GB2204484A

GB2204484A - Castor

Info

Publication number: GB2204484A
Application number: GB08711164A
Authority: GB
Inventors: George Stanton Beswick; Eric Ramsbottom
Original assignee: HILBAR PLASTICS Ltd
Current assignee: HILBAR PLASTICS Ltd
Priority date: 1987-05-12
Filing date: 1987-05-12
Publication date: 1988-11-16
Also published as: GB8711164D0

Abstract

A castor has a body (10), a support (11) rotatable relative to the body (10) about a castor axis (27) and a wheel assembly (12) rotatable relative to the support (11) about a rolling axis (26), a brake member (29) being moveable, relative to the support (11) into and out of positive braking relationship with the wheel assembly (12). The brake member (29) can rotate with the wheel assembly (12) about the castor axis (27) and be longitudinally moveable by an actuator (15) stationary relative to the castor axis. <IMAGE>

Description

CASTOR This invention relates to a castor, and in particular to a castor having a brake for its wheel.

Heretofore, there have been proposed many castors incorporating brakes for wheels thereof. A known braking arrangement includes a brake pad which in its "on" position is urged into frictional contact with the wheel. Such an arrangement has the disadvantage that wear of the arrangement and/or of the wheel can cause the braking force to decrease, possibly eventually to zero. In any case, wear of a frictional pad makes maintenance essential. In the case of many known brake arrangements, the brake has to be applied by foot pressure on a pedal and the brake pressure depends on the foot pressure. This can lead to strained mechanisms and to uneven application pressures. An additional disadvantage is that brake mechanisms often rotate with the wheel about its castor axis.This can mean that the position of an operating pedal rotates around the castor axis and may be inaccessible or difficult to reach.

An object of the present invention is to provide a castor wherein one or more of the above disadvantages are obviated or reduced.

The invention provides a castor having a body, a support rotatable relative to the body about a castor axis, and a wheel assembly rotatable, relative to the support, about a rolling axis, a brake member being movable, relative to the support, into and out of positive braking relationship with the wheel assembly.

The invention also provides a castor having a body, a support rotatable relative to the body about a castor axis, and a wheel assembly rotatable, relative to the support, about a rolling axis, a brake member being movable, relative to the support, into and out of braking relationship with the wheel assembly by an actuator which is fixed against rotation with the support.

The invention additionally provides a castor having a body, a support rotatable relative to the body about a castor axis, and a wheel assembly rotatable, relative to the support, about a rolling axis, a brake member being movable, relative to the support, into and out of braking relationship with the wheel assembly by an actuator which includes a bistable pedal having an won" position and an "off" position, the pedal being biassed towards the "on" position.

The wheel assembly can simply be a wheel rotatable about an axle fixed to the support and having a formation with which the brake member can positively engage.

Alternatively the wheel assembly can be a wheel with an axle fixed to it and journalled in bearing(s) on the support, the axle having a formation for engagement by the brake member.

There can be a plurality of formations, such as teeth, on the wheel assembly, and one or more teeth or recesses on the brake member.

The castor axis will usually be upright, ie vertical or at some angle to the verti'cal, the rolling axis normally being horizontal or close to horizontal.

The support can have a circular-sectioned plug received in a circular socket in the body, or can have a socket which engages a plug of the body. The body can be adapted for securement to structure such as a trolley leg or the like.

The support can be a clevis mounting the wheel assembly between its plates and having a shaft engaging the body of the castor.

The brake member can also be a clevis riesting within the support and movable axially of the support clevis shaft, the brake member clevis shaft having means for engagement by an actuator relative to which it is rotatable about the castor angle.

The plates of the brake member clevis can have respective forks each having a blind recess which is slidably engaged with a tooth formation on the wheel assembly, the blind end of the recess having one or more teeth complementary to the teeth on the wheel assembly formation.

The actuator can include a T-shaped member disposed between spaced plates extending radially outwards from the castor body. The T-shaped member can be pivoted near the upper end of the upright of the T, have one end of the cross-piece engaged with the shaft of the brake member clevis and have the other end of the cross-piece forming a pedal.

The lower end of the upright of the T can have a detent mechanism rendering it bistable and a spring can bias the lower end of the upright outwards towards an "on" condition.

The invention will be described further, by way of example, with reference to the accompanying drawings, wherein Fig. 1 is a vertical cross-sectional view through a preferred castor of the invention; and Fig. 2 is a cross section on line II-II of Fig. 1.

A preferred castor of the invention comprises a body 10, a support 11, a wheel assembly 12 (including a wheel 13 and axle 14) and an actuator 15.

Body 10 has (considered in its use position) an upper cylindrical plug 16 which can fit within a lower end of a tubular trolley leg or the like 17 shown in dotted lines in Fig. 1. Alternatively, the body 10 can have a flange whereby it can be attached by fasteners or can have any other desired form. Body 10 has a downwardly open cylindrical aperture 18 into which projects a shank 19 of support 11.

Shank 19 has a peripheral groove 20 and a setscrew 21 retains shank 19 captive but rotatable. A pair of cheek plates 22 extend generally radially outwards from body 10 one on each side of a slot 23 in the wall of body 10. Cheek plates 22 sandwich a lever 24 of actuator 15.

