GB2372440A

GB2372440A - A braked castor

Info

Publication number: GB2372440A
Application number: GB0121290A
Authority: GB
Inventors: Stafford Screen; Kelvin Daniels
Original assignee: Guy Raymond Engineering Co Ltd
Current assignee: Guy Raymond Engineering Co Ltd
Priority date: 2001-02-26
Filing date: 2001-09-03
Publication date: 2002-08-28
Anticipated expiration: 2021-09-03
Also published as: GB0121290D0; GB0104734D0; GB2372440B

Abstract

A braked castor has a body 10 to which one or more wheels (16) is mounted, a stem (36) for fixing the castor to an article and being rotatable relative to the body, a carriage 62 which can slide relative to the body, and a pivotable actuator 92 for moving the carriage. In one condition of the sliding part and carriage the castor wheel and stem are free to rotate and in another condition at least one of these movements is locked and the actuator resists movement of the carriage from its locked position. The actuator may have a cam surface which co-operates with a corresponding formation on the carriage. The carriage may be spring-biassed to its free position. Locking may involve engagement of teeth 84,85 on the carriage with corresponding teeth on the stem and wheel respectively.

Description

A BRAKED CASTOR

The present invention relates to castors.

Castors generally comprise: a castor body; at least one wheel mounted for rotation relative to the castor body; and a stem for fixing the castor to an article, for example, an item of furniture, a hospital, institutional or educational apparatus, or a light industrial appliance. The stem may be mounted for rotation relative to the castor body.

In certain circumstances, it is desirable to brake free rotation of the wheel or wheels relative to the castor body, for instance to resist movement of the article to which the castor is fixed. It may be desirable to brake free rotation of the stem relative to the castor body to resist rotation, or swivelling, of the castor relative to the article.

It is an object of the present invention to provide an improved castor.

The present invention provides a castor comprising: a castor body; at least one wheel mounted for rotation relative to the castor body; a stem for fixing the castor to an article the stem being mounted for rotation relative to the castor body; a carriage mounted for generally linear sliding movement relative to the castor body; and an actuator mounted for pivotal movement relative to the castor body and for actuating movement of the carriage such that in a first condition of the carriage and the actuator said at least one wheel and said stem are free to rotate relative to the castor body and in a second condition of the carriage and the actuator rotation of one of said stem and said

at least one wheel is braked ; wherein in the second condition the actuator resists movement of the carriage out of the second condition.

Preferably, in the second condition the actuator prevents said generally linear sliding movement of the carriage.

Preferably, the carriage is biased towards the first condition and in the first condition resists movement of the actuator out of the first condition.

In the second condition of the carriage and the actuator rotation of said at least one wheel and said stem may be braked.

Said at least one wheel may be provided with a plurality of teeth which are engageable with a plurality of teeth provided on the carriage when the carriage and the actuator are in the second condition to brake free rotation of said at least one wheel.

Said plurality of teeth of said at least one wheel may be distributed circumferentially and said plurality of said teeth of said carriage may be arcuate to facilitate engagement with said plurality of teeth of said at least one wheel.

The stem may be provided with teeth which are engageable with teeth provided on the carriage when the carriage and the actuator are in the second condition to brake free rotation of said stem.

The stem teeth may be provided on a stem gear wheel rotationally fixed relative to the stem.

The actuator may comprise cam means cooperable with cam follower means provided on the carriage, pivotal movement of the actuator causing

sliding movement of the carriage to the first condition and to the second condition.

The carriage may comprise a first side piece fitted one side of the castor body and a second side piece fitted to an opposing side of the castor body, the side pieces having respective cam followers means cooperable with respective cam means provided on the actuator.

Each side piece may be provided with said teeth for engaging with said teeth of a respective said wheel.

Alternatively, the carriage may be one-piece and can be located on the castor body and secured thereto by mounting the actuator to the castor body.

Said at least one wheel may comprise a plurality of circumferentially distributed radially outwardly projecting teeth which are engageable with arcuately distributed teeth provided on the carriage, the teeth of the carriage being positioned in use between the actuator and said at least one wheel.

Biasing means may bias the cam follower means of the carriage to follow the cam means of the actuator.

