GB2174295A - Castor wheel assembly - Google Patents

Abstract

A castor wheel assembly having a wheel fork which mounts the runner wheel and the back of which is pivotally supported by thrust bearings 19, 20 which are held together axially by means of a mounting journal 18 which projects upwardly through the thrust bearings, wherein the fixing arrangement has a threaded journal 21 which is coaxially connected to the mounting journal 18 and which engages through two clamp members 23, 24 and which holds them together non-rotatably with a nut 25 tightened thereon, wherein the clamp members 23, 24 have lateral arcuate lugs 26, 27 engaging two, in particular adjacent, horizontally extending grid bars 28 of the cart at mutually remote sides thereof. <IMAGE>

Description

SPECIFICATION Runner wheel assembly The invention relates to a castor wheel assembly comprising awheelforkwhich mountsthewheel and the back of the fork is supported pivotally by a thrust bearing which is held together axially by means of a journal which extends upwardly beyond the thrust bearing and which has afixing arrangement by which the runnerwheel assembly can be fixed to a grid-like frame structure of a truck ortrolley.

In a known castorwheel assemblyofthe kind referred to above, the fixing arrangement comprises a plate-like extension portion of the journal, the extension portion projecting upinthecentreofthethrust bearing and engaging between two vertically extending grid bars oftheframe structure of a transportcart ortrolley. Arranged between two horizontally extending grid bars oftheframe structure ofthecarortrolley is a co-operating plate which fits over the vertical grid bars ofthe frame structure.Both the plate-like extension portion ofthe mounting journal and also the co-operating plate are clamped together by way of a screw memberwhich passes thereth rough, so thatthe journal and therewith the wheel assembly is fixed to thecartortrolley. Howeverthatclamping action is possible only because there is a small spacing between the extension portion of the journal and the co-operating plate. However that spacing is predetermined by production ofthe grid-likeframe structure of each cartortrolley, and is relatively small.Now, greatly tightening the screw nut relative to the threaded journal can result in deformation ofthe extension portion ofthe mounting journal orthe co-operating plate so that the extension portion ofthe journal and the co-operating plate come to bear against each other. There is then no longer any possibility offurther clamping the components together, in which respect, particularly when the carts ortrolleys are in use over a long period oftime, the arrangement can result in chatter or rattling noises at the fixed location, the constant changes in loading in particular contributing to producing such noises.

In a further known runner wheel assembly, the fixing arrangement has a clamping loop member which is connected to the mounting journal and which istheform of a half-shell memberembracing avertical grid bar ofthe cart oftrolley, with two clamping flanges which engage in a closing condition between two spaced-apart horizontally disposed grid bars and which can be braced relative to each other. With that fixing arrangement howeverthe clamping member must be adapted to the diameter of the vertical grid bar and the clamping flanges which can be braced relative to each other must be adapted in respect of width tothespacing ofthe horizontal grid bars in order to avoid rattling and wobbling, in spite ofthe comparativelywidetolerances.

According to the present invention there is provided a castor wheel assembly comprising a fork which mounts the wheel and the back of which is pivotally supported by thrust bearings which are held together axially by means of a journal which extends upwardly beyond the thrust bearings and which has a fixing arrangement by which the wheel assembly can be fixed to a grid-likeframe structure of a truck ortrolley, said fixing arrangement comprising a threaded journal which is coaxially cpnnected to the journal and which extends through two clamp members and which holds them non-rotatablytogetherbya nut provided thereon, said clamp members having lateral arcuate lugswhich in usegriptwo horizontally extending grid bars of the truck ortrolley at mutually opposite portions.

The two clamp members can be easilyfitted with the openings therein onto thethreadedjournal which is connected to the mounting journal is coaxial relationship, and can be non-rotatably clamped together by means ofthe nut, the lateral arcuate lugs embracing two, in particular adjacent, horizontally extending grid bars ofthe cart ortrolley, at sides which are remote from each other. That providesthatthe runner wheel assembly is fixed to the cartortrolley in a rattle-free manner and in a reliable fashion.

The two clamp members may be provided at the faces thereof which are directed towards each other, on the one hand with a projection which projects out ofthe face and on the other hand with a recess in the other face which positively receives the projection. In that way the two clamp members are non-rotatably connected together in a simple fashion in the clamping position so that tipping loadings orthe like which occuratthe runnerwheel assembly are always transmitted simultaneously by way of both clamp members to the two adjacent grid bars of the cart or trolley.

