GB2218053A

GB2218053A - Trolley wheel arrangement

Info

Publication number: GB2218053A
Application number: GB8810631A
Authority: GB
Inventors: Gerald Eric Lloyd
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-05-05
Filing date: 1988-05-05
Publication date: 1989-11-08
Also published as: GB8810631D0

Abstract

A pair of wheels 34, 35 are mounted intermediate the front and rear wheels 17, 18, 25, 26 for ground engaging rotation about a horizontal axis 36 disposed permanently at right angles to the longitudinal axis P. Typically the front pair or the rear pair of wheels or both the front and the rear pair of wheels are pivotably attached to the trolley so as to provide a trailing castor action to facilitate steering of the trolley and the trailing arms 21, 22, 29, 30 are preferably spring loaded. Preferably the intermediate and the front and rear wheels are so disposed on the chassis that with the trolley freely displacable on a horizontal surlace the intermediate pair of wheels are permanently in contact with the surface together with either the front pair or the rear pair of wheels. <IMAGE>

Description

TROLLEY This invention relates to a trolley. It is particularly concerned with a trolley of the general type extensively provided and used in supermarkets, airport termini and other locations for temporary use, and propulsion, by pedestrians wishing to transfer objects such as purchases, luggage or equipment from one location to another. A trolley of this general type takes the form of a raised basket permanently secured to a chassis which is supported by four wheels or castors. The basket is provided with a handle whereby the trolley can be propelled by the user.

The basket is disposed at a height such that objects can be readily placed into and removed from it without the need for excessive vertical movement by a user of average height.

However this means that the centre of gravity of a loaded trolley is comparatively high.

The wheels, like those of a motor car, are generally disposed with two front and two rear wheels. The disposition can be in a rectangular pattern or with the normally leading pair mounted closer together than the rear pair. At least the front wheels are generally mounted on offset trailing pivots so that in of pushing the trolley the trailing pivots cause their associated wheels to swing into a trailing position relative to the direction of movement.

A loaded trolley can be difficult to push across a sloping floor (that is to say when following a path when one side of the trolley is lower than the other). On such a path a high centre of gravity acts to to cause the trolley to twist about an axis perpendicular to the slope so that the trolley lies at an angle to the direction of travel. A general trolley of the type referred to need not necessarily be well maintained and if at least one of the wheels or castors does not rotate readily either about its horizontal axes of symmetry or, in the case of at least the leading wheels when pushed, about a steering axis then the ready propulsion of such a trolley along a particular path becomes problematic even for an experienced user.

According to the present invention there is provided a trolley having a pair of front and a pair of rear wheels disposed symmetrically on a chassis relative to a longitudinal axis thereof characterised in that the chassis is also supported by a pair of wheels mounted intermediate the front and rear wheels for ground engaging rotation about a horizontal axis of symmetry which axis is disposed permanently at right angles to the longitudinal axis.

An exemplary embodiment of the invention will now be described with reference to the accompanying drawing of a supermarket trolley of which: Figure 1 is a side view; Figure 2 is a perspective view of a part of Figure 1, and Figure 3 is a plan view of components shown in Figure 2.

Figure 1 shows a trolley 10 made up of a basket B permanently secured by support S to a wheeled chassis member 11. The basket B is provided with a horizontal bar handle H.

Figure 2 and 3 show chassis member 11 which has a front transverse section 12 and side arms 13, 14 which are splayed outwardly so as to lie symmetrically on either side of axis P which represents the normal path of travel (in direction F) of the trolley 10. Rear end spacing 15 of side arms 13 is greater than front end spacing 16.

Front wheels 17, 18 are mounted for rotation about, respectively, individual horizontal axes 19, 20 on, respectively, trailing arms 21, 22. The trailing arms 21, 22 are adapted for rotation about, respectively, vertical axes, 23, 24.

Rear wheels 25, 26 are mounted for rotation about, respectively, individual horizontal axes 27, 28 on, respectively, trailing arms 29, 30. The trailing arms 29, 30 are adapted for rotation about, respectively, vertical axes, 31, 32.

Figure 3 shows tilte position in plan view of handle H. The handle H is positioned about 36 inches above the normal floor level.

Intermediate wheels 34, 35 are mounted for rotation about common axis 36 on, respectively, fixed arms 37, 38, which are secured to the chassis member 11 so maintaining axis 36 at right angles to axis P. The intermediate wheels 34, 35 are disposed on the chassis 11 to lie approximately midway between the front and rear wheels at a point approximately beneath the centre of gravity of the trolley which, when uniformly loaded, is taken to lie vertically above area A.

