US3818541A

US3818541A - Castors

Info

Publication number: US3818541A
Application number: US00319497A
Authority: US
Inventors: Raymond Robert James Daniels
Original assignee: Guy Raymond Engineering Co Ltd
Current assignee: Guy Raymond Engineering Co Ltd
Priority date: 1972-01-07
Filing date: 1972-12-29
Publication date: 1974-06-25
Anticipated expiration: 1991-06-25
Also published as: AU5071673A; DK135752B; NO135207B; NO135207C; DE2300720A1; AU468638B2; GB1373582A; DK135752C; FR2167763B1; FR2167763A1

Abstract

A castor for attachment to a leg or base of an article of furniture comprising a hollow shell of synthetic plastics material open at the bottom to receive a roller and having two spaced side walls. A shaft is mounted across the side walls of the shell, the shaft having grooved ends which are located in Tsection sockets formed in the inner surfaces of the side walls of the shell so as to be hidden from view and so as to support and retain the side walls of the shell against both compressive and bursting forces. A free running roller is mounted on the shaft and vertical support means are provided on the shell, offset laterally from the shaft for mounting the shell pivotally on a supporting member.

Description

United States Patent [191 Daniels CASTORS [75] Inventor: Raymond Robert James Daniels,

Kings Lynn, England [73] Assignee: Guy Raymond Engineering Company Limited, King's Lynn. Norfollg, Ergland [22] Filed: Dec. 29, 1972 [2]] Appl. No.: 319,497

30 Foreign Application Priority Data Jan. 7, 1972 Great Britain 889/72 [52] US. Cl. 16/18 A, 16/31 R, 16/48 [51] Int. Cl. B60b 33/00, A47b 89/00 [58] Field of Search 16/22, 23, 25, 30, 31, 16/40, 18, 18 A, 20, 27, 29, '37, 38, 43, 45-48, 91, 97, 98, 106, 107, 18 R [56] References Cited UNITED STATES PATENTS 19,369 2/1858 Kinzer 16/18 R 300,782 6/1884 Koch 16/45 409,495 8/1889 Pederson 16/18 R 556,978 3/1896 Hetzel 16/48 2,170,257 8/1939 Andersen l6/3l R 1 June 25, 1974 3,210,795 10/1965 Fontana et al 16/43 3,343,204 9/1967 Ford 3,345,675 10/1967 Haydock 16/45 3,451,095 6/1969 Kiefer 16/107 3,537,125 11/1970 Arenson 16/31 R 3,713,186 l/l973 Cartwright l6/45 FOREIGN PATENTS OR APPLICATIONS 1,007.210 10/1965 Great Britain 16/18 A Primary Examiner-Donald A. Griffin ABSTRACT pressive and bursting forces. A free running roller ismounted on the shaft and vertical support means are provided on the shell, offset laterally from the shaft for mounting the shell pivotally on a supporting member.

4 Claims, 8 Drawing Figures PATENTED JUNZ 51374 SHEET 1 OF 2 PATENTEB JUNZ 51874 SHEET 2 OF 2 1 cAsToRs BACKGROUND TO THE INVENTION The present invention relates to a castor for attachment to the leg or base of an article of furniture.

In the design and manufacture of castors for fumiture, it is necessary to ensure that the castor has sufficient strength to take the weight of the article of fumiture, that it can roll easily in any direction and that it has a bearing surface which minimises damage to the floor surface on which the castor stands and moves. It is also necessary to ensure that the castor can be economically manufactured and has a pleasing appearance.

A conventional castor comprises a roller mounted on a horizontal shaft, the ends of which are journalled in a rigid housing or shell which is itself pivotally mounted on a vertical shaft which is offset from the roller shaft so that the shell and roller can rotate about a vertical axis and the roller can rotate about a horizontal axis. The shell of this type of castor has been formed from a metal or metal alloy rather than a synthetic plastics material although synthetic plastics materials have substantial cost and design advantages, because it has not been possible hitherto to design a housing having sufficient strength and rigidity from a synthetic plastics material.

It is therefore an object of the present invention to provide a castor having a moulded synthetic plastics shell which has sufficient structural strength and rigidity to withstand the stresses to which a castor is subjected in'normal use.

It is a further object of the present invention to provide a castor in which the ends of the roller shaft are hidden from view and which thus has a pleasing external appearance.