Support 11 is in the form of a clevis (Fig. 2) having shank 19 and plates 25 which have bearing apertures for axle 14 of the wheel assembly 12.

The axis of axle 14 is the rolling axis 26 and Fig. 2 shows clearly how axis 26 is offset from castor axis 27 (axis of shank 19) to give the castor action. A thrust bearing 28 is arranged between the lower end of body 10 and the upper surface of support 11.

Support 11 is hollow and nesting within it is a brake member 29 also in the form of clevis having a shaft 30 axially slidable within shank 19 and parallel fork flanges 31 guided by ribs 32 slidable in grooves 33 in plates 25.

Each flange 31 is arched having a central blind slot 34 having a single tooth formation 35. Wheel assembly 12 includes pinion-shaped formations 36 one on each side of the wheel 13 and integrally formed with the wheel 13.

Flanges 31 are positioned to allow teeth formations 35 to move into and out of engagement with pinions 36 to achieve positive lock braking of the wheel 13.

The upper end of shaft 30 has an annular encircling groove 37 which a fork 38 enters and can raise or lower shaft 30 out of and into a braking condition, independently of the rotational position of the shaft 30.

Actuator 15 consists of plates 22 which sandwich T-shaped lever 24 which is pivoted at 39 near the top of its upright 45. The right hand end of its cross piece is constituted by forks 28 and the left hand end by a pedal 40.

The lower end of the upright 45 carries a transverse cylindrical pin 41 which bridges plates 22 and slides on cam surfaces 42 into and out of detents 43. This arrangement makes the lever 24 bistable, both positions being shown in Fig. 1. A compression spring 44 urges the lower end of the upright 45 to the left in Fig. 1, thus urging forks 38 and brake members 29 towards the braked position.

In the castor of the invention, the braking action is a positive locking braking, in that formations 26 and 35 interlock and are spring biassed towards that condition. The user must make a positive action against the action of the spring to remove the brake.

The position of the actuator lever is fixed at all times and can be arranged to be convenient for actuation. Its position does not rotate with the support.

The invention is not limited to the details- of the foregoing and variations can be made thereto. For example the wheel assembly could be cantilevered from a single limbed support, and the brake element would have a single limb in this case.

Claims

I. A castor having a body, a support rotatable relative to the body about a castor axis, and a wheel assembly rotatable, relative to the support, about a rolling axis, a brake member being movable, relative to the support, into and out of positive braking relationship with the wheel assembly.
2. A castor having a body, a support rotatable relative to the body about a castor axis, and a wheel assembly rotatable, relative to the support, about a rolling axis, a brake member being movable, relative to the -support, into and out of braking relationship with the wheel assembly by an actuator which is fixed against rotation with the support.
3. A castor having a body, a support rotatable relative to the body about a castor axis, and a wheel assembly rotatable, relative to the support, about a rolling axis, a brake member being movable, relative to the support, into and out of braking relationship with the wheel assembly by an actuator which includes a bi-stable pedal having an "on" position and an "off" position, the pedal being biassed towards the "on" position.
4. A castor as claimed in claims 1 to 3 wherein the wheel assembly is a wheel rotatable about an axle fixed to the support and having a formation with which the brake member can positively engage.
5. A castor as claimed in claims 1 to 3 wherein the wheel assembly is a wheel with an axle fixed'to it and journalled in bearing(s) on the support, the axle having a formation for engagement by the brake member.
6. A castor as claimed in claims 1 to 5, wherein there is a plurality of formations, such as teeth, on the wheel assembly, and one or more teeth or recesses on the brake member.
7. A castor as claimed in any of claims 1 to 6, wherein the castor axis is upright, i.e. vertical or at some angle to the vertical, the rolling axis normally being horizontal or close to horizontal.
8. A castor as claimed in any of claims 1 to 7, wherein the support has a circular-sectioned plug received in a circular socket in the body, or has a socket which engages a plug of the body.
9. A castor as claimed in any preceding claim wherein the body is adapted for securement to structure such as a trolley leg or the like.
10. A castor as claimed in any of claims 1 to 7, wherein the support is a clevis mounting the wheel assembly between its plates and having a shaft engaging the body of the castor.
11. A castor as claimed in any of claims 1 to 10, wherein the brake member is a clevis nesting within the support and movable axially of the support clevis shaft, the brake member clevis shaft having means for engagement by an actuator relative to which it is rotatable about the castor angle.
12. A castor as claimed in claim 11, wherein plates of the brake member clevis have respective forks each having a blind recess which is slidably engaged with a tooth formation on the wheel assembly, the blind end of the recess having one or more teeth complementary to the teeth on the wheel assembly formation.
13. A castor as claimed in claim 11, wherein the actuator includes a T-shaped member disposed between spaced plates extending radially outwards from the castor body.
14. A castor as claimed in claim 13, wherein the T-shaped member is pivoted near the upper end of the upright of the T, has one end of the cross-piece engaged with the shaft of the brake member clevis and has the other end of the cross-piece forming a pedal.
15. A castor as claimed in claims 13 or 14 wherein the lower end of the upright of the T has a detent mechanism rendering it bistable and a spring biasses the lower end of the upright outwards towards an "on" condition.
16. A castor substantially as hereinbefore described with reference to the accompanying drawings.