GB2441303A

GB2441303A - Castor

Info

Publication number: GB2441303A
Application number: GB0617106A
Authority: GB
Inventors: Martin Lee Harris; Richard John Spencer
Original assignee: Colson Castors Ltd
Current assignee: Colson Castors Ltd
Priority date: 2006-08-31
Filing date: 2006-08-31
Publication date: 2008-03-05
Also published as: GB0617106D0

Abstract

A castor having a castor body, a connection assembly for connecting the castor body to a device, such that the castor body is able to swivel with respect to the connection member about a swivel axis which is substantially upright, at least one castor wheel supported by the castor body for rotation about a wheel axis which is substantially perpendicular to the swivel axis and offset therefrom, a locking means operable in a first mode for preventing swivelling movement of the castor body relative to the connection member, and operable in a second mode for preventing swivelling movement of the castor body relative to the connection member and for inhibiting rotation of the at least one wheel relative to the castor body, wherein the locking means includes first and second locking members respectively engageable with first and second locking formations, when the locking means is operated in the first and second modes.

Description

Title: Castor

Description of Invention

This invention relates to a castor. Castors in accordance with the present invention are intended particularly, but not exclusively, for use on beds, patient trolleys and the like for hospitals and other premises.

It is conventional practice for a bed for use in hospitals and the like to be provided with four castors, one at each corner of the bed. Each castor has at least one ground-engaging castor wheel rotatable about an axis which is generally horizontal. The wheel or wheels are carried by a support structure which can swivel relative to its connection to the bed, about a swivel axis which, when the castor is in use, is generally vertical, and which is offset from the horizontal axis about which the wheel or wheels can rotate.

A castor for a hospital bed or the like is required to be able to have its wheel(s) braked, at least to resist, or preferably completely prevent their rotation about the horizontal axis. It is also a requirement to be able to prevent the castor from swivelling about its swivel axis. Such braking of the wheel(s) and prevention of swivelling may be required to be effected together, a condition generally, and herein, referred to as total lock'.

There is also so called direction lock' where the castor wheel(s) are locked in a particular orientation, usually longitudinally of the bed, such that they are prevented from swivelling, but are still able to rotate. This enables the bed to be controlled more easily when being pushed or pulled in fore and aft directions.

An aim of the present invention is to provide a castor with an improved locking mechanism, particularly an improved swivel lock mechanism.

According to the present invention, we provide a castor having a castor body; a connection member for connecting the castor body to a device, such that the castor body is able to swivel with respect to the connection member about a swivel axis which is substantially upright; at least one castor wheel supported by the castor body for rotation about a wheel axis which is substantially perpendicular to the swivel axis and offset therefrom; and a locking means operable in a first mode for preventing swivelling movement of the castor body relative to the connection member, and operable in a second mode for preventing swivelling movement of the castor body relative to the connection member while at least inhibiting rotation of the at least one wheel relative to the castor body; wherein the locking means includes first and second locking members respectively engageable with first and second locking formations, when the locking means is operated in the first and second modes.

The locking members may be carried by the castor body.

The first and second locking formations may be provided in an abutment member which is connected to the connection member and prevented from rotating with respect to the connection member so that the abutment member is prevented from rotating relative to the device to which it is connected.

The abutment member may be hollow.

The locking means may further include a braking member which, when the locking means is operated in the second mode, effects braking of the at least one castor wheel relative to the castor body.

The first and second modes of the locking means may be operable by actuating means carried by the castor body.

The actuating means may comprise a foot pedal.

The actuating means may be moveable in a first direction from a starting position to operate the locking means in the first mode.

The actuating means may be moveable in a second direction from the starting position which is substantially opposite the first direction to operate the locking means in the second mode.

The actuating means may include at least one lever which moves the first and second locking members in accordance with movement of the actuating means by an operator.

The foot pedal may comprise a three-position rocker pedal.

The first and second formations may each include at least one recess.

The first locking formation may comprise two recesses, each of which corresponds to an orientation of the castor which is parallel to the longitudinal direction of the device to which it is connected.

