US3751757A

US3751757A - Swivel castors, particularly for shopping trolleys

Info

Publication number: US3751757A
Application number: US00149600A
Authority: US
Inventors: H Stosberg; H Fleischmann; G Reinhards; S Engels
Original assignee: Tente Rollen GmbH and Co
Current assignee: Tente Rollen GmbH and Co
Priority date: 1971-02-06
Filing date: 1971-06-03
Publication date: 1973-08-14
Anticipated expiration: 1990-08-14
Also published as: JPS5127331B2; JPS4844940A; DE2105547A1; CA929307A; FR2123980A5; GB1333533A; BE778257A; JPS5127332B1; SE359498B; IT946818B

Abstract

A swivel castor for use on appliances such as shopping trolleys, which are conveyed on a ribbed or grooved conveyors comprises a castor fork with a running wheel and a tracking wheel arranged for rotation with and on the same axle as the running wheel. The tracking wheel is movable vertically in respect of the running wheel so that when the appliance is placed on the conveyor the tracking wheel can drop into a groove thereof. While the castor is running on a flat floor the tracking wheel hold a locking mechanism in inoperative position. When the tracking wheel drops into a groove the locking mechanism locks the wheel against running movement. The locking mechanism also includes a vertically movable member which follows the downward movement of the tracking wheel to lock the castor against swivelling movement. The latter member may be a pawl which engages ratchet teeth on the backset bearing or in an incision or groove in the castor fork. The vertical movement of the member can be controlled by the periphery of the tracking wheel or by an upper extension of the bearing disc of the tracking wheel.

Description

United States Patent [191 Stosberg et al.

[451 Aug. 14, 11973 SWIVEL CASTORS, PARTICULARLY FUR SHOPPING TROLLEYS [75] Inventors: Herbert Stosberg; Horst Fleischmann, both of Wermelskirchen-Tente, Rhineland; Giinter Reinhards, Wermelskirchen/Rhineland; Siegfried Engels, Wermelskirchen-Tente, Rhineland, all of Germany [73] Assignee: Tente-Rollen Gesellschatt Mit Beschrankter Haftung Companie, Wermelskirchen-Tente ap Rhineland, Germany [22] Filed: June 3, 1971 [211 App]. N0.: 149,600

[30] Foreign Application Priority Data Feb. 6, 1971 Germany P 21 05 547.0

[52] US. Cl. 16/35, 188/5 [51] Int. Cl B60b 33/00 [58] Field of Search 16/35, 35 D; 188/5, 188/32 [56] References Cited UNlTED STATES PATENTS 3,305,064 2/1967 Mullis et a1. 188/5 3,608,693 9/1971 Stosberg et al. 16/35 Primary Examiner-James T. McCall Assistant Examiner-Doris L. Troutm an Attorney-Burgess, Dinklage & Sprung [57] ABSTRACT A swivel castor for use on appliances such as shopping trolleys, which are conveyed on a ribbed or grooved conveyors comprises a castor fork with a running wheel and a tracking wheel arranged for rotation with and on the same axle as the running wheel. The tracking wheel is movable vertically in respect of the running wheel so that when the appliance is placed on the conveyor the tracking wheel can drop into a groove thereof. While the castor is running on a flat floor the tracking wheel hold a locking mechanism in inoperative position. When the tracking wheel drops into a groove the locking mechanism locks the wheel against running movement. The locking mechanism also includes a vertically movable member which follows the downward movement of the tracking wheel to lock the castor against swivelling movement. The latter member may be a pawl which engages ratchet teeth on the backset bearing or in an incision or groove in the castor fork. The vertical movement of the member can be controlled by the periphery of the tracking wheel or by an upper extension of the bearing disc of the tracking wheel.

17 Claims, 20 Drawing Figures PATENIE AL"; 1 4 8973 sum 03 0F 10 PAIENIEW 1 3,751,757

SHEET 07 HF 10 PAIENIEU we 1 41975 SHEET 08 0F 10 SWIVEL CASTORS, PARTICULARLY FOR SHOPPING TROLLlEY The invention relates to a swivel castor, intended particularly for use with shopping trolleys in self-service stores, where passage from one floor to another is effected by way of stairs or moving stairways, which are ribbed so that self-service customers using the stairs or moving stairways can take their shopping trolleys with them. The invention can however also be used for industrial or other purposes where it is desired to convey mobile appliances on ribbed conveyor belts.