In order that the present invention may be well understood, three embodiments thereof, which are given by way of example only, will now be described with reference to the accompanying drawings, in which: Figure 1 is a side view of a castor body; Figure 2 is a cross-sectional view of the castor body shown in Figure 1; Figure 3 is a side view of a castor wheel;

F*-ure 4 Figure 4 is a cross-sectional view of the wheel along the line IV-IV is a cross-sec i shown in Figure 3; Figure 5 is a side view of an actuator; Figure 6 is a side view of a spindle; Figure 7 is a side view of a stem; Figure 8 is a plan view of a stem gear wheel; Figures 9 and 10 are perspective views of a first side piece of a carriage ; Figures 11 and 12 are perspective views of a second side piece of the carriage ; Figures 13 and 14 are side views of the castor body shown only with the first side piece, biasing means, the stem and the stem gear wheel; Figure 15 is a cross-sectional view of the castor body and the stem gear wheel, the first side piece of the carriage and the actuator being superimposed for ease of explanation, in a second condition in which the stem is braked; Figure 16 is a cross-sectional view of the castor body and the stem gear wheel, the first side piece of the carriage and the actuator being superimposed for ease of explanation in a first condition in which the stem is not braked ; Figure 17 is a side view of a wheel, the first side piece of the carriage and the actuator in a first condition in which the wheel is free to rotate;

Figure 18 is a side view of a wheel, the first side piece of the carriage and the actuator in a second condition in which the wheel is braked ; Figure 19 is a cross-sectional view showing the stem and stem gear wheel fitted in the castor body; Figure 20 is an exploded view of a modified castor; Figure 21 is a side view of a castor body of a third castor; Figure 22 is a side view a wheel of the third castor; Figure 23 is a cross-sectional view of the wheel shown in Figure 22; Figure 24 is side view of a spindle of the third castor; Figures 25 and 26 show perspective views of a carriage of the third castor; Figures 27 and 28 show perspective views of an actuator of the third castor; Figure 29 is a side view of the castor body, carriage and actuator of the third castor in a first condition; and Figure 30 is a side view of the castor body, carriage and actuator of the third castor in a second condition.

Figures 1 to 12 show constituent parts of a castor. A castor body 10 shown in Figures 1 and 2, of a plastics material, for example type 6 nylon, or a metal, has a through passage 12 for receiving a spindle 14, of for example mild steel, shown in Figure 6. In the embodiment, two wheels 16 shown in Figures 3 and 4, of a plastics material, for example type 6 nylon, are mounted for rotation on respective end portions 18 of the spindle 14. It is possible

though to use only one wheel or more than two wheels depending on requirements. As illustrated, each wheel has a central boss 20 provided with a closed bore 22 into which the spindle end portion 18 extends. Each wheel 16 is axially retained on its respective spindle end portion 18 by interengagement of a groove 24 in the spindle end portion 18 and a rib 26 in the closed bore 22 of the central boss 20. More specifically each closed bore is formed with a radially inwardly projecting circumferentially extending rib which is received in an annular groove in the spindle end portion. A radially inwardly facing circumferential surface of each wheel is provided with a plurality of circumferentially distributed radially inwardly projecting teeth 28 for engagement with teeth of a carriage to brake free rotation of the wheel relative to the castor body. This will be described in greater detail below. A tyre 30, made from, for example polyurethane or thermoplastic rubber, is fitted to a radially outwardly facing circumferential flange 32 of the wheel.

The castor body 10 is provided with a through bore 34 and closed bore 35 which receives for rotation therein a metal stem 36, of for example mild steel, shown individually in Figure 7 and in position in Figure 19. The stem 36 is made up of a mount portion 38 for mounting to an article, for example, an item of furniture, a hospital, institutional or educational apparatus, or a light industrial appliance, and a central portion 40 which is received in through bore 34. An end portion 42, of smaller diameter than that of the central portion 40, is connected to the stem central portion 40 by a radially inwardly tapered portion 44. The stem 36 is axially retained in bores 34 and

I n 35 by interengagement of a groove 46 in the stem end portion 42 and a rib 48 in the closed bore 35 of the castor body 10. More specifically each closed bore is formed with a radially inwardly projecting circumferentially extending rib which is received in an annular groove in the stem end portion. However, other suitable means for retaining the stem in the castor may be adopted as appropriate. The stem central portion 40 and the stem end portion 42 are supported to allow rotation, or swivelling movement, of the stem relative to the castor body 10. As shown in Figures 2 and 19, stem end mates with a domed projection in closed bore 35 although instead a flat mating thrust surface may be adopted in the closed bore as preferred.