The second locking formation may comprise a plurality of recesses to enable directional locking of the castor in one of a plurality of angular positions.

The first and second locking members may each include a first part which is engageable with a locking formation and a second part which is moveable by the actuation means.

The first and second parts may be spring biased relative to one another to control the position of the first part relative to the second part.

The first part may be receivable inside the second part.

The spring may be inside the second part, such that the extent to which the first part extension is received in the second part is controlled by the extension and contraction of the spring.

The first and second locking members may be generally cylindrical.

The braking member may be engageable with tooth formations provided on the at least one castor wheel.

The braking member may include a bar carried by the at least one lever.

The castor may have two wheels disposed with at least a part of the castor body, which is provided with the locking members, between them.

An embodiment of the invention will now be described, by way of example only, with reference to the following drawings, in which: FIGURE 1 is a perspective cut away view of a castor according to the present invention, showing the locking means located internally of the castor body, FIGURE 2 is a perspective cut away view of a castor according to the current invention, showing the relationship between the castor body and the locking means, FIGURE 3 is a side view of a castor according to the present invention in its neutral position, FIGURE 4 is a side view of a castor according to the present invention showing the locking means in a first mode of operation, and FIGURE 5 is a side view of a castor according to the present invention, showing the locking means in a second mode of operation.

Referring to the figures, a castor according to the present invention is shown generally at 10. The castor 10 has a castor body 12, and two castor wheels 14, only one of which is shown. The castor wheels 14 are mounted on an axle 16 for rotation about a substantially horizontal axis relative to the castor body 12. The castor 10 also has a connection member indicated generally at 18 which enables the castor 10 to be connected to a device, such as a hospital bed or trolley (not shown).

The castor body 12 extends between the castor wheels 14 and includes a generally cylindrical cover part 12a which houses a locking means, the axle 16, and part of an actuation means 33 which is operable to actuate the locking means. The castor body 12 also includes a boss 13 which extends generally upwardly of the castor body 12 towards the device to which the castor 10 is to be connected.

The castor 10 is connected to a device (not shown) by means of a connection member 18 and the boss part 13. The connection member 18 is generally cylindrical and has a first part 18a which is positioned at the top of the connection member 18. The first part 18 comprises a generally hexagonal portion which is provided with a central aperture 18b which extends downwardly through the connection member 18. The connection member 18 is connected to a device by means of inserting an attachment member (not shown) into the central aperture 18b of the connection member 18 and a part of the device, for example the leg of a hospital bed. In this example, the connection member 18 extends inside the boss 13 and carries bearings whose outer races are received in the boss 13, to enable the castor body 12 to swivel with respect to the connection member 18 about a substantially vertical axis B. The locking means of the castor 10 includes an abutment member 20 which is positioned below and carried by the first part 18a of the connection member 18. The abutment member 20 in this example is a hollow, cylindrical sleeve 20, having the rolling element bearings at each of its ends. The abutment member is oriented such that its longitudinal axis is aligned with the axis of rotation B, although it is not permitted to swivel with respect to the connection member 18 and thus nor is permitted to swivel relative to the device to which the castor is attached.

The locking means further includes first and second locking members 22, 23 which are carried by the castor body 12 and are movable by an actuation means 33 for engagement respectively with first and second locking formations 25, 26 of the abutment member 20. In this example, the first and second locking members 22, 23 are cylindrical and each has a first part 22a, 23a and a second part 22b, 23b. The first parts 22a, 23a are received in the respective second, outer parts 22b, 23b. Each inner part 22a and 23a protrudes from a longitudinal end of the corresponding outer part 22b, 23b, and is engageable respectively with the first and second locking formations 25, 26.

The first locking formation 25 includes a first recess 25 and a second recess (not shown), which are diametrically opposed to one another and located near to one of the longitudinal ends of the sleeve 20. In the present example, the first locking formation 25 is positioned in an upper region of the sleeve 20.

The second locking formation 26 includes 12 recesses, which are regularly spaced around the circumference of the sleeve 20, towards the opposite longitudinal end of the shaft to the first locking formation 25.

