GB2047364A

GB2047364A - Improvements in or relating to devices for arresting movement of castor wheels

Info

Publication number: GB2047364A
Application number: GB8009384A
Authority: GB
Original assignee: Blickle Heinrich Co KG GmbH
Current assignee: Blickle Heinrich Co KG GmbH
Priority date: 1979-03-26
Filing date: 1980-03-20
Publication date: 1980-11-26
Also published as: DE2911850C2; IT1127001B; CH642596A5; ATA138080A; GB2047364B; NL8001534A; FR2452389A1; AT375588B; DE2911850A1; IT8048239A0; FR2452389B1

Abstract

A device for arresting movement of a castor wheel 5 comprises a locking lever 15 pivotable downwards in the direction indicated by arrow 26, whereby a cam surface 14 on the lever 15 is caused to bear against a reaction surface 24 of a stationary wall portion 8. Upon further downward movement of the locking lever 15, a slider 11 is displaced axially as indicated by arrow 25 whereby a wedge surface 18 on a solid member 20 increases the bias force of a leaf spring 17 until the spring is caused to press against the periphery of the wheel 5 to arrest rotation thereof, and until a disc 3 attached to a fork member 4, 4<1> locating the wheel 5 is arrested by projections 19 so as to prevent pivoting of the fork member. As shown, solid member 20 and projections 19 (on plate 22) are screwed to slider 11; alternatively surface 18 and projections 19 can be pivotally mounted to slider 11; alternatively projections 19 and slider 11 can form an integral unit. <IMAGE>

Description

SPECIFICATION Improvements in or relating to devices for arresting movement of castor wheels This invention relates to devices for arresting movement of a castor wheel.

The invention is particularly concerned with foot-operated devices operable to arrest rotary and pivotal mobility of a castor wheel which is rotatably mounted in the limb portions of a fork member provided with a vertical pivot axis, wherein there is provided a pivotally mounted locking lever which can be depressed, thereby moving beyond a dead centre position, against the force of a leaf spring which can be brought into contact with the periphery of the wheel, which locking lever also co-operates with a disc rigidly connected to the pivot axis. Devices of this kind are known (German Patent Specification No.1,505,759).

In the known device, the locking lever is mounted with clearance (slots) on a mounting shaft which is fixed with respect to the fork member, and the locking lever is provided with a projection which can be adjusted towards the periphery of the roller, while the disc which is rigidly connected to the pivot axis is provided with a cone member which is coaxial to the pivot axis of the disc and with which there cooperates a further leaf spring which is operatively connected to the locking lever and which is provided with a counter-cone member. In addition, there is a bridge member which is adjustably connected to the mounting end of the locking lever and which has a limb portion bearing against the locking lever, the bridge member also being operatively connected by means of a projection to the leaf spring associated with the wheel.Both leaf springs are fixedly connected to the fork member only at one position and can be moved into their locking condition, thereby being spread. Although the known castor wheel device has proved to be satisfactory, the locking lever must be actuated with a comparatively large amount of force. Thus the present invention is based on the problem of further developing the known castor wheel device in such a way that a comparatively high force can be applied by means of a comparatively low adjusting force, in order thereby to prevent the wheel from rotating and the castor wheel fork member from pivoting.

According to one aspect of the present invention, a device which is connectible to a castor wheel and which in particular is footoperated, for blocking the rotary and pivotal mobility of the wheel which is rotatably mounted in the limb portions of a fork member provided with a vertical pivot axis, wherein there is provided a pivotally mounted locking lever which can be depressed, thereby moving beyond a dead centre position, against the force of a leaf spring which can be brought into contact with the periphery of the wheel, which locking lever also co-operates with a disc rigidly connected to the pivot axis, is characterised in that a guide means which is of Ushaped cross-section and which is provided with a transverse wall portion is secured to the castor wheel fork member, and a slider is guided between the limb portions of the guide means and the sides of the transverse wall portion, the slider at its trailing end which is disposed outside the limb portions of the fork member carrying the mounting means of the locking lever which is provided with slide cam means or with a slide surface, while at its other end which is between the limb portions of the fork member, besides wedge surface which bears against the leaf spring secured to the guide means, the slider carries two projections which are spaced from each other and which can be brought into contact with the periphery of the disc which is rigidly connected to the pivot axis, wherein the transverse wall portion is secured to the guide means in such a way that the slide cam means or the slide surface of the locking lever bear against the transverse wall portion during the major part of the pivotal movement of the locking lever.