The stem end portion 42 extends through bore 55 in a stem gear wheel 54 (shown individually in Figure 8 and in position in Figure 19), of for example glass filled nylon 6, and is provided with two diametrically opposed axially extending ribs 50 which are received in respective axially extending grooves 52 in the stem gear wheel 54. Engagement of ribs 50 with respective grooves 52 prevents relative rotation between the stem and the stem gear wheel. The stem gear wheel is provided on a radially outwardly facing surface thereof with teeth 56 which project radially outwardly and which are engageable with teeth of the carriage to brake free rotation, or swivelling movement, of the stem relative to the castor body 10. It is convenient for assembly purposes to provide the stem with teeth 56 by way of a stem gear wheel although in some circumstances it may be preferred to provide teeth directly on the stem. The stem gear wheel sits in opening 58 in the castor

body 10 and is prevented from moving axially relative to the stem by contact between axially facing surfaces 59 and 60.

A carriage is shown in Figures 9 to 12 and comprises a first side piece 62 and a second side piece 64, each of for example glass filled nylon 6, which are connected together on opposed sides of the Castor body 10. Each side piece 62,64 has a respective aperture 63,65 through which the spindle extends. The carriage is supported on the castor body for generally linear sliding movement relative thereto. The first side piece 62 is provided with a spigot 66 having a through bore 68 for receiving fastening means for fastening the first side piece 62 to the second side piece 64. The fastening means may be a screw and in this case bore 68 may be threaded or alternatively the screw may be self-tapping so as to form a thread in bore 68 during insertion. Spigot 66 extends through opening 70 in the castor body (see Figure 2) and into a recess 72 in the second side piece where it is fastened by the fastening means (not shown). The fastening means is engaged in bore 73 which is preferably threaded if the fastening means is a screw. Alternatively, if the screw is selftapping the screw may form the thread in bore 73 during insertion. To permit sliding movement of the carriage relative to the castor body, opening 70 in the castor body is elongate to allow transverse movement of the spigot therein.

The spigot 66 is provided with a substantially flat surface 74 for cooperation with a biasing means which will be described below.

The first side piece 62 is provided with a laterally extending portion 76 having a through bore 78 for receiving fastening means for fastening the first

side piece 62 to the second side piece 64. The fastening means may be a screw and bore 78 may be threaded or alternatively the screw may be self tapping so as to form a thread in bore 78 during insertion. Laterally extending portion 76 extends through opening 58 in the castor body 10 (see Figure 2) and abuts surface 80 of the second side piece 64 where it is fastened by the fastening means (not shown). The fastening means is engaged in bore 82 which may be threaded if the fastening means is a screw. Alternatively, if the screw is self-tapping the screw may form the thread in bore 82 during insertion. To permit sliding movement of the carriage relative to the castor body, opening 58 is elongate to allow transverse movement of the laterally extending portion 76 therein. Opening 58 also accommodates stem wheel gear 54 and laterally extending portion 76 is provided with teeth 84 which are engageable with the teeth of the stem gear wheel to brake free rotation of the stem relative to the castor body.

Each side piece 62,64 is provided with a respective plurality of arcuate teeth 85 for engaging with the teeth 28 of a respective wheel to brake free rotation of the wheel. The respective plurality of teeth are arcuate to facilitate engagement with the circumferentially distributed teeth of respective wheels. Each side piece 62,64 is provided with cam follower means 91 in the form of a lobe which cooperate with cam means on an actuator to be described below.

An actuator 92, of for example glass filled nylon 6, is shown in Figure 5 and in Figures 15 to 18. A pivot means in the form of a metal shaft (not

shown) extends through a bore 94 provided in the actuator 92 and through a bore 96 in the castor body (see Figures 1 and 2) so that the actuator is supported on the castor body for pivotal movement relative thereto. The actuator is provided with cam means in the form of a cam lobe 98 which cooperates with cam follower means provided on the carriage (described in more detail below). A recess 99 provided in the actuator receives a cam follower means in a first condition of the actuator and carriage. A lever 100 is operable to pivot the actuator between its limits of travel.