It will be apparent to one skilled in the art that the locking formations 25, 26 may be apertures which extend from the exterior of the sleeve 20 to the hollow interior rather than recesses if desired. It will also be apparent that the second locking formation 26 may include any number of recesses or apertures 26.

The inner parts 22a, 23a are spring biased outwardly of the outer parts 22k, 23b. Each of the outer parts 22b, 23b houses a spring (not shown) one end of which is connected to the inner part 22a, 23a of the locking member 22, 23 and the other end of which is connected to the corresponding outer part 22b, 23b, such that extension of the spring causes a smaller portion of the inner part 22a, 23a to be received in the outer part 22a, 23a, and contraction of the spring causes a larger portion of the inner part 22a, 23a to be received in the outer portion 22b, 23b.

Each of the first and second locking members 22, 23 is provided with a means of holding the locking member 22, 23 in a position in which it is set. The first and second locking members 22, 23, are provided with grooves 48, with which a detent member (not shown) is engageable, to retain each locking member 22, 23 in one of a number of desired positions. It will be apparent that any means of detent may be used as required.

Each of the outer parts 22b, 23b of the first and second locking members 22, 23 is provided with an aperture (not shown), towards its end remote from the abutment member 20. Each of the apertures is elongate, which enables each of the first and second locking members 22, 23 to be connected to an actuating means 33 via connectors, for example pins.

The actuating means 33 is carried by the castor body 12. The actuating means 33 includes a rocker foot pedal 33a which is external of the castor body 12 such that it is accessible to an operator, and which is moveable from a central, neutral position, into one of two operational positions for actuating the locking means. The actuating means 33 further includes two lever members 36, 36b, which extend from the foot pedal 33a into the interior of the castor body 12.

Each lever member 36a, 36b is provided with a first aperture 38 for mounting the actuating means on an axle 34, which allows the actuating means to pivot about a substantially horizontal axis with respect to the castor body 12. The lever members 36a, 36b are connected for operation of the first and second locking members 22, 23 by pins which extend through apertures 31, 31b, 32a, 32b in the lever members 36a, 36b, and through the apertures 3O, 30b of the first and second locking members 22, 23.

The lever members 36a, 36b, are each provided with a third aperture 4O, 40b, through which a braking member 42 is positioned. In this example, the braking member 42 comprises a bar which is engageable with an engagement formation 44. The engagement formation 44 includes a disk which is carried by the wheel 14, and has a plurality of teeth 44 protruding from its circumference for engagement with the braking member 42 in order to inhibit rotation of the braking member 42 and the castor wheels 14 with respect to the castor body 12.

The castor 10 is also provided with at least one sweeper member 46, which depends from the castor body 12 towards the ground when the castor 10 in use. The sweeper member 46 is flexible, and in this example includes a spring.

The castor 10 has three general modes of operation. When the actuating means 33 is in its central neutral position, as shown in Figure 3, the first and second locking members 22, 23 are not engaged with the locking formations 25, 26 and the castor wheels 14 are allowed to rotate relative to the castor body 12 about the axle 16. The castor body 12 is also permitted to swivel about the substantially vertical axis B to facilitate turning of the device to which the castor 10 is connected. In this mode of operation, the inner parts 22a, 23a of the first and second locking members 22, 23 protrude from the outer parts 22b, 23b and there is clearance between each of the inner parts 22, 23a and the sleeve 20. The braking member 42 is not engaged with the braking formation 44, therefore the castor wheels 14 are permitted to rotate with respect to the castor body 12 about axle 16. As the device is moved, the castor 10 travels in its first mode and the sweeper member 46 operates to move obstacles from the path of the castor 10 as it travels. The sweeper member 46 is positioned such that there is only a small distance between the end of the sweeper member 46 and the floor in order that the sweeper member 46 encounters obstacles, such as cables lying in the path of the castor 10, before the obstacles are encountered by the castor wheels 14.

