GB2428188A

GB2428188A - Castor with removable axle and wheel

Info

Publication number: GB2428188A
Application number: GB0613718A
Authority: GB
Inventors: Robert Potts; Brian Townsend
Original assignee: Spire Group Ltd
Current assignee: Spire Group Ltd
Priority date: 2005-07-11
Filing date: 2006-07-11
Publication date: 2007-01-24
Also published as: GB0514176D0; GB0613718D0

Abstract

A castor 10 comprising a mounting bracket 12, an axle 14 and a castor wheel 16, the castor wheel 16 being rotatably mounted upon the axle 14 and the axle 14 being removably mounted upon the mounting bracket 12. The axle 14 may be mounted on a housing 26 which is removable from the mounting bracket 12. This allows the housing 26, axle 14 and castor wheel 16 to be removed and separated from one another. The housing 26 may be retained in the mounting bracket 12 by a retaining member, preferably a resilient lip (see Figure 3). The housing 26 may have two aligned holes 34 for receiving the axle 14 and the mounting bracket 12 has two surfaces which overlie the holes 34.

Description

CASTOR

FIELD OF THE INVENTION

$ This invention relates to a castor.

BACKGROUND TO THE INVENTION

Castors are in widespread use upon furniture items and the like. A castor comprises a castor wheel mounted to rotate about an axle, the axle being carried upon a support bracket. Two general types of castor are known.

In the first type the support bracket is mounted to swivel about an axis substantially perpendicular to the axle, so that the furniture item (or other article to which the castor is fitted) may be pushed or pulled in any direction and the bracket will swivel to orient the castor wheel with the direction of movement; such a castor will typically be fitted to a bed for example.

In the second type the support bracket is mounted directly to the article, and the axle of the castor wheel is fixed relative to the article and cannot swivel re'ative thereto. The present invention is directed to the second type of castor.

The second type of castor is used, for example, on chairs, the castors being fitted to the two rear legs only, and normally lying out of engagement with the floor.

When it is to be moved the chair (which should not be occupied) can be tipped backwards which brings the castor wheels into engagement with the floor and allows the chair to be rolled across the floor. Since there are only two wheels in engagement with the floor the chair can be steered as it is being moved, and this is why the castor bracket does not need to be swivelabte.

Chairs such as those described above are used, for example, in rest homes and other institutions. The chairs are necessarily robust as they may be in use for long periods of time, by many different persons, and the provision of the castors makes them easier to move if desired. For simplicity the following description relates to such use, but the invention is not limited to these applications.

DESCRIPTION OF THE PRIOR ART

The castors of the second type which are presently used on chairs are of basic design7 having a bracket adapted to locate adjacent the bottom of a rear leg of the chair, the bracket carrying the axle upon which the castor wheel is rotatably mounted.

Traditionally, castors of the first type and the second type have been permanently constructed, which seldom causes undue problems because of the relatively small distance a castor would be required to roll during the lifetime of the article to which it is fitted. However, chairs used in institutions such as rest homes are moved relatively often, and usually over carpeted surfaces, and it has become a concern that fibres from the carpeting, and other materials, will foul the axle and lead to a degeneration in operation of the castor, so increasing the effort required to roll the chair across the floor.

SUMMARY OF THE INVENTION

It is therefore the object of the present invention to provide a castor which reduces of avoids the problems associated with the known castors described above.

Accordingly, there is provided a castor comprising a mounting bracket, an axle and a castor wheel, the castor wheel being rotatably mounted upon the axle and the axle being mounted upon the mounting bracket, charactensed in that the axle is removably mounted upon the mounting bracket.

The invention therefore provides a demountable castor wheel in that the axle and castor wheel can be removed from the mounting bracket for cleaning and/or servicing.

Preferably, the castor wheel is removably mounted upon the axle, so that the axle and castor wheel can be separated when removed from the mounting bracket.

Desirably, the axle and castor wheel are mounted in a housing which is carried by the mounting bracket, the housing (with the axle and castor wheel) being removable from the mounting bracket.