STATEMENT OF THE INVENTION The castor of the present invention comprises a hollow shell of synthetic plastics material open at the bottom to receive a roller and having two spaced side -walls, a shaft mounted across the side walls of the shell so as to support the side walls of the shell against compressive and bursting forces, a free running roller mounted on the shaft and vertical support means on the shell offset laterally from the shaft for mounting the shell pivotally on a supporting member.

Preferably the internal face of each side wall is formed with a T-section socket, the shaft is formed with a groove adjacent each end of the shaft and the ends of the shaft are slidably engaged in the slots, so as to be contained wholly within the castor.

The roller can be formed from any suitable material but is preferably moulded from a synthetic plastic such as nylon and may comprise two similar portions which are independently rotatable.

DESCRIPTION OF THE DRAWINGS roller removed;

FIG. is a section taken on the line V-V of FIG. 3;

FIG. 7 is a view of a detail of the roller of FIGS. 1 to 6 on an enlarged scale; and

FIG. 8 is a section similar to FIG. 6'but taken through a modified castor.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawings a castor is indicated generally at 10 which comprises a hollow shell 11, a shaft 12 mounted I in the shell 1 l and a roller 13 which is mounted for free rotation on the shaft 12. 1

The shell is formed as an injection moulding from a synthetic plastics material such as nylon or ABS and is hollow so as to form a cavity to accept the roller 13. The shell 11 is formed with two

side walls

14 and 15 respectively, two

end walls

16 and 17 respectively and an upper wall 18. The side walls and the end walls are outwardly slightly convex in shape to give a pleasing appearance to the shell and the upper wall 18 slopes downwardly towards the front end wall 17.

A boss 19 projects upwardly from the upper wall 18 adjacent the rear end wall 16 and the boss 19 is formed with support means comprising a bore 20 adapted to receive a spigot.

The

side walls

14 and 15 of the shell 11 are formed with upwardly extending thickened

portions

21 and 22 respectively on their inside faces and slots or

sockets

23 and 24 are formed in the thickened

portions

21 and 22 respectively. Each

socket

23 and 24 is T-shaped in cross-section and extends a short distance upwardly from the bottom edge of the respective side walls.

The shaft 12 is formed with

grooves

25 and 26 respectively adjacent its ends and the dimensions of the T-

section sockets

23 and 24 are such that the grooved ends of the shaft 12 are a press fit into the

sockets

23 and 24, as shown in FIG. 4. Two convex shaft retaining cam faces, 27 and 28, are formed on the facing side walls of each socket 23 and 24 a short distance from the bottom of the slot to assist in retaining the shaft I2 in position at the ends of the slots. The shaft retaining cam faces are shown in FIG. 7. The shaft 12 is a tight friction fit in the

sockets

23 and 24 and serves as a reinforcement for the shell 11, tying the

side walls

14 and 15 together and substantially increasing the resistance of the shell to both compressive and bursting forces. It will also be noted that the shaft 12 is contained wholly within the shell 11 and the ends of the shaft are hidden.

The roller 13 is mounted on the shaft 12 as a slide fit before the shaft 12 is mounted in the

sockets

23 and 24 of the shell 11 and as can be seen from FIG. 6 the roller 13 comprises two

similar portions

29 and 30. Each

portion

29 and 30 of the roller comprises a smooth annular

outer face

31 and 32 respectively, a

flat end wall

33 and 34 respectively, a central

tubular portion

35 and 36 respectively, which is mounted on the shaft 12, and a plurality of internal

stiffening spokes

37 and 38 respectively.

The upper wall 18 of the shell 11 is also formed on its inside face with a plurality of ribs 40 which extend partly down the side walls and end walls and which stiffen and strengthen the shell further.

The bore 20 in the boss 19 is adapted to receive a pin 41, which is shown in FIG. 5, and which comprises a spigot 42 and'a bearing flange 43. The spigot 42 is a FIG. 6 is a section taken on the line VI-VI of FIG.

push fit into the bore 20 and the bore and spigot are formed with an interengaging rib 44 and groove 45 respectively which hold the spigot in place. The pin 41 serves as a means for mounting the castor 10 on the end of the leg of an article of furniture and the castor 10 is freely rotatable about the spigot 42 when the spigot is located in the borev 20.