In order that shopping trolleys can be taken along without danger in self-service stores even on conveyor belts or moving stairways ribbed in this manner, it is known to lock the swivel castors or other castors of the shopping trolley, in respect of the running mobility of their running wheels, during the period in which it is taken along on the conveyor path, until the castors reach a guard plate at the end of the conveyor belt and arrive again on a level floor. For this purpose all the castors, or individual castors, of the shopping trolley are each provided with a vertically movable sensing member in continuous contact with the floor and when the sensing member dips into a groove in the conveyor belt a locking mechanism is actuated which locks the running wheel in such a way as to prevent it running, as is described and illustrated in connection with a multiplicity of forms of embodiment in German Gebrauchsmuster No. 67 51 035 and in US. Pat. No. 3608693 (US. Pat. application Ser. No. 814 961) for which the application was filed on the th Apr. 1969.

In a particularly favourable form of embodiment such automatically self-locking castors take the form of a swivel castor with a vertically movable sensing member in the form of a conjointly running sensor wheel which is arranged parallel to the running wheel and located together. with the running wheel on the axle of the running wheel and which therefore follows the movements of the running wheel on a parallel track, for which reason it will be termed in what follows a tracking wheel. The said tracking wheel conjointly rotating parallel to the running wheel is however vertically movable in relation to the running wheel axis and hence relatively to the running wheel. This means that the tracking wheel rotating conjointly parallel to the running wheel is in continuous contact with the floor and when passing in transition on to the ribbed conveyor stretch can dip into a groove in the conveyor belt or moving track. As a result of this sinking movement the tracking wheel conjointly rotating as a sensing member releases a locking mechanism which brakes the running wheel in respect of its running mobility. This means that the swivel castors and hence the shopping trolley remain locked during entrainment on the conveyor stretch until, at the end of the ribbed conveyor belt, the lowered tracking wheels are raised again out of the grooves of the conveyor belt by its guard plate.

'With such swivel castors, which possess a vertically movable sensing member in the form of a vertically movable tracking wheel conjointly rotating parallel to the running wheel and on the running wheel axle, a disc-shaped tracking wheel dipped into a groove of a conveyor belt or other travelling platform provides a sufficiently strong lateral holding power for the swivellably movable per se swivel castor, if the ribbed travelling platform consists of metal, for instance light metal sectional elements, so that then the swivel castors cannot swivel during entrainment on the conveying stretch. For some time however travelling platforms with rubber sectional elements have been used. However, the comparatively soft rubber ribs of such travelling platforms do not give sufficient lateral hold to the conjointly rotating disc-shaped tracking wheel acting as vertically movable sensing member after the dipping into a groove in the rubber belt, so that there is a danger of the swivel castors inadvertently swivelling during the entrainment on the conveying stretch and hence it is possible for the shopping trolley or the like to escape sideways, which might cause an accident.

An object of the invention is to avoid this disadvantage and to make such swivel castors as possess a vertically movable sensing member in the form of a vertically movable tracking wheel conjointly rotating parallel to the running wheel and on the running wheel axle, also safely usable for such ribbed moving platforms and conveyor belts as consist of rubber sectional elements or other soft material and which do not give sufficient lateral holding strength against swivelling to the tracking wheels after the dipping into the grooves in the conveyor belt.

The novel swivel castor for mobile appliances to be entrained or conveyed on ribbed or grooved conveyor belts, which castor is particularly designed for shopping trolleys in self-service stores and which has a vertically movable sensing member in the form of a vertically movable tracking wheel conjointly rotating parallel to the running wheel and on the running wheel axle, which tracking wheel is in continuous contact with the floor and which on dipping into a groove of the conveyor belt releases a locking mechanism locking the running mobility of the running wheel, is characterised in accordance with the basic idea of the invention in that the swivel castor also has a vertically movable locking member controlled by the conjointly rotating tracking wheel, for additionally locking the swivelling mobility of the castor fork, which vertically movable locking member is continuously raised when the conjointly rotating tracking wheel is travelling over a level floor and remains raised, and when the conjointly rotating tracking wheel dips into a groove in the conveyor belt than the vertical movement of the conjointly rotating tracking wheel can follow and thereby it can sink into its locking position and thus can effect the lockin of the castor fork. v

The control of the vertically movable locking member, which serves for the additional locking of the swivelling mobility of the castor fork, can be effected from the conjointly rotating tracking wheel in any suitable manner. In an advantageous form of embodiment of the invention the vertically movable locking member is controlled and raised by a bearing disc of the conjointly rotating tracking wheel. For this purpose the bearing disc of the conjointly rotating tracking wheel can have an upper extension, which controls and raises the locking member. Even simpler and more advantageous is a form of embodiment of the invention in which the vertically movable locking member is simply applied on the periphery of the conjointly rotating tracking wheel and is thereby lifted and lowered by the wheel periphcry.

