WO1994015802A1

WO1994015802A1 - Castor support

Info

Publication number: WO1994015802A1
Application number: PCT/AU1993/000686
Authority: WO
Inventors: Robert Joseph Reader
Original assignee: Robert Joseph Reader
Priority date: 1992-12-30
Filing date: 1993-12-24
Publication date: 1994-07-21

Abstract

A castor support for a castor (11) supported from a web (12) of a trolley where the castor comprises a ground support element such as a wheel (14) rotatably supported from a housing (15) supported from an upstanding shaft (17) to be rotatable about the shaft about one axis which is offset from the ground support element (14) where a stop surface (18) is provided on the shaft adjacent or on the housing, to be in face to face engagement with one face of the web (12) and the shaft is associated with a nut (19) and/or washer receivable over the shaft wherein the castor support comprises cushioning members (20 and 21) which are each receivable over the shaft (17), one cushioning member (20) located to one side of the web (12) and clampingly engaged between the web (12) and the stop surface (18) and the other cushioning member (21) being clampingly engaged between the web (12) and washer and/or nut (19) respectively, a rigid support element (22) having two ends, one end of the support element is adapted to be fixed to the web (12) adjacent the castor (11) and the other end of the support element (22) is adapted to be supported from the frame (13) of the trolley; the support element being shaped to accommodate and transfer some loading applied to the web by the castor, to the frame (13) of the trolley.

Description

CASTOR SUPPORT

THIS INVENTION relates to trolleys and in particular relates to the castor mountings for trolleys.

A difficulty which has been encountered in relation to trolleys in the past and particularly four wheeled trolleys where at least two of the wheels are castor wheels and this difficulty relates to the damage to the castor wheels which tends to result in mis-alignment of those wheels and which adversely affects their castoring action. This is particularly apparent in relation to trolleys which are used in shopping centres which are renowned for having "a mind of their own" . Such mis-alignment of the castors can be as a result of a number of things including; the deformation of the support for the castor which causes the central shaft of the castor to be offset from the vertical axis; and/or the bending of the castor shaft out of the vertical axis; and/or deflection of the housing supporting the castor wheel from the shaft.

Attempts to prevent the mis-alignment of the castors have traditionally involved strengthening the support which supports the castor wheels on the trolley to prevent deformation of that support. The effect of such however is that when the castor is subjected to a sudden jolt, there is no accommodation within the mounting for the castor to accommodate for that jolt. If the web is unable to deflect due to the degree of reinforcement, deflection will occur in the shaft of the castor and/or the housing of the castor which can result in the bending of the shaft or housing and/or shearing of the shaft.

In order to effect the deformation of a metal web, a force must be applied to the web which is greater that the stress breaking limit. If no load is applied to the web the natural resilience of the web will absorb much of the force applied. If however the web is already loaded to a small extent only the amount of additional force required to effect deformation is reduced significantly.

In the case of a shopping trolley which is carrying a load, the shocks which are applied to the web which constitutes the castor support as a result of the shopping trolley being moved over a rough surface can comprise in a single shock or a series of closely spaced repetitive shocks being applied by the castor through its shaft and/or housing to the web which can result in plastic deformation of the castor shaft or web.

It is an= object of this invention to provide a support for a trolley castor which will permit some accommodation by the castor and/or the support therefor on excessive loads being exerted without resulting in permanent deformation of the support or shaft.

Throughout this specification, the term "castor" shall be taken to referring to a ground support in the form of a wheel or a like ground support element rotatably supported from a housing which is supported from an upstanding shaft to be rotatable about the axis of the shaft which is offset from the ground support element and where the shaft is receivable through an aperture in a support web and where a stop surface is provided on the shaft adjacent, or on the housing, to be in face to face engagement with one face of the web and the shaft is associated with a nut and/or washer receivable over the shaft to be clampingly engaged with the other face of the web and where the web is provided on a trolley.

In one form the invention resides in a castor support for a trolley comprising cushioning members which are each receivable over the shaft, to be located to each side of the web and clampingly engaged between the web and the stop surface -and between the web and the washer and/or nut respectively; a rigid support element having two ends wherein the support element is adapted at one end to be fixed to the web adjacent the castor, the other end of the support element being supported from the body of the trolley; the support element being shaped to accommodate and transfer some loading applied to the web by the castor to the frame of the trolley.

According to a preferred feature the one end is fixed directly to the web.

According to a further preferred feature the other end is fixed to the frame of the trolley.