It is desirable for the spacing of the projections which are secured directly or indirectly to the slider to be negligibly smaller than the diameter of the disc which is rigidly connected to the pivot axis because this arrangement makes it possible to exert the maximum force for blocking the pivotability of the castor wheel fork member.

Although it is sufficient for the slider and.the projections to be in the form of a one-piece unit, it is desirable for the projections to be releasably secured to the slider, in order to be able to compensate for wear symptons. By virtue of this arrangement, after releasing a plate carrying the projections, it is possible for example to insert, between a surface of the slider and the abovementioned plate, a piece of sheet metal whose thickness approximately corresponds to the wear which has occurred. Obviously, the plate bearing the projections may also be replaced by another plate, after a certain degree of wear on the projections.

In addition, it is desirable for the wedge surface to be fixed adjustably in the direction of movement of the slider in order to compensate for wear thereof, particularly when the wedge surface is a surface of a wedge member which is secured to the slider. However, it is also possible for the wedge surface and the projections or the plate bearing the projections to be mounted pivotally with respect to the slider, because in that case the leaf spring which acts on the wedge surface pivots the wedge surface and the projections in such a way as to compensate for wear which occurs.

According to another aspect of the present invention, a device for arresting movement of a castor wheel which is rotatably mounted in the limb portions of a fork member provided with a vertical pivot axis, comprises a pivotally mounted locking lever which can be depressed, thereby moving beyond a dead centre position, against the force of a leaf spring which can be brought into contact with the periphery of the wheel so as to arrest rotatable movement thereof, and a slidable membei, also operable by pivotable movement of the locking lever, for arresting rotational movement of the fork member about said pivot axis.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, wherein: Figure 1 is a side view, partly in section, of a castor wheel and its arresting device, with the device in the released condition, Figure 2 is an underneath view in section, taken along line Il-Il of Figure 1, with parts of the castor wheel removed, Figure 3 is a side view corresponding to Figure 1, but showing the arresting device in the locking position, Figure 4 is a view in section, taken along line IV-lV of Figure 3, Figure 5 is a view looking in the direction of thearrow V of Figure 1, with the device in the arresting condition, and Figure 6 is a plan view of part of Figure 5.

With reference to Figures 1, 2, 4, 5 and 6, for securing the castor wheel 5 to an article which is required to move, the assembly has a fixing plate 1 with a centre pin 2 rigidly connected thereto at the centre thereof. The centre pin 2 comprises the pivot axis for the castor wheel 5 and is integral with a plate or disc 3. A fork member with a horizontally extending web portion 4 and limb portions 41 which rotatably carry the castor wheel 5 in the limb portions is pivotal about the pin 2, and is mounted by way of rolling bearing rings (not shown) with respect to the fixing plate 1 and the disc 3 respectively. A guide means 7 of "U-shaped cross-section is secured to the web portion 4 of the fork member 4, 41 by screws 6 with nuts. A transverse wall portion 8 is secured between the limb portions 71 of the guide means 7, by means of screws 9 with nuts.A slider 11 is arranged to be guided in the guide means 7 between the limb portions 71 thereof and outside parts 10 of the transverse wall portion 8. At its trailing end 12, which is disposed outside the limb portions 41 of the fork member, the slider 11 carries a pin 13 which comprises the mounting means of the locking lever 1 5. The lever 1 5 is provided at one end with slide cam means in the form of a slide surface 14.At the other end 1 6 of the slider 11, which end is disposed between the limb portions 41 of the fork member, besides a wedge surface 1 8 which bears against a leaf spring 1 7 secured to the guide means 7, the slider 11 carries two projections 1 9 (Figure 5) which are spaced from each other and which can be brought into contact with the periphery of the plate 3.The transverse wall portion 8 is secured to the guide means 7 in such a way that the slide cam surface 1 4 of the locking lever 1 5 lies against the transverse wall portion 8 during the major part of the pivotal movement of the locking lever 1 5. As can be seen from Figures 2 and 4, tabs 8' which are integral with the transverse wall portion 8 extend over the spaces above the outsides 10 of the transverse wall portion 8, being the spaces in which the slider 11 is guided between the limb portions 71 of the guide means 7.

