.

11. A castor as claimed in any of the claims 1 to 9.

characterised in that the radial strip or bar is directly attached to the upper surface of the bearing by welding or other fixing method.

12. A castor as claimed in any of the preceding claims.

characterised in that the radial bar is rigid and a compression spring is mounted on the radial bar so as to urge its outer end downwardly towards the surface of the rim.

13. A castor as claimed in any of the claims 1 to 11.

characterised in that the radial strip acts as a leaf spring and urges its outer end downwardly towards the surface of the rim.

14. A castor as claimed in any of the preceding claims.

characterised in that where the radial strip or bar crosses the rim it carries an indexing device in the form of a low friction roller which rides on the upper surface of the rim.

15. A castor as claimed in claim 14. characterised in that the roller is a wheel carried by a ball race. a single ball or other durable low friction device

16. Castors as claimed in claim 1 and as herein described.

17. Castors as herein described and illustrated in the accompanying drawing.

18. A trolley having a set of four castors as claimed in any of the claims 1 to 17.