The vertically movable locking member which is controlled by the conjointly rotating tracking wheel and serves for the additional locking of the swivelling mobility of the castor fork, may be of any suitable type and construction. In an advantageous form of embodiment of the invention the vertically movable locking member takes the form of a locking pawl which engages in the catch or locking position as the conjointly rotating tracking wheel sinks down, and is released again from its catch (locking) position as the conjointly rotating tracking wheel rises again.

Particular advantages are offered by a modification of the basic idea of the invention, which is characterised in that the pawl, which is controlled by the conjointly rotating tracking wheel and serves for additionally locking the swivelling mobility of the castor fork, is supported in the hollow of the castor fork and as the conjointly rotating tracking wheel sinks can engage in stationary ratchet teeth on the swivel castor rear or back-set bearing, thereby also locking the swivelling mobility of the castor fork. In an advantageous form of embodiment of this modification of the invention the pawl is supported by one end on a spindle in the fork hollow. In another form of embodiment of this modification of the invention the pawl takes the form of a two-armed lever which is supported on a spindle in the fork hollow.

In order that the vertically movable locking pawl can follow the vertical movement of the conjointly rotating tracking wheel as it dips in, the said pawl can be springloaded, the spring pressing the pawl downwards and the pawl being raised against its pressure when travelling over a level floor by the conjointly rotating tracking wheel.

The vertically movable pawl controlled by the conjointly rotating tracking wheel, for additionally locking the swivelling mobility of the castor fork, which is preferably supported in the hollow of the said castor fork, simply lies, in an especially simple form of embodiment on the periphery of the conjointly rotating tracking wheel and can thus follow its sinking and rising movement. Advantageously the pawl is applied by a projection of noise-reducing elastic material on the periphery of the conjointly rotating tracking wheel. In another form of embodiment the pawl lies on an upper extension of the bearing disc of the conjointly rotating tracking wheel and can thus follow its sinking movement. The pawl can however also be articulately connected with the upper extension of the bearing disc of the conjointly rotating tracking wheel in any suitable manner in such a way that the pawl is compelled to follow the vertical movement of the conjointly rotating tracking wheel.

In another form of embodiment of the invention the vertically lowerable pawl which is controlled by the conjointly rotating tracking .wheel, is not a constituent of the castor fork, but instead is supported on the fixed swivel castor rear or back-set bearing and can then lockingly engage in an incision or groove or the like in the castor fork, in order to lock this additionally in respect of its swivelling mobility, as a result of the sinking movement of the conjointly rotating tracking wheel. For this purpose the bearing disc of the conjointly rotating tracking wheel can be made with an upper extension of suitable form, which during travel over a level floor closes the ratchet type incision of the swivel castor fork and when the tracking wheel sinks, frees the fork incision for the catch engagement of the pawl, which thus as the conjointly rotating tracking wheel dips in a groove of the conveyor belt additionally locks the swivelling mobility of the swivel castor fork.

In a further form of embodiment of the invention there is supported in the swivel castor back-set bearing a vertically displaceable catch pin, which is provided with a lower locking disc, secured against twisting or rotation, that is to say in such a manner that when travelling over a level floor the catch pin is continuously held by the conjointly rotating tracking wheel in its top dead centre position, and when the conjointly rotating tracking wheel sinks, the catch pin sinks with it and can thereby engage by means of its lower locking disc in ratchet teeth provided in the hollow of the castor fork, so that through the sinking of the conjointly rotating tracking wheel the swivel castor fork is also additionally locked. In order to ensure that the vertically displaceable catch pin acting as locking member follows the vertical movement of the conjointly rotating tracking wheel and is controlled by this, the bearing disc of the conjointly rotating tracking wheel can be formed with an upper extension and a bracket applied against this, on which the vertically displaceable catch pin is applied by its lower end and maintains continuous contact by its own weight.