The projection which projects from the face of the one clamp member may be formed by a rib which extends overthe entire width ofthe clamp members and which extends parallel to the horizontally extending grid bars ofthe cart, and the recess in the other clamp face is formed by a groove which positively accommodates the rib. Thus, engagement ofthe rib intothe groove provides in asimplemannerthatthe two clamp members are arranged non-rotatably relative to each otherovera substantial area so that rotary movements ofthe one clamp member are transmitted to the second clamp member, over a large surface area.

The two clamp members may be formed of plastics material and may be of a substantially square cross-section, while the sides, which are remote from the arcuate lugs are rounded off in concentric rela tionshipto the threaded journal. In thatway, in spite of being of small dimensions, the clamp members have the necessary stability for transmission ofthe forces acting on the runnerwheel assembly.

The lateral arcuate lugs may each extend over the entire width ofthe respective clamp members and may embrace the grid bars ofthe cart ortrolley at the sides which are remote from each other, approximate ly overan angle of 180 . Thus,the clamp members bear against the grid bars overthe entire width ofthe clamp members so that rotational moments which occur at the runner wheel assemblies are carried by the grid bars, over a wide area. In that arrangement the arcuate lugs embrace the grid bars at the sides which are remotefrom each other, approximately over an angle of 1 80" so that there is no fear of the clamp members slipping offthe grid bars ofthe cart.

The inside diameterofthe arcuate lugs may correspond to the outside diameter ofthe grid bars.

That provides that the grid bars are embraced in a form-locking or positive fashion by the lateral arcuate lugs on the clamp members.

The two clamp members may each comprise a flat bar which is bent substantially into a U-shaped configuration, with limb portions extending in parallel relationship, with the threaded journal extending through both limb portions ofthe respective substantially U-shaped metal member of each clamp member. That arrangement makes it possible for manufactureto be particularly inexpensive astheflat bars only have to be bent into a U-shaped configuration and apeturesthen have to be formed in the two limb portions ofthe U-shaped member. Another advantage in that connection isthatthe U-shaped members can be resiliently compressed when the two clamp members aretightenedtogether.

The arcuate lugs,forengaging the horizontally extending grid bars ofthe cart, maybeformedatthe mutually remote limb portions ofthetwo U-shaped metal members which form the clamp members.

Thus, the arcuate lugs may advantageously be formed by extensions of the mutually remote limb portions of the U-shaped metal members.

Thearcuatelugswhichareformedonthemutually remote limb portions ofthetwo U-shaped metal members which form the clamp members may embracethegrid bars ofthecart,atthe mutually remote sides thereof, approximately over an angle of 90 , with the grid bars coming to bear against the threaded journal. Althoughthearcuate lugs only embracethe grid bars ofthe cart over an angle of about 900, displacement ofthe grid bars in the longitudinal direction ofthe limb portions ofthe U-shaped metal members is prevented as the horizontal grid bars of the cart come to beat againstthe threaded journal.

Thethreaded journal may engage non-rotatably by means of a non-round enlargement portion into an opening enlargement portion in the clamp member which is towards the runnerwheel. In that way, the threaded journal is also connected non-rotatablyto the two clamp members in a simplefashion so that rotary movement of the threaded journal relative to the clamp members is reliably prevented.

The width ofthe clamp members may correspond to the inside width between two adjacent vertical grid bars ofthe cart. That arrangement provides in a simple fashion that lateral displacement ofthe clamp members on the horizontal grid bars of the cart is prevented by positive orform-locking means.

Two embodiments ofthe invention will now be described, by way of examples, with references to the accompanying drawings in which: Figure lisa partly broken-away side view of a castor wheel assemblywith the first embodiment of its fixing arrangement, Figure 2 is a view of part ofthe castor wheel assembly in section taken along the line il-ll indicated in Figure 1, Figure 3 is a plan view ofthe runner wheel assembly shown in Figure 1, Figure 4 is a partly broken-away side view of a castor wheel assemblywith the second embodiment of its fixing arrangement, Figure5 is a view ofpartofthe runnerwheel assembly shown in Figure 4, in section taken along the line V-V indicated in Figure 4, Figure 6 is a plan view of the castor wheel assembly shown in Figure 4, and Figure 7 is a view in section taken along the line VII-VII indicated in Figure 5.