Operation of the castor will now be described with reference particularly to Figures 13 to 18. Referring to Figures 13 and 14, the castor is shown from one side with spigot 66 and laterally extending portion 76 in view. Also shown is the stem 36 and stem gear wheel 54. Other components, including the second side piece 64, described above have been omitted in these Figures for clarity. Figure 13 shows a first condition of the carriage in which the wheels 16 and the stem 36 are free to rotate. Figure 14 shows a second condition of the carriage in which the wheels 16 and the stem 36 are braked. Obviously though Figures 13 and 14 show only the mechanism with

respect to braking rotation of the stem.

The castor is provided with biasing means in the form of a spring 86 which extends in an elongate recess 88 of the castor body. The biasing means extends between an abutment surface 89 of the recess 88 and surface 74 of the spigot 66 (see Figure 10) and is laterally enclosed by a wall of the castor body and a portion 90 of the second side piece 64 (see Figure 11). The biasing

means biases the carriage towards the first condition shown in Figure 13 in in which the teeth 84 of the laterally extending portion are spaced from the stem gear wheel 54. In Figure 14, the carriage is shown in the second condition in which the carriage has been moved against the bias of the biasing means 86 and teeth 84 of the laterally extending portion are engaged with the teeth 56 of the stem wheel gear to brake free rotation of the stem relative to the castor body.

Figures 15 and 16 illustrate the above operation of the carriage also showing operation of the actuator 92. Figure 15 shows the carriage and the actuator in the second condition and Figure 16 shows the carriage and the actuator in the first condition of the actuator 92 and the carriage with respect to one of the wheels 16. Again, only the components necessary for the explanation are shown for clarity.

In the first condition of the actuator 92 and carriage in Figure 16, teeth 84 of the carriage are spaced from teeth 56 of the stem gear wheel so that the stem is not braked and substantially free running is allowed. Obviously, though, some forces act against free rotation of the stem in this condition, such as friction of the stem in bores 34 and 15. The lever 100 of the actuator is in a substantially horizontal position with cam follower means, or lobe, 91 received in recess 99 of the actuator and the carriage in its right most position as viewed in Figure 16. Biasing means 86 (see Figures 13 and 14) biases the carriage to take up the first condition and lobe 91 is received in recess 99 thereby resisting pivotal movement of the actuator in the first condition.

Actuation of the carriage to the second condition is performed by moving lever 100 downwardly (a clockwise direction as viewed in Figure 16) about the pivot means. Lobe, or cam means, 98 moves upwardly cooperating with lobe 91 urging the carriage to slide towards the left as viewed in Figure 16 until the carriage and the actuator are in the second condition shown in Figure 15 where teeth 84 are engaged with teeth 56 thereby substantially braking free running of the wheel. In the second condition, movement of the carriage out of the second condition is resisted by the actuator 92 thus preventing disengagement of teeth 84 from teeth 56. More specifically, lobe 91 of the carriage acts on lobe 98 of the actuator along line A in Figure 15 which extends substantially through the pivot means of the actuator and the surface of lobe 98 is substantially square to lobe 91. This arrangement enables the actuator to prevent the generally linear sliding movement of the carriage when the actuator and carriage are in the second condition. The surface of lobe 98 abutting lobe 91 may be angled thereto to enhance this effect.

Lobe 98 may also be provided with a detent (not shown) for resisting movement of the actuator out of the second condition.

Activation of the carriage and the actuator to the first condition is performed by moving lever 100 upwardly (anti-clockwise as shown in Figure 15) allowing lobe 91 to slide under the bias of the biasing means 86 (towards the right as shown in Figure 15) into recess 99 to take up the first condition.

Figures 17 and 18 show the operation of the carriage and the actuator as above but with respect to braking rotation of the or each wheel. The actuator and carriage in Figure 17 are illustrated in a first condition in which teeth 85 are spaced from teeth 28 so that the wheel is not braked and substantially free running is allowed. Obviously, though, some forces act against free rotation of the wheel in this condition, such as friction of bore 22 about spindle end portion. The lever 100 of the actuator is in a substantially horizontal position with cam follower means 91 received in recess 99 of the actuator and the carriage in its right most position as viewed in Figure 17.

Biasing means 86 biases the carriage to take up the first condition.

Actuation of the carriage to the second condition is performed as above whereby lobe 98 moves upwardly cooperating with lobe 91 urging the carriage to slide towards the left as viewed in Figure 17 until the carriage takes up the position shown in Figure 18 in which the carnage and the actuator are in the second condition and teeth 85 are engaged with teeth 28 thereby substantially braking free running of the wheel. In the second condition, the actuator resists, as described above, movement of the carriage out of the second condition to resist disengagement of teeth 85 from teeth 28.