In the drawings are diagrammatically represented some examples of embodiment of the invention.

FIG. 1 is a partly cut away view of a swivel castor with a locking pawl applied on the tracking wheel and supported at one end, freely movable on a level floor.

FIG. 2 is a view, likewise partly cut away, of the freely-movable swivel castor of FIG. I viewed in the direction of travel.

FIG. 3 corresponds to FIG. 1 and shows the swivel castor fully locked on a grooved conveyor belt, with the tracking wheel dipped into a conveyor belt groove.

FIG. 4 corresponds to FIG. 2 and shows the fully locked swivel castor of FIG. 3 viewed in the direction of travel.

FIG. 5 is another partly cut away view of a swivel castor with a locking pawl supported at one end and controlled by the ball bearing disc of the tracking wheel, freely movable on a level floor.

FIG. 6 is also a partly cut away view of the freely movable swivel castor of FIG. 5 viewed in the direction of travel.

FIG. 7 corresponds to FIG. 5 and shows the swivel castor completely locked on a grooved conveyor belt,

with the tracking wheel dipped into a conveyor belt groove.

FIG. 8 corresponds to FIG. 6 and shows the completely locked swivel castor of FIG. 7 viewed in the direction of travel.

FIG. 9 is another partly cut away view of a swivel castor with a locking pawl formed as a two-armed lever and controlled by the ball bearing disc of the tracking wheel, freely movable on a level floor.

FIG. 10 is also a partly cut away view of the freely movable swivel castor of FIG. 9 viewed in the direction of travel.

FIG. 11 corresponds to FIG. 9 and shows the swivel castor completely locked on a grooved conveyor belt, with the tracking wheel dipped in to a conveyor belt groove.

FIG. 12 corresponds to FIG. 10 and shows the completely locked swivel castor of FIG. 11 viewed in the direction of travel.

FIG. 13 is a partly cutaway view of a swivel castor with a locking pawl supported in the fixed swivel castor back-set or rear bearing, freely movable on a level floor.

FIG. 14 is a partly cut away view of the freely movable swivel castor of FIG. 13 viewed in the direction of travel.

FIG. 15 corresponds to FIG. 13 and shows the swivel castor completely locked on a grooved conveyor belt with the tracking wheel dipped into a conveyor belt groove.

FIG. 16 corresponds to FIG. 14 and shows the completely locked swivel castor of FIG. 15 viewed in the direction of travel.

FIG. 17 is another partly cut away view of a swivel castor with a catch pin provided with a locking disc and displaceable in the swivel castor back-set or rear bearing, freely movable on a level floor.

FIG. 18 is a partly cut away view of the freely movable swivel castor of FIG. 17 viewed in the direction of travel.

FIG. 19 corresponds to FIG. 17 and shows the swivel castor completely locked on'a grooved conveyor belt, with the tracking wheel dipped into a conveyor belt groove.

FIG. 20 corresponds to FIG. 18 and shows the com pletely locked swivel castor of FIG. 19 viewed in the direction of travel.

The swivel castors illustrated are designed for shopping trolleys in self-service stores, which trolleys can be entrained on ribbed or grooved conveyor belts. They have therefore a vertically movable sensing member in the form of a tracking wheel 3 conjointly rotating parallel to the running wheel 1 and on the running axle 2. The tracking wheel 3 is however movable in the vertical direction in relation to the running wheel axle 2.

As can be seen from the cut away drawings in FIG. 4 and FIG. 12, the tracking wheel 3 in these examples of embodiment is rotatably supported for this purpose bilaterally between two

ball bearing discs

4 and 5, which have a substantially larger bore 6 than the wheel hub 7 and are therefore movable vertically in respect of the running wheel axle 2 and hence relatively to the running wheel 1. The two

ball bearing discs

4 and 5 are force-lockingly connected to one another by an annular intermediate component 8. The outer ball bearing disc 5 is vertically movably guided by a cam 9 in a slot 10 of the castor fork 11, which cam 9 prevents the wheel body of the tracking wheel 8, which wheel body consists of the