It will be appreciated that any suitable type of fitting for mounting the castor on an article of furniture can be provided with a spigot for insertion in the bore 20 and the type of mounting shown in FIG. does not form a part of the present invention.

In an alternative form of the invention, a metal spigot can be permanently and non-rotatably moulded or bonded into the boss 19 so as to have a portion projecting upwardly from the boss. The upwardly projecting portion of the fixed spigot can then be inserted into a fitting on the end of a furniture leg to secure the castor rotatably to the leg.

As can be seen from FIG. 6 the end faces 33 and 34 of the two portions 29'and 30 of the roller 13 are a close fit between the inner faces of the enlarged

portions

21 and 22 of the side walls 14 and so that there is very little play between the roller 13 and the

sidev walls

14 and 15. The two

portions

29 and 30 of the roller 13 are thus held closely together although free to rotate in opposite senses orv together as required and any tendancy for dust or dirt to get into the roller or onto the shaft I2 is eliminated or at least substantially reduced. The close fit between'the shaft and the roller and between the end faces of the roller and the inside faces of the shell also substantially reduce the risk of hairs or similar strands from becoming wrapped around the ends of the shaft and interfering with the running of the roller.

- The roller is preferably formed from nylon or a material similar to that from which the shell is made and can either be moulded in two portions as shown in FIG. 1

to 8 or as a unitary member as shown in FIG. 8.

In FIG. 8 a castor is indicated generally at 50 which is similar to the fastener 10 of FIGS. 1 to 7 except in so far as it includes a unitary roller 51 mounted in a shell 52 which is substantially narrower than the shell 11 of the castor 10 to accommodate the unitary roller 51.

The unitary roller 51 can optionally be formed with an integral moulded outer surface 53 as shown in the lower half of the Figure, or alternatively it can be provided with an outer covering 54 as shown in the upper portion of the Figlire, the outer covering 54 being formed from a synthetic rubber material or foam polyurethane which is softer than the remainder of the roller and which is moulded in place onto the outside sur- Further minor modifications can be made to the above described embodiment without departing from the spirit and scope of the invention which is best described in the following claims.

What I claim is:

l. A castor comprising a hollow, unitary shell of synthetic plastics material open at the bottom and having two generally parallel laterally spaced side walls, an inner surface on each side wall formed with a vertical socket substantially T-shaped in cross section extending upwardly from the open bottom of the shell, integral restriction means spaced from the bottom of each socket, a shaft extending across said side walls provided with an annular groove adjacent each end forming end portions to fit saidv sockets between said restriction means and the socket bottom whereby movement of said shaft along said sockets is resisted by said restriction means so as to retain said shaft in position, said shaft positively'tying the side walls of the shell together and supporting same against compressive and twisting forces, a free running roller on said shaft, and vertical support means on said shell laterally offset from the axis thereof for mounting the shell pivotally on a supporting member.

2. A castor as claimed in claim 1, wherein said integral restriction means comprises cam faces in said socket walls.

3. A castor as claimed in claim 1, wherein said roller comprises two similar, unitary portions of synthetic plastics material independently rotatable on said shaft and completely filling the width and depth of said shell, said portions having flat closely arranged inner faces in sliding engagement with each other for militating against ingress of foreign matter therebetween, and exterior annular surfaces on said portions cooperatingly shaped to provide a convex rolling surface.

4. A castor as claimed in claim 3, wherein each roller portion comprises a flat outer wall and flat side walls on said shell arranged in close parallel juxtaposition to said flat outer walls respectively to minimize the entrance of foreign matter therebetween.

Claims

1. A castor comprising a hollow, unitary shell of synthetic plastics material open at the bottom and having two generally parallel laterally spaced side walls, an inner surface on each side wall formed with a vertical socket substantially T-shaped in cross section extending upwardly from the open bottom of the shell, integral restriction means spaced from the bottom of each socket, a shaft extending across said side walls provided with an annular groove adjacent each end forming end portions to fit said sockets between said restriction means and the socket bottom whereby movement of said shaft along said sockets is resisted by said restriction means so As to retain said shaft in position, said shaft positively tying the side walls of the shell together and supporting same against compressive and twisting forces, a free running roller on said shaft, and vertical support means on said shell laterally offset from the axis thereof for mounting the shell pivotally on a supporting member.