The invention will be more fully understood in the light of the following description of two specific embodiments. The description is made with reference to the accompanying drawings" of which;

Figure 1 is an isometric view of a castor support according to the first embodiment;

Figure 2 is a schematic sectional view of a castor support according to the first embodiment;

Figure 3 is a plan view of the castor support of the first embodiment;

^' Figure 4 is a plan view of the castor support according to the second embodiment; and

Figure 5 is an end elevation along line 5-5 of Figure 4.

The first embodiment relates to a castor support which is to be used in association with a shopping centre trolley. Such shopping centre trolleys generally comprise at least one pair of castors 11 which are supported from a transverse web 12 in the form of a flat bar which extends across the lower portion of the forward end of the frame 13 of the trolley. The castors each comprise a wheel 14 which is rotatably supported from a fork-like housing 15 by an axle 16. The housing 15 supports an upstanding shaft 17 which is substantially perpendicular to the ground and is offset to one side from the axle 16. The uppermost surface 18 of the housing 15 adjacent the shaft 17 is substantially planar and perpendicular to the axis of the shaft 17 and serves to provide a stop surface which normally would bear against the underneath of the web 12. The shaft 17 is normally associated with a nut 19 and associated washer. The nut is threadably engageable with the shaft 17 and is intended to force the washer against the upper surface of the web 12.

The chassis of the trolley comprises a frame having a generally U-shaped configuration which extends forwardly from a pair of rear uprights where the end of each arm is fixed to the respective upright. The frame 13 is formed by a pair of parallel horizontal frame members which are spaced one above the other and are interconnected by cross member 27 at spaced intervals. The frame members are of a generally circular cross-section.

The first embodiment comprises an elongate support element 22. The support element 22 is formed of an elongate torsional members 23 formed of a flat section. One end of the torsional members 23 is provided with a laterally extending flange 24 having an aperture therein which is dimensioned to be received over the shaft 17 of the castor 11. The other end of the flat section is formed with a transverse plate member 28 which is dimensioned to be received between the pair of frame members 26 of the trolley frame 13 and the ends 29 are shaped to be complementary to the frame member 26 such that it is rigidly retained in position between the frame members.

The embodiment further comprises a pair of laminar members 20 and 21 (see Figure 2) which are resiliently compressible axially and which may be formed from a material such as rubber, polyurethane or a like elastomeric material. Alternatively the laminar members may comprise resilient metal washers. One laminar member 20 is located over the shaft 17 and lies on the support surface 18 of the housing 16 to be clamped between the support surface and the under surface of the web 12 while the other laminar member 21 is adapted to be received over the shaft 17 and lie adjacent the upper face of the flange 24 beneath the nut 19 and washer.

It has been found that the presence of the castor support according to the embodiment does not necessitate the further strengthening of the web 12 of the trolley frame, since the support arrangement is able to accommodate for the loadings which are likely to be exerted upon the castor during its normal use. The presence of the laminar members 20 and 21, which are not fully compressed by the clamping action of the nut 19 serves to resiliently accommodate for at least some of the shock loadings which are applied onto the castor and which act to cause deflection of the shaft from the vertical axis. Furthermore, the presence of the support element 22 serves to apply some pre-loading to the web member 12 to initially resist the torsional deflection of the web member which would normally occur when a load is exerted upon the trolley. In addition the support serves to transfer some of the loading to the chassis of the trolley. As a result, if a sudden shock load is exerted upon the castor of the loaded trolley, the web member is still able to undergo elastic deformation. As stated previously it has been found that the damage to the castoring arrangement of the castors of a shopping trolley seems to occur as a result of shock loads being applied to the castor during the operation of a loaded trolley. In this regard, it has been found that where the web is placed under load, any sudden shocks or loads which are applied to the metal section while still under load, will result in plastic deformation of the metal. It is believed that this effect contributes to a significant amount of damage occurring to the castors of the trolleys. In the situation where the trolley is under load and the castor is subjected to a sudden load as a result of encountering an obstruction or being caused to vibrate as a result of the passage of the trolley over a tiled surface, brick paving or expansion joints or the like surface the additional loading which is so induced serves to bring the total load on the web 12 to the stress breaking limit of the castor and/or its mounting. The resultant sudden application of the additional load to the loaded web supporting the castors results in plastic deformation of the web and/or shaft of the castor.