Activation of the carriage to the first condition is also as described above whereby lever 100 is moved upwardly (anti-clockwise as shown in Figure 18) allowing lobe 91 to slide under the bias of the biasing means 86 (towards the right as shown in Figure 18) to take up the first condition.

A presently preferred embodiment will now be descnbed with reference to Figure 20. Only the features which differ from the first embodiment will be discussed and like features will be given like reference numerals.

The castor 200 is provided with two wheels 202, each of which is provided with a through bore 204 in boss 206. The wheels 202 are mounted to the castor body 10 by a rivet 208, of for example mild steel, which extends through bores 204 and through bore 12 in the castor body 10. The wheels are axially retained on the rivet 208 by a flanged head 210 provided at one end portion of the rivet 208 and which abuts an axially outwardly facing surface of one of the wheels 202. The shank 212 is closed at an opposing end portion of the rivet 208 by a head (not shown) formed by hammering or other means and which abuts an axially outwardly facing surface of the other one of the wheels 202. The head may be rounded, flat or countersunk as preferred. A hub cap 214 is provided for each wheel 202.

The first side piece 62 and the second side piece 64 of the carriage are connected to each other and to the castor body 10 by fastening means which in this embodiment comprises two rivets 216,218, of for example mild steel. Rivet 216 extends through bore 220 in the first side piece 62, though opening 70 in the castor body 10 and through bore 222 in the second side piece 64 where it is closed by a head (not shown). Rivet 218 extends through bore 224 in the first side piece 62, through opening 58 in the castor body 10 and

through bore 226 in the second side piece 64 where it is closed by a head (not shown).

The actuator 92 is pivotally mounted to the castor body by a rivet 228, of for example mild steel, which extends through a bore 229 in the actuator 92, through bore 96 in the castor body 10, and through a second bore (not seen in Figure 20) in the actuator 92 where it is closed by a head (not shown).

A washer 232, of for example mild steel, may be provided to fit between the castor body and the article to which the castor is fixed.

In the drawings, the carriage is shown with two side pieces each being

rovi I provided with teeth for engaging with the teeth of a respective wheel. p However, alternative arrangements are possible. For example, teeth for engaging with the teeth of both wheels could be provided on only one of the side pieces or only one side piece may be provided.

Figures 21 to 30 show another castor. For brevity, only the features which differ from the first embodiment will be discussed and like features will be given like reference numerals. The most noticeable difference from the first embodiment is that the present embodiment does not allow for braking of the stem.

A castor body 310, shown in Figure 21, has a through passage 12 for receiving a spindle 314 shown in Figure 24. In the embodiment, two wheels 316 shown in Figures 22 and 23 are mounted for rotation on respective end portions 318 of the spindle 314. As illustrated, each wheel has a central boss 320 provided with a closed bore 322 into which the spindle end portion 318

extends. Unlike the first embodiment, each wheel 316 is axially retained on its respective spindle end portion 18 by interengagement of two grooves 324 in the spindle end portion 318 and two ribs 326 in the closed bore 322 of the central boss 320, respectively. Providing two grooves and two ribs reduces the possibility of accidental disengagement of the wheels from the spindle.

A radially outwardly facing circumferential surface of each wheel is provided with a respective plurality of circumferentially distributed radially outwardly projecting teeth 328 for engagement with teeth of a carriage to brake free rotation of each wheel relative to the castor body. This arrangement is different to that of the first embodiment in which the teeth of the wheels face radially inwardly. A tyre may be fitted to a radially outwardly facing circumferential portion 332 of the wheel.

The castor body 310 is provided with a closed bore 335 that receives for rotation therein a metal stem (not shown). The stem 335 is for mounting to an article, for example, an item of furniture, a hospital, institutional or educational apparatus, or a light industrial appliance and will not be described further in relation to this embodiment.

A carriage 360 is shown in Figures 25 and 26 and, unlike the first embodiment, is unitary (one-piece). The carriage is supported on the castor and is moveable forwards and backwards relative thereto (ie to the left and right as shown in Figures 29 and 30). Operation of the carriage will be described in greater detail below. The one-piece carriage is located on the castor body and secured thereto by mounting the actuator to the castor body.

