GB2092079A - Wheel for castors - Google Patents

Abstract

A castor wheel comprises a large diameter hub 2 having an outwardly facing bearing track 12 for ball bearings 3 received in a track 13 on an outer wheel member 4 which carries a tyre 5 and is rotatable about the hub. The hub diameter may be about half the overall diameter of the wheel, and the hub may be of one- piece construction or, as shown, formed of two interfitting members 6, 7. <IMAGE>

Description

SPECIFICATION Improvements in wheels This invention relates to a wheel primarily for a swivelling castor.

A wheel in accordance with the present invention comprises a hub of substantial radius with a peripheral bearing track of substantial length, an outer annular wheel member with a complementary bearing track and interposed bearings. In a conventional wheel the hub has a small radius and a correspondingly short bearing track.

Thus in a typical embodiment the hub may have a diameter just under half that of the wheel as a whole.

A particular embodiment of the invention will now be descirbed by way of example and with reference to the accompanying drawings wherein: Figure 1 is a side elevation of a wheel in accordance with the present invention; and Figure 2 is a section on the line x-x of figure 1.

A wheel, hub, and bearing assembly 1 for a swivelling castor comprises; a hub 2, ball bearings 3, an outer wheel member 4 and a tyre 5.

The hub 2 comprises two substantially mirror image segments 6 and 7 joined together at a plane perpendicular to the rolling axis 8 of the wheel 4. Segment 6 is joined to segment 7 by a plurality of pegs 9 which extend outwardly from segment 6 parallel to the rolling axis 8, and frictionally engage in corresponding bores 10 in segment 7. An embodiment is envisaged wherein the hub is of unitary construction.

The outer edge parts 11 of segments 6 and 8 define circumferential outwardly facing bearing track 12 having a semicircular concave cross section, which faces outwardly from the rolling axis 8. The track for bearings 12 lies in and is symmetrically deposed about the plane dividing the two segments 6 and 7.

The wheel 4 has an annular track for bearings 13, corresponding to bearing track 12, having a semicircular concave cross-section which faces inwardly to the rolling axis 8 and bearing track 12.

Ball bearings 3 are located in the annular space, having a substantially circular cross section, defined by bearing tracks 12 and 13 between hub 2 and wheel 4.

An annular web 14 extends radially outwardly from the bearing track 13 to an annular rim 1 5 which defines an outwardly facing concave tyre wall 16. A circular tyre 5 is frictionally located in the tyre well 16 and defines a rolling surface 18 having a convex cross section which faces radially outwardly from the rolling axis 8.

In use the outer wheel member 4 rotates about the hub 2 if a rotational force perpendicular to the rolling axis 8 is applied to the wheel member 4, the ball bearings rolling freely around in the bearing tracks 12 and 13. If a lateral force parallel to the rolling axis 8 is applied to the wheel member 4, and the hub 2 is in a fixed position, the wheel member 4 will be restrained from lateral movement by the ball bearings 3 located in the bearing tracks 12 and 13.

An advantage of the present invention is that the bearing track has a large radius which allows a low point loading on the relatively large ball bearings used. The low loading leads to minimal bearing track wear. In the embodiment being specifically described the wheel has an overall diameter of 125 mm. The hub has a diameter of 56 mm i.e. 0.45 of the wheel. The length of the bearing track is 176 mm. The bearing balls have a diameter of 7 2 mm.

Reference is made to our copending application No. 8014993, and superseded by E.P.C.

Application No. 81301967.6.

1. A wheel for a swivelling castor, such wheel comprising a hub of substantial radius with a circumferential outwardly facing bearing track of correspondingly substantial length, outer wheel member with a complementary bearing track and interposed bearings.

2. A wheel as claimed in Claim 1 wherein the hub is of the order of half the overall diameter of the wheel.

3. A wheel substantially as herein described with reference to, and as shown in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in wheels This invention relates to a wheel primarily for a swivelling castor. A wheel in accordance with the present invention comprises a hub of substantial radius with a peripheral bearing track of substantial length, an outer annular wheel member with a complementary bearing track and interposed bearings. In a conventional wheel the hub has a small radius and a correspondingly short bearing track. Thus in a typical embodiment the hub may have a diameter just under half that of the wheel as a whole. A particular embodiment of the invention will now be descirbed by way of example and with reference to the accompanying drawings wherein: Figure 1 is a side elevation of a wheel in accordance with the present invention; and Figure 2 is a section on the line x-x of figure 1. A wheel, hub, and bearing assembly 1 for a swivelling castor comprises; a hub 2, ball bearings 3, an outer wheel member 4 and a tyre 5. The hub 2 comprises two substantially mirror image segments 6 and 7 joined together at a plane perpendicular to the rolling axis 8 of the wheel 4. Segment 6 is joined to segment 7 by a plurality of pegs 9 which extend outwardly from segment 6 parallel to the rolling axis 8, and frictionally engage in corresponding bores 10 in segment 7. An embodiment is envisaged wherein the hub is of unitary construction. The outer edge parts 11 of segments 6 and 8 define circumferential outwardly facing bearing track 12 having a semicircular concave cross section, which faces outwardly from the rolling axis 8. The track for bearings 12 lies in and is symmetrically deposed about the plane dividing the two segments 6 and 7. The wheel 4 has an annular track for bearings 13, corresponding to bearing track 12, having a semicircular concave cross-section which faces inwardly to the rolling axis 8 and bearing track 12. Ball bearings 3 are located in the annular space, having a substantially circular cross section, defined by bearing tracks 12 and 13 between hub 2 and wheel 4. An annular web 14 extends radially outwardly from the bearing track 13 to an annular rim 1 5 which defines an outwardly facing concave tyre wall 16. A circular tyre 5 is frictionally located in the tyre well 16 and defines a rolling surface 18 having a convex cross section which faces radially outwardly from the rolling axis 8. In use the outer wheel member 4 rotates about the hub 2 if a rotational force perpendicular to the rolling axis 8 is applied to the wheel member 4, the ball bearings rolling freely around in the bearing tracks 12 and 13. If a lateral force parallel to the rolling axis 8 is applied to the wheel member 4, and the hub 2 is in a fixed position, the wheel member 4 will be restrained from lateral movement by the ball bearings 3 located in the bearing tracks 12 and 13. An advantage of the present invention is that the bearing track has a large radius which allows a low point loading on the relatively large ball bearings used. The low loading leads to minimal bearing track wear. In the embodiment being specifically described the wheel has an overall diameter of 125 mm. The hub has a diameter of 56 mm i.e. 0.45 of the wheel. The length of the bearing track is 176 mm. The bearing balls have a diameter of 7 2 mm. Reference is made to our copending application No. 8014993, and superseded by E.P.C. Application No. 81301967.6. CLAIMS

1. A wheel for a swivelling castor, such wheel comprising a hub of substantial radius with a circumferential outwardly facing bearing track of correspondingly substantial length, outer wheel member with a complementary bearing track and interposed bearings.

2. A wheel as claimed in Claim 1 wherein the hub is of the order of half the overall diameter of the wheel.

3. A wheel substantially as herein described with reference to, and as shown in the accompanying drawings.