A first mode of operation of the locking means is shown in Figure 4. The actuating means 33 has been moved into a first locking position by an operator applying pressure to the foot pedal 33a in a first direction, which in this example is generally upwards. Moving the actuating means 33 into the first locking position causes the lever members 36a, 36b to rotate about the axle 34 in a first direction. The movement of the lever members 36a, 36b in the first direction causes the first locking member 22 to be moved towards the sleeve 20. At the same time, the second locking member 23 moves away from the sleeve 20. The inner part 22a of the first locking member 22 comes into contact with the upper part of the sleeve 20 and, depending on the rotational position of the castor body 12 with respect to the sleeve 20, will either be aligned with a recess 25a, 25b of the first locking formation, or will be aligned with a part of the sleeve 20 which is not recessed. In the first situation, the inner part 22a engages with the first locking formation 25 and in the second situation the inner part 22a retracts into the outer part 22b, compressing the spring in the first locking member 22, such that as soon as the castor body has rotated into a position where the inner part 22 is aligned with one of the recesses 25a, 25b, the spring extends and pushes the inner part 22a into engagement with the recess 25a, 25b. In this mode of operation, the castor wheels 14 are permitted to continue to rotate with respect to the castor body 12, whilst the castor body 12 is prevented from swivelling with respect to the device to which the castor 10 is connected. This swivel lock' mode of operation of the locking means is preferable when the device to which the castor 10 is connected is being moved in a generally straight line, for example along a corridor, and it is desired to retain the castor 10 in alignment with the device.

The first locking formation 25 of the castor 10 includes two recesses 25, 25k such that the castor 10 may be locked against swivelling in one of two positions. The recesses 25a, 25b are diametrically opposed such that the castor 10 may be locked parallel to the longitudinal direction of the device to which it is connected, in one of a leading or trailing orientation. A leading orientation is one in which the castor body 12 is ahead of the connection member 18 in the direction that the device is travelling, and a trailing orientation is one in which the castor body 12 follows the connection member 18. It will be appreciated that it is possible to provide a first locking formation having only one recess or aperture, which would provide one locked orientation of the castor 10, or that it would be possible to provide a greater number of apertures, thus increasing the number of possible swivel lock orientations.

A second operation mode of the locking means, which provides total lock', is shown in Figure 5. The actuating means 33 has been moved into a second locking position by an operator applying pressure to the foot pedal 33 in a second direction which, in this example, is generally downwards. Moving the actuating means 33 into the second locking position causes the lever members 36a, 36k to be rotated about the axle 34 in a second direction. The movement of the lever members 36a, 36b in the second direction causes the second locking member 23 to be moved towards the sleeve 20. At the same time the first locking member 22 is moved away from the sleeve 20, increasing the clearance between the inner part 22a of the first locking member 22 and the sleeve 20. The inner part 23a of the second locking member comes into contact with the lower part of the sleeve 20 and, depending on the rotational position of the castor body 12 with respect to the sleeve 20, will either be aligned with a recess 26 of the second locking formation 26, or will be aligned with a part of the circumference of the sleeve 20 which is not recessed. In the latter situation, the spring contracts, retracting the inner part 23 of the second locking member 23 into the outer part 23b, until such time as the inner part 23a is aligned with one of the recesses of the second locking formation 26, and the spring is able to extend such that the inner part 23a engages with the second locking formation 26.

In the present example the second locking formation 26 includes 12 recesses, spaced at 30 centres around the circumference of the sleeve 20 such that when the locking means is in its second mode of operation, rotating the castor body 12 a maximum of 15 in either direction will cause the second locking member 23 to align with one the recesses of the second locking formation 26, preventing further swivelling movement of the castor body 12 with respect to the device to which the castor 10 is connected.

The second mode of operation of the locking means also engages the braking member 42 with the engagement formation 44. As the lever members 36a, 36b are rotated in the second direction, the bar 42 engages the teeth 44a which protrude from the disk 44. The engagement of the bar 42 with the teeth 44a, inhibits rotation of the castor wheels 14 with respect to the castor body 12, to provide braking of the castor 10. It is possible for the rotation of the castor wheels 14 to be slowed or prevented completely. Hence in the second mode of operation of the locking means, the castor 10 is prevented from swivelling about substantially vertical axis B, whilst the rotation of the castor wheels 14 with respect to the castor body 12 about substantially horizontal axis A is inhibited or prevented such that the castor 10 exhibits total lock'.