This arrangement reduces manufacturing costs by decreasing the number of steps required in assembly since a separate step for securing the carriage to the castor body is not required. This is advantageous over the first embodiment in which respective screws or rivets are required to join the two side pieces of the carriage. It will be appreciated that in the first embodiment, the carriage is formed from two pieces to enable one piece (ie laterally extending portion 76) to extend through opening 58 of the castor body 10 and to be fastened to the other side piece thereby permitting teeth 84 to be positioned opposite the stem gear wheel.

The carriage has two elongate slots 362 opposed to each other for receiving respective side portions of a rib 364 which projects outwardly on both sides on the castor body 310. The slots 362 can slide on the rib 364 and support the carriage on the castor body for generally linear sliding movement relative thereto whilst substantially resisting movement of the carriage in any other direction. Once the actuator is mounted to the castor body, it limits movement of the carriage on rib 364 to prevent the carriage from becoming detached from the castor body.

The carriage 360 has two sets of a plurality of teeth 366 for engagement with teeth 328 of respective wheels 316. Each plurality of teeth 366 is distributed in an arc to facilitate engagement with the circumferentially distributed teeth 328 of respective wheels 316. The respective arcuate teeth 366 are positioned in use between the teeth 328 of respective wheels 316 and the actuator 392. This arrangement is possible because the teeth 328 of the

wheels project radially outwardly in this embodiment. With the arcuate teeth positioned in this way, it is possible to reduce the size of the carriage as compared with the first and second embodiments.

As will be described below the carriage is biased into a first condition shown in Figure 29 in which teeth 366 are disengaged from teeth 328 allowing the wheels 316 to rotate on spindle 314 relative to the castor body 310. Biasing means are provided in the form of a helical spring 368, shown in Figure 29, which is positioned in an elongate spring pocket 370 in the castor body As shown in Figure 21, the spring pocket 370 is closed on one side thereof and open on an opposing side thereof. The carriage 360 is provided with two arms 372 which are disposed either side of the castor body 310 and which help to guide the carriage on the castor body. When the carriage is in position on the castor body, one of the arms 372 partially closes the open side of the spring pocket 370 thus retaining the spring in the spring pocket as shown in Figures 29 and 30. The spring is compressed between an abutment end face 374 of the spring pocket and a spigot 375, shown in Figure 25, of the carriage.

The carriage is provided with cam follower means in the form of two cam followers, or lobes, 376 co-operable with respective cam means of an actuator 392, operation of which will be described in more detail below.

The actuator 392 is shown in Figures 27 and 28. A pivot means in the form of a metal shaft (not shown) extends through bores 394 provided in the actuator 392 and through a bore 396 in the castor body so that the actuator is

supported on the castor body for pivotal movement relative thereto as shown in Figures 29 and 30. The actuator is provided with cam means in the form of two cams, or lobes, 398 which cooperate with cam followers 376 provided on the carriage. Recesses 399 provided in the actuator receive cam followers 376 in a first condition of the actuator and carriage. Surfaces 400 and 402 of the carriage and the actuator, respectively, are arcuate (ie shaped to correspond with each other) so that the carriage and the actuator can fit against each other in the first condition. Spring 368 biases the carriage to take up the first condition and cam followers 376 are received in recesses 399 thereby resisting pivotal movement of the actuator in the first condition.

A lever portion 100 is operable to pivot the actuator between its limits of travel.

Operation of the castor is similar to the operation of the first embodiment in that the actuator 392 is pivoted to cause generally linear sliding movement of the carriage. However, in this embodiment only the wheels are braked and not the stem. Operation of this embodiment will be described with reference particularly to Figures 29 and 30 in which only the castor body 310, actuator 392, carriage 360 and spring 368 are shown. To

*de a f I provide a frame of reference, the position of the teeth of one of the wheels 316 is shown in broken lines.

The first, or unbraking, condition of the actuator 392 and carriage 360 is shown in Figure 29. In the first condition, the teeth 366 of the carriage are spaced from teeth 328 of the wheels 316 so that the wheels are not braked and

substantially free running is allowed. The lever 100 of the actuator is in a substantially horizontal position with cam followers 376 received in recesses 399 of the actuator and surfaces 400 and 402 fitting against each other. In the first condition, spring 368 is relatively uncompressed.