Preferably, the housing is a sliding fit into the mounting bracket, and is retained therein by a retaining member. Preferably also the retaining member is a resilient lip carried by the mounting bracket.

Usefully, the retaining member is only required to retain the housing relative to the mounting bracket when the castor is not is use, i.e. when the chair has all four feet on the floor and the castor wheel does not engage the floor; when the castor wheel engages the floor it can be arranged that the weight of the chair acts to retain the housing relative to the mounting bracket.

Preferably, the housing has a pair of aligned holes to receive the ends of the axle, and the mounting bracket has surfaces which overlie the holes when the housing is mounted thereto. In this way, the axle may be slid out of the housing when this is released from the mounting brakcet, but is retained in position within the housing by the surfaces when the housing is mounted to the mounting bracket.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. I is a side view of a castor according to the invention; Fig.2 isa plan view of the castor of Fig.I; Fig.3 is a side view of the mounting bracket of the castor of Fig. I; Fig. 4 is a detailed view of the retaining member of the mounting bracket; Fig. 5 is a front view of the mounting bracket; Fig.6 is a side view of the housing of the castor of Fig. I; Fig.7 is a front view of the housing; Fig.8 is a plan view of the housing; Fig.9 is a side view of the axle; and Fig. 10 is a side view of the castor wheel.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The castor 10 comprises a mounting bracket 12, an axle 14, and a castor wheel 16. The castor wheel 16 is rotatably mounted upon the axle 14, and both are mounted upon the mounting bracket 12. The mounting bracket 12 in this embodiment is adapted to be mounted upon the leg of a chair (not shown), the leg being of curved periphery so that the mounting surface 20 (Fig.2) is correspondingly curved. The mounting bracket 12 has two holes 22 (see also Fig.5), each of which can receive a screw 24 or the like by which the mounting bracket 12 can be secured to the leg of the chair.

Clearly, in other embodiments the castor can be adapted for fitment to another article, or the chair leg can be other than curved, and the mounting surface 22 will be shaped accordingly. Alternatively, the mounting surface 22 can be made flat, and a separate component can be produced to lie between the mounting surface and the article to which the castor is to be fitted, the separate component having suitably shaped mounting surfaces.

It will be noted that in its normal orientation of use as shown in Fig.1 the castor wheel 16 is not the lowest part of the castor, and will not therefore normally engage the floor upon which the chair rests. However, in use the castor projects rearwardly from the chair leg so that when the chair is tipped backwards the castor wheel 16 can be brought into engagement with the floor and allow the chair to be rolled thereacross in known fashion.

The axle 14 and most of the castor wheel 16 are shown in dotted outline in Figs. I and 2 since these parts are not visible, i.e. the mounting bracket 12 has two side panels 26 which overlie the ends of the axle 14 and obscure most of the castor wheel 16. Part of the castor wheel 16 does, however, project beyond the side panels 26, which is necessary so that the castor wheel can be brought into engagement with the floor.

Figs. 6-8 show the housing 30 which can be located within the mounting bracket, and Figs. 3-5 show the mounting bracket absent the housing 30. The mounting bracket 30 includes two spaced side walls 32, which are separated by a distance slightly greater than the thickness of the castor wheel 16, and therefore allow the castor wheel 16 to be located therebetween. The castor wheel 16 is retained in the housing 30 by the axle 14 which is slidingly mounted in the aligned through- holes 34 in the side walls 32 of the housing 30. As shown in Fig.10 the castor wheel has a central through-hole 36 wtuch can receive the axle 14.

The axle 14 is preferably of metal, and the castor wheel 16 and the housing 30 are preferably plastics mouldings. No bearings are included in this embodiment since they are not believed necessary in the vast majority of applications of the castor. Thus, the castor 16 can rotate substantially freely about the axle 14, and the ends of the axle 14 can rotate relatively freely within the holes 34 (importantly, it does not matter where the relative rotation takes place, and references herein to the castor wheel mounted to rotate upon the axle could equally well embrace a situation in which all of the rotation occurs between the ends of the axle and the holes 34 so that the axle 14 rotates with the castor wheel 16).