In the embodiment illustrated, the wedge surface 18 is the inclined surface of a solid member 20 which in cross-section forms a kind of wedge which is secured to a transverse web portion 111 of the slider 11 by means of screws 21. At the same time, the screws 21 secure a plate 22 with which the projections 1 9 are integral (see Figures 5 and 6). The spacing "a" between the projection 1 9 is negligibly smaller than the diameter "d' of the plate 3 which is rigidly connected to the pivot axis of the shaft 2.

The slider 11 and the projections 19 can be in the form of an integral unit. it is more desirable however, as assumed in the embodiment illustrated, for the projections 1 9 to be releasably secured to the slider 11. However, the wedge surface 1 8 and the projections 19 can also be mounted pivotally with respect to the slider 1 , for example by the screws 21 being mounted in slots which extend in a vertical direction, which was not shown.

When the components of the device are in the positions shown in Figures 1 and 2, the wheel 5 can turn freely about its mounting 23 and the wheel 5 can pivot about the pivot axis of the centre pin 2, depending on the forces acting on the vehicle. If, irrespective of the position of the fork member 4, 41, the locking lever 15 is pivoted downwardly in the direction indicated by arrow 24, for example, by operation of the foot, the slide cam means or surface 14 of the lever bears against the facing reaction surface 24 of the transverse wall portion 8. Upon further pivotal movement of the locking lever 1 5, the slider 11 is then displaced with respect to the guide means 7 in the direction indicated by arrow 25 whereby the wedge surface 1 8 increases the bias force of the leaf spring 17 until the leaf spring 17 comes to bear against the periphery of the wheel 5 (see Figure 3). As, during this pivotal movement of the locking lever 15, the two projections 1 9 also move towards the periphery of the disc or plate 3 and finally bear there-against (see Figure 6), the fork member 4, 41 is also fixed with respect to the fixing plate 1, by way of the disc or plate 3, so that the wheel is prevented from rotating and from pivoting.

Claims

1. A device which is connectible to a castor wheel and which in particular is foot-operated, for blocking the rotary and pivotal mobility of the wheel which is rotatably mounted in the limb portions of a fork member provided with a vertical pivot axis, wherein there is provided a pivotally mounted locking lever which can be depressed, thereby moving beyond a dead centre position, against the force of a leaf spring which can be brought into contact with the periphery of the wheel, which locking lever also cooperates with a disc rigidly connected to the pivot axis, characterised in that a guide means which is of "U"-shaped cross-section and which is provided with a transverse wall portion is secured to the castor wheel fork member, and a slider is guided between the limb portions of the guide means and the sides of the transverse wall portion, the slider at its trailing end which is disposed outside the limb portions of the fork member carrying the mounting means of the locking lever which is provided with slide cam means or with a slide surface, while at its other end, which is between the limb portions of the fork member, besides a wedge surface which bears against the leaf spring secured to the guide means, the slider carries two projections which are spaced from each other and which can be brought into contact with the periphery of the disc which is rigidly connected to the pivot axis, wherein the transverse wall portion is secured to the guide means in such a way that the slide cam means or the slide surface of the locking lever bear against the transverse wall portion during the major part of the pivotal movement of the locking lever.

2. A device according to Claim 1, characterised in that the spacing between the projections is negligibly less than diameter of the disc which is rigidly connected to the centre pin.

3. A device according to Claim 1, characterised in that the slider and the projections are in the form of a one-piece unit.

4. A device according to Claim 1 or Claim 2, characterised in that the projections are releasably secured to the slider.

5. A device according to Claim 1 or Claim 2, characterised in that the wedge surface is secured to the slider so as to be adjustable in the direction of movement thereof.

6. A device according to Claim 1, characterised in that the wedge surface and the projections are mounted pivotally with respect to the slide.

7. A device for arresting movement of a castor wheel which is rotatably mounted in the limb portions of a fork member provided with a vertical pivot axis, comprising a pivotally mounted locking lever which can be depressed, thereby moving beyond a dead centre position, against the force of a leaf spring which can be brought into contact with the periphery of the wheel so as to arrest rotatable movement thereof and a slidable member, also operable by pivotable movement of the locking lever, for arresting rotational movement of the fork member about said pivot axis.

8. A device for arresting movement of a castor wheel, substantially as hereinbefore described with reference to the accompanying drawings.