The trailing arms 21, 22 and 29, 30 (unlike fixed arms 37, 38) incorporate springs so that with a loaded trolley the front wheels 17, 18 and rear wheels 25, 26 tend to retract vertically in contrast to the rigid mounting of intermediate wheels 34, 35.

With the trolley loaded and pushed in the direction of arrow F the intermediate wheels 34, 35 between them take a major proportion (that is to say over one third) of the overall load.

To turn the trolley to the left (as seen in Figure 3) the handle H while continuing to be pushed is drawn appropriately to the right as shown by arrow 40 so causing a moment of force to act made up of the force applied and the distance between the handle and a point M mid-way between the intermediate wheels 34, 35 on axis 36. Given the steering action referred to the trailing arms 21, 22, 29 and 30 take up positions as shown so that their associated wheels follow the required track while providing support for the trolley. The fixed tracking direction of intermediate wheels 34, 35 results in any tendency on the part of trolley 10, typically when heavily loaded, to drift in a direction transverse the axis P as can arise, for example, due to passage over an inclined floor or with one or more non-compliant wheel alignment among the front or rear wheels.

While the specific embodiment describes a supermarket trolley it will be readily apparent that the invention is applicable to a wide range of trolleys intended for different types of load.

Thus for particular types of load the proportions of the trolley can be adapted to optimise the ability of the trolley to support the load in the most effective manner which enables the intermediate wheels 34, 35 to function in the manner previously described. This while a supermarket trolley is concerned with carrying a sometimes substantial load of small and medium size goods a trolley for carrying sheets or lengths of timber or wood or sheets or bars of metal or plastic material or pipework involves the provision of stable transport for unwieldy material. A trolley for this purpose is readily constructed according to the invention.

A trolley according to the invention can incorporate features to enable a number of such trolleys to be pushed together for nesting so providing for a reduced parking length for the nested trolleys. - Apart from the tapered view in plan the rear end of each trolley is adapted to receive the front end of another by having a folding basket section which is raised out of the way as the front of the rear trolley is pushed into the rear of the front trolley.

Claims

1A trolley having a pair of front and a pair of rear wheels disposed symmetrically on a chassis relative to a longitudinal axis thereof characterised in that the chassis is also supported by a pair of intermediate wheels mounted intermediate the front and rear wheels for ground engaging rotation about a horizontal axis of symmetry which axis is disposed permanently at right angles to the longitudinal axis.

2 A trolley as claimed in Claim 1 wherein the front pair or the rear pair of wheels or both the front and the rear pair of wheels are pivotably attached to the trolley so as to provide for said pairs of wheels to adapt a trailing castor action to facilitate steering of the trolley.

3 A trolley as claimed in any preceding claim wherein the the intermediate and the front and rear wheels are so disposed on the chassis that with the trolley freely displacable on a horizontal surface the intermediate pair of wheels are permanently in contact with the surface together with either the front pair or the rear pair of wheels and the major proportion of the total weight of the trolley tends to be carried by the pair of intermediate wheels.

4 A trolley as claimed in any preceding claim wherein the front pair or the rear pair of wheels or both the front and the rear pair of wheels are mounted for substantially vertical movement relative to the chassis, said vertical movement being constrained by resilient means, the intermediate pair of wheels are fixed against any substantially vertical movement relative to the chassis.

5 A trolley as claimed in any preceding claim wherein the distance between the wheels making up the front pair is different from the distance between the wheels making up the rear pair.

6 A trolley as claimed in any preceding claim wherein the chassis supports a load carrying unit such as a basket wherein the basket has a form, and is disposed relative to the chassis, such that the centre of gravity of the basket empty or when filled with objects of similar density lies substantially vertically above the horizontal axis of symmetry of the intermediate wheel pair.

7 A trolley as hereinbefore described with reference to, and as illustrated in, the accompanying drawing.

8 A trolley as claimed in any preceding claim being adapted for storage as one of a plurality of such trolleys by having a first and second nesting sections, the first section being configured to nest within a second section of a similar trolley, the second section being configured to receive the first section of a similar trolley; the resultant stacked plurality having an overall length which is less than the sum of the overall lengths of the same number of unstacked trolleys.

9 A trolley as claimed in any preceding claim adapted for carrying articles having a length substantially greater than that of the trolley such as longitudinal sheets, bars or tubes.