In both embodiments, the castorwheel assembly comprises a wheel supportingfork 10 comprising fork limbs 11 and 12 in which is disposed a spindle 13 supporting a wheel 14. Thetwo limbs 11 and 12 ofthe fork 10 areconnected together byway of a back portion 15 which engages between an upper bearing shell 16 and a lower bearing shell 17. The bearing shells 16, 17 are connected together byway of a mounting journal 18 in such a way that two rings of balls 19 and 20 are arranged on the one hand between the back portion 1 5ofthefork 10 and the upper bearing shell 16 and on the other hand between the back portion 15 and the lower bearing shell 17.The journal 18 in that arrangement performs the function of a rivetwhich holds the two bearing shells 16 and 17 together in the axial direction non-rotatably relative to each other.

Fixedly connected to the head portion ofthe journal 18, which projects beyond the upper bearing shell, is a threaded journal 21 which extends through two clamp members 23 and 24 provided with openings22, and holds them together by means of a nut 25 tightened thereon. The two clamp members 23 and 24 have lateral arcuate lugs 26 and 27 formed thereon respectivelywhich embracetwoadjacenthorizontallyextending bars28ofthetransportcartortrolleyatthe sidesthereofwhich are remote from each other so that the castorwheel assembly is reliably fixed to two horizontally extending bars 28 ofthe cart ortrolley.

In the embodiment illustrated in Figures 1 to 3, the clampmembers23and24areformedfrom plastics material and are of a substantially square crosssection, with the sides remote from the arcuate lugs 26 and 27 being rounded off concentrically with respect tothethreaded journal 21.1nspite ofthe clamp members 23 and 24 being of small dimensions, that arrangement provides a high level of stability which is capable of carrying any loadings.

As can be seen in particularfrom Figure2,thetwo clamp members 23 and 24 bear against each other at their respective faces, in the clamping position. It will be appreciated that it is also possible for the faces of the two clamp members 23 and 24to be disposed ata smallspacingfrom each other in orderto permitthem subsequentlyto be tightened together. The upper clamp members 23 in that arrangement is provided with a rib-like projection which projects out ofthe face 29 and which is arranged parallel to the horizontally extending grid bars 28 ofthe cart ortroiley. The rib-like projection 30 engages positively into a corresponding groove 31 in the face 32 ofthe other clamp member 24 so thatthetwo clamp members 23 and 24are non-rotatably connected together and transmit all loadings uniformlyto the two grid bars 28 ofthe cart.

The lateral arcuate lugs 26 and 27 each extend over the entire width ofthe clamp members 23 and 24 and embrace the horizontally extending grid bars 28 ofthe cart at the sides which are remote from each other, overran angle of about 1800. The loadings which occur at tire wheel l4arethus carried by the grid bars 28 of the cart, oveTa iarge surface area, while the width of the clamp members 23 and 24 may also correspond to the inside width between two adjacent vertical grid bars 33 ofthe cart. The clamp members 23 and 24thus positively engage the horizontal grid bars 28 of the cart and engage positively between two adjacent vertical grid bars 33 ofthe cart.

The inside diameter ofthe arcuate lugs 26 and 27 corresponds to the outside diameter ofthe horizontal grid bars 28 ofthe cart, so that here too the arrangement ensures positive engagements.

In the embodiment illustrated in Figures 4to 7, the two clamp members 23 and 24 each comprise a respective flat bar 34 which is bent over into a substantially U-shaped configuration, with limb portions 35 and 36 which extend in parallel relationship.

In thatarrangementthethreaded journal 21 extends through respective openings 22 in the two limb portions35 and 36 ofthe substantially U-shaped metal member 34 of each clamp member 23 and 24. The two clamp members 23 and 24 can thus be formed in a simple mannerfrom a flat bar portion 34 by bending overthe limb portions 35 and 36. In that connection the two U-shaped metal members 34 may be resiliently compressed when the nut25 istightened on the threaded journal 21 in orderto adaptthem to the spacing ofthe horizontal grid bars 28, when the two U-shaped metal members 34 come to bear against each other.

The arcuate lugs 26, for engaging the horizontal extending grid bars 28 ofthe cart, are formed on the mutually remote limb portion 36 ofthetwo U-shaped metal members 34 which form the clamp members 23 and 24. The arcuate lugs 26 formed on the respective clamp memberembracethe grid bars 28 ofthe cart at the sides which are remote from each other, over an angle ofapproximately 900, with the grid bars 28 coming to bear against the threaded journal 21.There is therefore no fear ofthe clamp members 23 and 24 slipping in the longitudinal direction ofthe limb portions 35 and 36 on the bars 28.