ball bearing discs

4 and 5 and the intermediate component 8, from rotating on the hub 7 round the running wheel axle 2. A pressure spring 12 accommodated in the hollow wheel body presses the wheel body downwards and ensures that the tracking wheel 3 is continuously in contact with the floor and is urged to sink deeper beyond the periphery of the run ning wheel 1. The tracking wheel 3 is made so narrow at its periphery 13 that when travelling over a grooved conveyor belt 14 it can sink into one of the grooves 15, being urged to do so by the pressure spring 12. When such a dipping into a groove 15 of the conveyor belt 14 takes place, the tracking wheel 3 releases a locking mechanism locking the running mobility of the running wheel 1. This locking mechanism consists, in the examples of embodiment represented, of a pin 16 provided at the inner ball bearing disc 4, and of pocket-shaped ratchet notches 17 which are provided round the pe riphery of the wheel body 18 of the running wheel 1. As the disc-shaped wheel body of the tracking wheel 3, which wheel body consists of the

ball bearing discs

4 and 5 and the intermediate component 8, is prevented from rotating by the cam 9, the pin 16 locks the running wheel 1 when a vertical dipping of the running wheel body 13 into a ratchet notch 17 occurs, and thus locks the running wheel 1 in respect of its running mobility. If in accordance with FIG. 2 and FIG. 10 the tracking wheel 3 is again raised, then the pin 16 leaves the ratchet notch 17 of the running wheel body 18 and thus frees the running wheel 1 again, so that it can now again travel freely over a level floor.

The swivel castors illustrated have additionally furthermore a vertically lowerable locking member 20, which is likewise controlled by the conjointly rotating tracking wheel 33 and serves for locking the castor fork 1 1 in respect of its swivelling mobility. When travelling over a level floor the vertically lowerable locking member 20 is and remains continuously raised by the conjointly rotating tracking wheel 3. When the conjointly rotating tracking wheel 3 dips into a groove 15 of the conveyor belt 14, the vertically movable locking member follows the vertical movement of the conjointly rotating tracking wheel v3 and sinks with the tracking wheel 3 into its locking position, causing the locking of the castor fork 11. In the case of the swivel castors of FIGS. 5 to 8 and FIGS. 13 to 20, the vertically movable locking member 20 is controlled from one of the

bearing discs

4 and 5 of the conjointly rotating tracking wheel 3 and is raised, for which purpose in these examples the bearing disc 5 of the conjointly rotating tracking wheel 3 has an upper extension 19 which controls and raises the locking member 20. In the case of the swivel castors of FIGS. 1 to 4 and FIGS. 9 to 12 the vertically movable locking member 20 lies on the wheel periphery 13 of the conjointly rotating tracking wheel 3 and is controlled and raised by the wheel periphery l3.

In the case of the swivel castors of FIGS. 1 to 12 the locking member 20 in each case is formed by a vertically movable locking pawl 21, which when the conjointly rotating tracking wheel 3 sinks down, engages in its catch or locking position. The locking pawl 21 is in each case supported in the hollow 28 of the castor fork 1 1 and when a sinking of the conjointly rotating tracking wheel 3 takes place can engage that is, catch, in fixed teeth 29 on the swivel castor back-set or rear bearing 30. In the case of the swivel castors shown in FIGS. 1 to 8 it is a question in each case of a locking pawl 22, which is supported at one end on a spindle or axle 31 in the fork hollow 28. In the case of the swivel castor of FIGS. 7 to 10 the locking pawl takes the form of a two-armed lever 23, which is likewise supported on an axle or spindle 31 in the fork hollow 28. In all three cases the

pawls

21,22 or 23 are located by a spring 32, which is partly a leaf spring and partly a spring clip. The spring 32 presses the

pawls

21,22 or 23 in each case downwards. When travelling over a level floor the

pawls

21,22 or 23 are lifted by the conjointly rotating tracking wheel 3 against the pressure of the spring 32. In the case of the swivel castors of FIGS. 1 to 4 and FIGS. 9 to 12 the

pawls

22 and 23 are applied by a projection 33, consisting of noise-reducing elastic material, on the wheel periphery 13 of the conjointly rotating tracking wheel 3 and can thus follow the sinking movement of the tracking wheel 3. In the case of the swivel castors of FIGS. to 8 the pawl 22 is applied on the upper extension 19 of the bearing disc 5 of the conjointly rotating tracking wheel 3, as a result of which the said pawl 22 can follow the sinking movement of the tracking wheel 3. instead of this arrangement however it is also possible for the pawl 22 to be articulately connected to the upper extension 19 of the bearing disc 5 of the conjointly rotating tracking wheel 3, then being compelled to follow the vertical movements of the tracking wheel 3.

