IMPROVEMENTS IN OR RELATING TO CASTOR WHEELS

Abstract: A castor wheel arrangement comprises a roll (7) turnable about a horizontal first axis (H1), a bracket (8) mounting the roll (7) for turning about the axis (H1) and turnable about a second axis (P) substantially perpendicular to the first axis (H1), a hinge lower leaf (10) or a rocking member mounting the bracket (8) for turning about the second axis (P) and turnable about a horizontal third axis (H2) substantially perpendicular to the second axis (P), and a hinge upper leaf (13) or a supporting cap mounting the hinge lower leaf (10) or the rocking member, as the case may be, for turning about the third axis (H2) and fixed to a frame (1) of a trolley.

Description: IMPROVEMENTS IN OR RELATING TO CASTOR WHEELS This invention relates to a castor wheel. According to the present invention, there is provided a castor wheel arrangement comprising a roll turnable about a first axis, bracket means mounting said roll for turning about said axis and turnable about a second axis substantially perpendicular to said first axis, connecting means mounting said bracket means for turning about said second axis and turnable about a third axis substantially perpendicular to said second axis, and supporting means mounting said connecting means for turning about said third axis . Owing to the invention, it is possible to minimise unwanted sideways veering of the supporting means, whilst allowing such sideways movement when desired. The supporting means may take the form of a chassis of a trolley, for example a supermarket or airport trolley, where the castor wheel arrangement can constitute the or each front or rear wheel of the trolley. In order that the invention may be clearly understood and readily carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: - Figure 1 is a diagrammatic side elevation of a supermarket trolley, with the trolley being advanced in a forward direction, Figure 2 shows a detail of Figure 1, but partly in vertical section, Figure 3 shows a sectional plan view taken on the line III-III of Figure 2, Figure 4 is a view similar to Figure 2, but with the trolley being advanced in a rearward direction, Figure 5 is a view similar to Figure 2, but more fragmentary, of a modified version, and Figure 6 is a view similar to Figure 4, but more fragmentary, of the modified version. Referring to Figures 1 to 4 of the drawings, the trolley has a frame 1 upon which is mounted a front pair of ground castor wheels (only the left-hand wheel 2 of which is seen) and a rear pair of ground castor wheels (only the left-hand wheel 3 of which is seen) . Each castor wheel of the front pair consists of a roll 4, and a yoke-form bracket 5 mounting the roll 4 so that the roll is turnable about a horizontal axis and itself so mounted by a bearing 6 on the frame 1 that the bracket 5 and thus the roll 4 are turnable about a vertical axis. Each of the rear castor wheels comprises a roll 7, a yoke-form bracket 8 mounting the roll 7 so that the roll is turnable about a first horizontal axis HI, and a hinge 11 whereof a lower leaf 10 so mounts the bracket 8 by way of a bearing 9 that the bracket 8 and the roll 7 are turnable about an axis P perpendicular to the axis HI, but offset relative to it. The upper leaf 13 of the hinge 11 is so fixedly mounted by a nut-and-bolt device 14 on the frame 1 that the leaf 10 and thus the bracket 8 and the roll 7 are turnable about the axis H2 of the hinge pivot pin 12, which is horizontal and perpendicular to the axis P, but offset relative to it. A nut-and-bolt device 15 sandwiches the bearing 9 between the bracket 8 and the leaf 10. The hinge 11 has a very restricted degree of opening, limited by a stud 16 fixed to the leaf 10 and having a neck 17 extending through an aperture 18 in the upper leaf 13 and a head 19 above the aperture 18 but too large to pass downwardly through it. Figures 1 to 3 show the condition of each of the rear castor wheels when the trolley is being advanced in the forward direction F. In that condition, the hinge 11 is fully closed and the axis P is inclined downwardly and rearwardly, so that the wheel tends to remain in the vertical plane of the direction F, under the weight of the trolley and its contents. If the person pushing the trolley steers the trolley to the left or the right, the roll 7 is thereby urged about the axis P out of the plane of the direction F, but against the weight of the trolley and its contents, so that the rear of the frame 1 needs to be raised increasingly with increasing deviation from the direction F, to the extent that, if the person starts to pull the trolley in the rearward direction R, the axis P reaches the condition shown in Figure 4 in which the axis P is virtually vertical, in fact preferably inclined downwardly and very slightly forwardly, the extent of movement of the axis P about the axis H2 in a clockwise sense being limited by engagement of the head 19 with the flange 13. As illustrated in Figures 5 and 6, it is possible to make each rear castor wheel more compact by arranging for the horizontal axis H2 to intersect, or come close to intersecting, the axis P. The hinge 11 has been dispensed with and, instead, the pivot pin 12 is borne at its opposite ends in respective opposite sides of a supporting cap 20 fixed to the frame 1, whilst the pin 12 carries a rocking member 21 to which the bracket 8 is pivotally connected by way of the nut-and-bolt device 15 and the bearing 9. The member 21 has opposite arms 22 and 23 which, by respectively coming to abut against the rear and the front of the cap 20, limit respectively the anti-clockwise and clockwise turning of the member 21, and thus the items 7 to 9, about the axis H2. Particular advantages of the castor wheel arrangements described with reference to the drawings are that no rearward movement of the trolley is required before a turn to the left or to the right, that no fifth wheel is required, that existing castor wheels on existing trolleys can easily and cheaply be replaced with the present castor wheels, and that, following such replacement, the nesting of the trolleys is not affected.