This mode of operation of the locking member is preferable when it is required to retain the device to which the castor 10 is connected in a stationary position.

It will be apparent that any number of castors 10 may be connected to a device and operated separately or collectively in the modes described above in order to control the movement of the device.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS

1. A castor having a castor body; a connection member for connecting the castor body to a device, such that the castor body is able to swivel with respect to the connection member about a swivel axis which is substantially upright; at least one castor wheel supported by the castor body for rotation about a wheel axis which is substantially perpendicular to the swivel axis and offset therefrom; and a locking means operable in a first mode for preventing swivelling movement of the castor body relative to the connection member, and operable in a second mode for preventing swivelling movement of the castor body relative to the connection member while at least inhibiting rotation of the at least one wheel relative to the castor body; wherein the locking means includes first and second locking members respectively engageable with first and second locking formations, when the locking means is operated in the first and second modes.

2. A castor according to claim 1 wherein the locking members are carried by the castor body.

3. A castor according to claim 1 or claim 2 wherein the first and second locking formations are provided in an abutment member which is connected to the connection member and prevented from rotating with the respect to the connection member so that the abutment member is prevented from rotating relative to the device to which the castor is connected.

5. A castor according to claim 3 or claim 4 wherein the abutment member is hollow.

6. A castor according to any of the preceding claims wherein the locking means further includes a braking member which, when the locking means is operated in the second mode, effects braking of the at least one castor wheel relative to the castor body.

7. A castor according to any one of the preceding claims wherein the locking means are operable by an actuating means carried by the castor body.

8. A castor according to claim 7 wherein the actuating means comprises a foot pedal.

9. A castor according to claim 7 or 8 wherein the actuating means is moveable in a first direction from a starting position to operate the locking means in the first mode.

10. A castor according to claim 9 wherein the actuating means is moveable in a second direction from the starting position which is substantially opposite the first direction to operate the locking means in the second mode.

11. A castor according to any one of claims 7 to 10 wherein the actuating means includes at least one lever which moves the first and second locking members in accordance with movement of the actuating means by an operator.

12. A castor according to any one of claims 8 to 11 wherein the foot pedal comprises a three-position rocker pedal.

13. A castor according to any one of the preceding claims wherein the first and second locking formations each include at least one recess.

14. A castor according to any one of the preceding claims wherein the first locking formation comprises two recesses, each of which corresponds to an orientation of the castor which is parallel to the longitudinal direction of the device to which it is connected.

15. A castor according to any one of the preceding claims wherein the second locking formation comprises a plurality of recesses to enable directional locking of the castor in one of a plurality of angular positions.

16. A castor according to any one of the preceding claims wherein the first and second locking members each include a first part which is engageable with a locking formation and a second part which is moveable by the actuation means.

17. A castor according claim 16 wherein the first and second parts are spring biased relative to one another, to control the position of the first part relative to the second part.

18. A castor according to claim 16 or claim 17 wherein the first part is receivable inside the second part.

19. A castor according to claim 18 wherein the spring is inside the second part, such that the extent to which the first part extension is received in the second part is controlled by the extension and contraction of the spring.

20. A castor according to any one of the preceding claims wherein the first and second locking members are generally cylindrical.

21. A castor according to any one of claims 6 to 20 wherein the braking member is engageable with tooth formations provided on the at least one castor wheel.

22. A castor according to claim any one of claims 7 to 18 wherein the braking member includes a bar carried by the at least one lever.

23. A castor according to any one of the preceding claims having two wheels disposed with at least a part of the castor body, which is provided with the locking members, between them.

24. A castor substantially as described herein and/or with reference to the accompanying drawings.

25. Any new feature or combination of features described herein and/or in the accompanying drawings.