At its limb portion 35, the lower clamp member 24 has a projection 37 which projects out of the face of the clamp member24andwhich is fixed in position by welding. However the projection 37 may also be formed in a simple manner by a bent-overtongue portion, while the free space formed bythetongue portion which is cut out of the limb portion 35 at the same time forms the opening 22 in the limb portion 35 ofthe U-shaped metal member34. The projection 37 engages positively into a corresponding opening 38 in the limb portion 35 of the clamp member 23 so that the two clamp members 23 and 24 are non-rotatably fitted onthethreadecijournal 21.

The threaded journal 21 has a non-round enlargement portion 39 which engages non-rotatably into a corresponding opening enlargement portion 40 in the clamp member 24 which is towards the runnerwheel 14. In that way, the threaded journal 21 is non- rotatably connected to the two clamp members 23 and 24 in a simple mannerso thatthere is no possibility of the threaded journal 21 rotating within the two clamp halves 23 and 24.

In the embodiment shown in Figures 4to 7, the width ofthe clamp members 23 and 24 also corresponds to the inside width between two adjacent vertical grid bars 33 ofthe cart. In this embodiment also therefore lateral displacement ofthe clamp members 23 and 24 on the horizontal grid bars 28 of the cart is prevented by positive or form-locking engagement.

Claims (12)

1. Acastorwheel assembly comprising afork which mounts the wheel and the back of which is pivotallysupported by thrust bearings which are held together axially by means of a journal which extends upwardly beyond the thrust bearings and which has a fixing arrangement bywhich thewheel assembly can be fixed to a grid-like frame structure of a truck or trolley, said fixing arrangement comprising a threaded journal which is coaxially connected to the journal and which extends through two clamp members and which holds them non-rotatably together by a nut provided thereon, said clamp members having lateral arcuate lugs which in use grip two horizontally extending grid bars of the truck ortrolley at mutually opposite portions.

2. Acastorwheel assembly as claimed in claim 1, in which the two clamp members are provided at faces which are directed towards each other, on the one hand with a projection which projects out of one face and on the other hand with a recess in the otherface which positively receives the projection.

3. Acastorwheel assembly as claimed in claim 2, in which the projection which projects out of the one face is formed by a rib which extends over the entire width oftheclamp membersandwhich extends parallel to the horizontal extending grid barsofthe car, and the recess in the other clamp face is formed by a groove which positively accommodates the rib.

4. Acastorwheel assembly as claimed in any one ofthe claims 1 to 3, in which the clamp members are formed of plastics material and are of a substantially square cross-section, the sides which are remote from the arcuate lugs being rounded off concentrically with respecttothethreadedjournal.

5. Acastorwheel assembly as claimed in any one ofthe claims 1 to 4, in which the lateral arcuate lugs each extend overthe entire width ofthe respective clamp members and embrace the grid bars of the cart at the mutually remote sides approximately over an angle of 1800.

6. Acastorwheel assembly as claimed in any one ofthe claims 1 to 5, in which the inside diameter ofthe arcuate lugs corresponds to the outside diameter of the grid bars.

7. Acastorwheel assembly as claimed in any one of claims 1 to 6, in which the two clamp members each comprise a flat barwhich is bent substantially in a U-shaped configuration, with limb portions extending in parallel relationship, wherein said threaded journal extends th rough both limb portions ofthe respective substantially U-shaped metal member of each clamp member.

8. A castor wheel assembly as claimed in claim 7, in which the arcuate lugsforengaging the horizontally extending grid bars are formed at the mutually remote limb portionsofthetwo U-shaped metal loop members that form the clamp members.

9. A castor wheel assembly as claimed in claim 7 orclaim 8, in which the arcuate lugs which are formed at the mutually remote limb portions ofthe two U-shaped metal members forming the clamp members embracethe grid bars at the mutually remote sides approximately over an angle of 90% wherein the grid barscometo lie againstthethreadedjournal.

10. A castor wh eel assembly as claimed in any one of claims 1 to 9, in which the threaded journal engages non-rotatably by means of a non-round enlargement portion into an opening enlargement portion in the clamp memberwhich is towards the wheel.

11. Acastorwheel assembly as claimed in any one of claims 1 to 10, in which thewidth oftheclamp members corresponds to the inside width between two adjacent perpendicular grid bars of the cart.

12. A castor wheel assembly substantially as hereinbefore described with reference to and as illustrated infigures 1 to 3 orfigures 4to 7 ofthe accompanying drawings.