in the case of the swivel castor shown in FIGS. 13 to 16 the swivel castor back-set bearing 30 has a fixed cap 34, in which a small locking pawl 24 is supported in such a way as to be vertically movable. The pawl 24 can engage in an incision 35 of the castor fork 11, thus locking the castor fork 11 in such a way as to prevent it from swivelling. The pawl 24 is controlled by the bearing disc 5 of the conjointly rotating tracking wheel 3 by means of an upper extension 19. When travelling over a level floor the tracking wheel 3 lifts the pawl 24 until the upper extension 19 of the bearing disc 5 completely closes the locking incision 35 of the swivel castor fork 11. By this the locking pawl 24 is again released so that then the castor fork is again free to move swivellingly. if when travelling over a ribbed conveyor belt 14 the tracking wheel 3 clips into one of its grooves 15 (FIGS. 15 and 16). then the bearing disc 5 simultaneously sinks downwards and its upper extension 19 frees the fork incision 35 so as to permit catch engagement of the locking pawl 24, so that then the castor fork 11 is braked.

in the case of the swivel castor of FIGS. 17 to 20 a catch pin 26 is supported in the swivel castor back-set bearing 30, which pin is vertically movable and is accured against rotation. A locking disc is provided at the lower end of the catch pin 26 in the fork hollow 28. The vertically displaceablc catch pin 26 is applied under the influence of its own weight by its lower end 27 on a bracket 36, which is provided on an upper extension 19 of the bearing disc 5 of the conjointly rotating tracking wheel 3. Because of this arrangement the vertically displaceable catch pin 26 can then follow the vertical movements ofthe tracking wheel 3. When travelling over a level floor the catch pin 26 is held by its lower locking disc 25 continuously in its top dead centre position. if the swivel castor arrives on a ribbed conveyor belt 14, then the tracking wheel 3 can dip into one of the grooves 15 of the conveyor belt 14. When this sinking of the conjointly rotating tracking wheel 3 takes place, its bearing disc 5 also sinks, which causes the catch pin 26 applied on the bracket 36 to sink conjointly also, under its own weight. This causes the lower locking disc 25 of the catch pin 26 to engage in ratchet teeth 37 which are fixed in the hollow 28 of the castor fork 11 to this. When the tracking wheel 3 rises, the bracket 36 also presses the catch pin 26 up again, because of which its locking disc 25 leaves the ratchet teeth 37 of the fork 11, so that then the castor fork 11 is freely movable again and the swivel castor can roll in any direction desired over the level floor.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

l. A swivel castor for mobile appliances which are entrained or conveyed on grooved conveyor belts, particularly for shopping trolleys in self-service stores, said castor comprising a swivellable castor fork, an axle held by said fork a running wheel mounted on said axle, a vertically movable tracking wheel mounted freely tumably on said axle parallel to the running wheel to follow said running wheel in continuous contact with the floor, a locking mechanism and means operableon movement of said tracking wheel into a groove of said conveyor belt to cause said locking mechanism to lock the running wheel against running mobility, characterised in that the castor further comprises a vertically movable member controlled by said tracking wheel for also locking said castor fork against swivelling mobility, said locking member being arranged to remain continuously raised during travel of the castor on a level floor, and to follow the movement of the tracking wheel when entering a groove in the conveyor belt to sink into its locking position and thus effect locking of the castor fork.

2. A swivel castor as claimed in claim 1, wherein the vertically movable locking member is controlled and riased by a bearing disc of the tracking wheel.

3. A swivel castor as claimed in claim 2, wherein the bearing disc of the tracking wheel has an upper extension which controls and raises the locking member.

4. A swivel castor as claimed in claim 1, wherein the vertically movable locking member is applied on the wheel periphery of the tracking wheel and is controlled and raised by the said wheel periphery.

5. A swivel castor as claimed in claim 1, wherein the locking member is a pawl which engages in its locking position when the tracking wheel sinks relatively to the running wheel.

6. A swivel castor as claimed in claim 5, wherein the pawl is supported in the hollow of the castor fork, and when the tracking wheel sinks down, said pawl engages fixed teeth on the holding device of the castor back-set or rear bearing.