The lever portion 100 is operable downwardly to pivot the actuator 392 anti-clockwise as shown. This pivotal movement causes cams 398 to cooperate with cam followers 376 to slide the carnage to the right, as shown, so that teeth 366 of the carriage engage with teeth 328 of the wheels as shown in Figure 30. This generally linear sliding movement of the carriage acts against the bias provided by the spring which in Figure 30 is relatively compressed.

Once in the second condition, movement of the carriage out of the second condition is resisted by the actuator 392 thus preventing disengagement of teeth 366 from teeth 328. More specifically, cam followers 376 of the carriage act on cams 398 of the actuator along line B in Figure 30 which extends substantially through the pivot of the actuator and the surfaces of cams 398 are substantially square to cam followers 376. This arrangement enables the actuator to prevent the generally linear sliding movement of the carriage when the carriage and the actuator are in the second condition.

Activation of the carriage and the actuator to the first condition is performed by moving lever 100 upwardly (clockwise as shown in Figure 30) allowing the carriage to slide under the bias of the spring 368 (towards the left as shown in Figure 30) so that the actuator and the carriage take up their first condition. According to the embodiments shown, in the second condition, rotation of the wheels are braked. However, it may be desirable for only the stem to be braked in the second condition according to requirements.

Claims

1. A castor comprising : a castor body ; at least one wheel mounted for rotation relative to the castor body; a stem for fixing the castor to an article the stem being mounted for rotation relative to the castor body; a carriage mounted for generally linear sliding movement relative to the castor body; and an actuator mounted for pivotal movement relative to the castor body and for actuating movement of the carriage such that in a first condition of the carriage and the actuator said at least one wheel and said stem are free to rotate relative to the castor body and in a second condition of the carriage and the actuator rotation of one of said stem and said at least one wheel is braked; wherein in the second condition the actuator resists movement of the carriage out of the second condition.

2. A castor as claimed in claim 1 wherein in the second condition the actuator prevents said generally sliding linear movement of the carriage.

3. A castor as claimed in claim I or 2 wherein the carriage is biased towards the first condition and in the first condition resists movement of the actuator out of the first condition.

4. A castor as claimed in any one of the preceding claims, wherein in the second condition of the carriage and the actuator rotation of said at least one wheel and said stem are braked.

5. A castor as claimed in any one of the preceding claims, wherein said at least one wheel is provided with a plurality of teeth which are engageable with a plurality of teeth provided on the carriage when the carriage and the actuator are in the second condition to brake free rotation of said at least one wheel.

6. A castor as claimed in claim 5, wherein said plurality of teeth of said at least one wheel are distributed circumferentially and said plurality of said teeth of said carriage are arcuate to facilitate engagement with said plurality of teeth of said at least one wheel.

7. A castor as claimed in any one of the preceding claims, wherein the stem is provided with teeth which are engageable with teeth provided on the carriage when the carriage and the actuator are in the second condition to brake free rotation of said stem.

8. A castor as claimed in claim 7, wherein the stem teeth are provided on a stem gear wheel rotationally fixed relative to the stem.

9. A castor as claimed in any one of the preceding claims, wherein the actuator comprises cam means cooperable with cam follower means provided on the carriage, pivotal movement of the actuator causing said generally linear sliding movement of the carriage to the first condition and to the second condition.

A

10. A castor as claimed in any one of the preceding claims, wherein the carriage comprises a first side piece fitted one side of the castor body and a second side piece fitted to an opposing side of the castor body, the side pieces having respective cam followers cooperable with respective cams provided on the actuator.

11. A castor as claimed in claim 10, wherein each side piece is provided with a plurality of said teeth for engaging with a plurality of said teeth of respective ones of two wheels mounted on respective sides of the castor body.

12. A castor as claimed in claim 1, wherein the carriage is one-piece and can be located on the castor body and secured thereto by mounting the actuator to the castor body.

13. A castor as claimed in claim 1 or 12, wherein the at least one wheel comprises a plurality of circumferentially distributed radially outwardly

projecting teeth which are engageable with arcuately distributed teeth 01 1provided on the carriage, the teeth of the carriage being positioned in use between the actuator and said at least one wheel.

14. A castor as claimed in any one of the preceding claims, wherein biasing means biases the cam follower means of the carriage to follow the cam means of the actuator.

15. A castor substantially as hereinbefore described with reference to Figures 1 to 19; Figures 1 to 19 as modified by Figure 20; or Figures 21 to 30 of the accompanying drawings.