The housing 30 is adapted to be a sliding fit into the mounting bracket 12, and in particular to be a sliding fit between the side walls 26 thereof. Thus, the housing 30 is slid into the mounting bracket 12 in the direction of the arrow A of Figs.3 and 5, until its top surface 38 engages the top wall 40 of the mounting bracket 12.

As shown in Figs 6-8, the top surface 38 of the housing carries an extension piece 42, and as shown in Fig.3 the top wall 40 of the mounting bracket 12 has a correspondingly shaped opening 44 into which the extension piece 42 can locate.

The purpose of the opening 44 is to allow access to the top of the housing 30 in order to press the housing downwardly to release it from the mounting bracket 12.

Thus, it Will be observed from Figs. 7 and 8 that the side walls 32 of the housing are tapered slightly, and the internal surfaces of the side walls 26 of the mounting bracket 12 are correspondingly tapered. This tapering ensures more accurate and secure location of the housing 30 in the mounting bracket 12. It will be understood that when the weight of the chair is being borne by the castor wheel 16 the housing 30 is forced upwardly relative to the mounting bracket 12.

When it is desired to separate the housing 30 from the mounting bracket 12 the taper may cause these parts to be held firmly together so that force is required to be imparted to the extension piece 42 to release the housing 30 from the mounting bracket 12.

It is however not desirable to rely solely upon the tapered side walls 32, 26 to retain the housing 30 in its correct position relative to the mounting bracket 12, and for this purpose the mounting bracket carries a lip 46 (Figs. 3 and 4) which engages the underside of the fitted housing 30 and retains this in position. The lip 46 in this embodiment is an integral part of the mounting bracket 12, and since the mounting bracket is preferably made from a plastics material it can be arranged that the lip is sufficiently resilient to allow the housing to be forced out of the mounting bracket 12 when required.

As shown in Fig.8, in this embodiment the housing 30 includes two channels 50 which locate about corresponding rails on the inside of the side walls 26 of the mounting bracket 12. The purpose of the cooperating channels 50 and rails is to increase the rigidity of the assembled castor, and in particular to oppose any tendency of the housing 30 to move laterally relative to the mounting bracket 12 when the castor wheel 16 is supporting the weight of the chair.

It will be observed from Fig.1 that the side walls 26 of the mounting bracket 12 overlie the holes 34 when the housing 30 is located therein, so that the axle 14 is retained relative to the housing 30 with its ends supported by the holes 34. When the housing 30 is removed from the mounting bracket 12, however, the axle 14 may be slid out of the holes 34, and out of the castor wheel 14, allowing the components to be separated and cleaned as required. In addition, if any part of the castor is damaged it can be replaced without requiring replacement of the complete castor.

Claims

1. A castor comprising a mounting bracket, an axle and a castor wheel, the castor wheel being rotatably mounted upon the axle and the axle being removably mounted upon the mounting bracket.

2. The castor according to Claim I in which the castor wheel is removably mounted upon the axle, so that the axle and castor wheel can be separated when removed from the mounting bracket.

3. The castor according to Claim 1 or Claim 2 in which the axle and castor wheel are mounted in a housing which is camed by the mounting bracket, the housing being removable from the mounting bracket.

4. The castor according to Claim 3 in which the housing is a sliding fit into the mounting bracket.

5. The castor according to Claim 3 or Claim 4 in which the housing is retained in the mounting bracket by a retaining member.

6. The castor according to Claim 5 in which the retaining member is a resilient lip carried by the mounting bracket.

7. The castor according to any one of Claims 3-6 in which the housing has a pair of aligned holes to receive the ends of the axle, and the mounting bracket has surfaces which overlie the holes when the housing is mounted thereto.

8. A castor constructed and arranged substantially as described in relation to Figs. 1-10 of the accompanying drawings.