7. A swivel castor as claimed in claim 6, wherein the pawl is supported by one of its ends on an axis or spindle in the fork hollow.

8. A swivel caster as claimed in claim 6, wherein the pawl is a two-armed level which is supported on an axle or spindle in the fork hollow.

9. A swivel castor as claimed in claim 8 wherein the pawl is spring-loaded by a spring which presses the pawl downwards, and the said pawl is raised against the spring pressure by the tracking wheel.

10. A swivel castor as claimed in claim 3 wherein the pawl is applied on the wheel periphery of the tracking wheel and can thus follow its sinking movement.

11. A swivel castor as claimed in claim 10, wherein the pawl is applied by a projection of noise-reducing pawl is supported on the fixed holding device of the castor back-set or rear bearing and can catch-engage in an incision or groove or the like in the castor fork.

15. A swivel castor as claimed in claim 14 wherein an upper extension of the bearing disc of the tracking wheel during travel over a level floor closes the locking with it and can thereby catch-engage by means of its lower locking disc in ratchet teeth in the hollow of the castor fork.

17. A swivel castor as claimed in claim 16, wherein the vertically displaceable catch pin is applied by' its lower end on a bracket of an upper extension of a bearing disc of the tracking wheel and can thus follow its vertical movements.

i 4 W 4 t

Claims

1. A swivel castor for mobile appliances which are entrained or conveyed on grooved conveyor belts, particularly for shopping trolleys in self-service stores, said castor comprising a swivellable castor fork, an axle held by said fork a running wheel mounted on said axle, a vertically movable tracking wheel mounted freely turnably on said axle parallel to the running wheel to follow said running wheel in continuous contact with the floor, a locking mechanism and means operable on movement of said tracking wheel into a groove of said conveyor belt to cause said locking mechanism to lock the running wheel against running mobility, characterised in that the castor further comprises a vertically movable member controlled by said tracking wheel for also locking said castor fork against swivelling mobility, said locking member being arranged to remain continuously raised during travel of the castor on a level floor, and to follow the movement of the tracking wheel when entering a groove in the conveyor belt to sink into its locking position and thus effect locking of the castor fork.

7. A swivel castor as claimed in claim 6, wherein the pawl is supported by one of its ends on an axle or spindle in the fork hollow.

8. A swivel castor as claimed in cLaim 6, wherein the pawl is a two-armed level which is supported on an axle or spindle in the fork hollow.

9. A swivel castor as claimed in claim 5 wherein the pawl is spring-loaded by a spring which presses the pawl downwards, and the said pawl is raised against the spring pressure by the tracking wheel.

10. A swivel castor as claimed in claim 5 wherein the pawl is applied on the wheel periphery of the tracking wheel and can thus follow its sinking movement.

11. A swivel castor as claimed in claim 10, wherein the pawl is applied by a projection of noise-reducing elastic material on the wheel periphery of the tracking wheel.

12. A swivel castor as claimed in claim 5, wherein the pawl is applied on an upper extension of the bearing disc of the tracking wheel and can thus follow its sinking movement.

13. A swivel castor as claimed in claim 12, wherein the pawl is articulately connected with the upper extension of the bearing disc of the tracking wheel.

14. A swivel castor as claimed in claim 5, wherein the pawl is supported on the fixed holding device of the castor back-set or rear bearing and can catch-engage in an incision or groove or the like in the castor fork.

15. A swivel castor as claimed in claim 14 wherein an upper extension of the bearing disc of the tracking wheel during travel over a level floor closes the locking incision or notch of the swivel castor fork and when the tracking wheel sinks down, frees the fork incision or notch for the catch engagement of the pawl.

16. A swivel castor as claimed in claim 1, wherein there is supported in the swivel castor back-set or rear bearing a vertically displaceable catch pin secured against twisting or rotation with a lower locking disc which during travel over a level floor is held by the tracking wheel continuously in its top dead centre and which when the tracking wheel sinks down sinks down with it and can thereby catch-engage by means of its lower locking disc in ratchet teeth in the hollow of the castor fork.

17. A swivel castor as claimed in claim 16, wherein the vertically displaceable catch pin is applied by its lower end on a bracket of an upper extension of a bearing disc of the tracking wheel and can thus follow its vertical movements.