In the case of the first embodiment, the presence of the cushioning laminar members 20 and 21 serves to provide for some accommodation of the loadings that may be applied to the castor during operation and to allow for some elastic movement of the shaft with respect to the web to accommodate for that load. Furthermore the presence of the support element 23 serves to support and pre-load the web in the region of the castor and flex when the trolley is under load to prevent deflection of the web member to or beyond its elastic limit. In so flexing the bracket serves to transfer some of the stress exerted on the web to the chassis of the trolley. Therefore if a sudden shock loading is applied to the web through the castor, the shock loading can be accommodated for by the elastic deformation of the web without causing any plastic deformation. Furthermore, the first embodiment provides a very convenient means of modifying existing trolleys to be more resistant to damage.

In the case of the second embodiment shown at Figures 4 and 5 the one support element 122 is applied to both castors. The support 122 comprises a plate 124 which is applied over the web 112 and over the shafts 118 of both of the castors to be clamped by means of nuts 119. As in the case of the first embodiment laminar cushioning members (not shown) are located over the shaft 118 of each castor at the underside of the web 112 and the upper face of the plate 124.

Further support is provided by a pair of torsion member 123 which each comprise a length of tube fixed at one end to the plate 124. The other ends 125 of the torsion member are swagged to a profile whereby they are snugly received over the tubular frame member 113 of the trolley chassis. The spacing between the other ends of the torsion members 123 is such that they are very snugly received against the opposed faces of the frame members 113 when the plate is in position over the web.

The second embodiment has been found to achieve all of the advantages provided by the first embodiment.

If desired the cushioning members 20 and 21 may take the form of a grommet-like member received over the shaft 17 of the castor and received in an enlarged aperture provided in the web and in the flange 24 or plate 124. The grommet may have a flange at either end which will be clampingly engaged between the web 12 and the support surface 18 and between the flange 24 or plate 124 and the washer and nut 19. In addition, a single grommet-like member may provide both cushioning members 20 and 21. In additional if desired the cushioning members may comprise a resilient dome or cone shaped washer which can be resiliently compressed. An example of such a washer comprises a "Belvil" washer. Furthermore the cushioning members may comprise a stack of two or more such washers.

If desired the support element may be rigidly mounted to the web and trolley frame. In addition the mounting of the support to the web need not be effected by being applied over the shaft of the castor but may be by any means such as welding directly to the web.

It should be appreciated that the scope of the present invention need not be limited to the particular scope of the embodiment described above.

Claims

THE CLAIMS defining the invention are as follows :-

1. A castor support for a trolley comprising cushioning members which are each receivable over the shaft, one cushioning member to be located to one side of the web and clampingly engaged between the web and the stop surface and the other cushioning member being clampingly engaged between the web and washer and/or nut respectively, a rigid support element having two ends, one end of the support element is adapted to be fixed to the web adjacent the castor, the other end of the support element is adapted to be supported from the frame of the trolley; the support element being shaped to accommodate and transfer some loading applied to the web by the castor, to the frame of the trolley.

2. A castor support as claimed at claim 1 wherein the support element is fixed at its one end directly to the web.

3. A castor support as claimed at claim 1 or 2 wherein the support element is fixed at its other end to the frame of the trolley.

4. A castor support as claimed at claim 1 wherein the support element is formed at its one end with a plate element having an aperture receivable over the shaft where the plate element is clampingly received between the web and the one cushioning member.

5. A castor support as claimed at claim 4 wherein the other end of the support element is rigidly engaged by the frame of the trolley.

6. A castor support as claimed at claims 4 or 5 wherein the support element is formed of a flat section the plane of which is substantially parallel to the shaft axis.

7. A castor support as claimed at claim 4 or 5 wherein the support element has a generally circular cross-section.

8. A castor support as claimed at claim 4, 5, 6 or 7 wherein a single plate element extends over the web to be received over the shaft of all castors supported by the web a support element extending from each end of the plate member to be engageable with opposite sides of the frame of the trolley.

9. A castor support as claimed at any one of the preceding claims wherein the cushioning members comprises a laminar member formed of a resiliently compressible material.

10. A castor support as claimed at claim 9 wherein the resiliently compressible material is selected from rubber, polyurethane, an elastomer or like material.

11. A castor support as claimed at claim 9 or 10 wherein the cushioning member is formed as a grommet-like member receivable in the aperture provided in the web and plate member.

12. A caster support as claimed at claim 11 wherein the one and other cushioning members are provided by a single grommet-like member.

13. A castor support as claimed at any one of the preceding claims wherein the cushioning member comprises one or more resilient washers formed of metal.

14. A castor support as claimed at any one of the preceding claims where in the cushioning members are only partially compressed when clampingly engaged. - il ¬ ls. A castor support substantially as herein described.