Claims: CLAIMS 1. A castor wheel arrangement comprising a roll (7) turnable about a first axis (HI) , bracket means (8) mounting said roll (7) for turning about said axis (HI) and turnable about a second axis (P) substantially perpendicular to said first axis (HI), connecting means (10;21) mounting said bracket means (8) for turning about said second axis (P) and turnable about a third axis (H2) substantially perpendicular to said second axis (P) , and supporting means (1, 13, 14; 1, 20) mounting said connecting means (10; 21) for turning about said third axis (H2) . 2. A castor wheel arrangement according to claim 1, and further comprising limiting means (17-19) limiting the degree of turning of said connecting means (10;21) relative to said supporting means (1, 13, 14; 1, 20) . 3. A castor wheel arrangement according to claim 1 or 2, wherein said connecting means (10) is provided by a lower leaf (10) of a hinge (11) , said third axis (H2) is provided by a hinge pivot pin (12) of said hinge (11), and said supporting means (1,13,14) includes an upper leaf (13) of said hinge (11) . 4. A castor wheel arrangement according to claim 3 as appended to claim 2, wherein said limiting means (17-19) comprises a headed stud (16) which is attached to one of the upper and lower leaves (10,13) and whereof a neck (17) extends through an apperture (18) in the other of the leaves (10,13), and the head (19) of said stud (16) is too large to pass through said aperture (18) . 5. A castor wheel arrangement according to claim 1 or 2, wherein said third axis (H2) substantially intersects said second axis (P) . 6. A castor wheel arrangement according to claim 5, wherein said third axis (H2) is provided by pivot pin means (12) borne at respective opposite ends in respective opposite side walls of said supporting means (1,20) . 7. A castor wheel arrangement according to claim 5 or 6, wherein said connecting means (21) comprises a rocking member (21) having respective opposite arms (22,23) which come to abut against respective portions of said supporting means (1,20) to limit respectively the anti-clockwise and clockwise turning of said connecting means (21) . 8. A castor wheel arrangement according to any one of claims 5 to 7, wherein said supporting means (1,20) includes a cap (20) . 9. A castor wheel arrangement according to any preceding claim, wherein said supporting means (1, 13, 14; 1, 20) includes a frame (1) of a trolley and said roll (7) is a ground roll

Inventors: FIRTH CHARLES DAVID, FIRTH ROGER, FIRTH, CHARLES, DAVID, FIRTH, ROGER
Applicants: FIRTH CHARLES DAVID, FIRTH ROGER, R & D MARINE LTD, FIRTH, CHARLES, DAVID, FIRTH, ROGER, R & D MARINE LIMITED
Application year: 1998
Main classification: B60B33
IPC codes: B60B33