Wheeled Trolley

Abstract

This invention is concerned with a folding four wheeled frame for a pushchair which has two front and two rear upwardly extending supports each of which carries at its lower end a wheel. The supports are pivotally connected to an upwardly extending backbone, and also connected near their lower ends to the lower end of the backbone by means of separate pivotal links. The front supports are connected near their upper ends to a first mounting adjacent to the top of the backbone by means of separate pivotal links, and the upper ends of the rear supports are pivotally connected to a second mounting on the backbone adjacent to the first mounting. The arrangement of the supports, backbone and mountings is such that the two mountings can be moved relatively to one another along the backbone whereupon the pivotal links enable the four supports to swing between a closed position nearer to the backbone and an open position further away from the backbone.

Description

The invention is concerned with a folding four wheeled frame for a child's or doll's pushchair.

In accordance with the invention such a frame comprises two front and two rear upwardly extending supports each of which carries at its lower end a wheel and which are pivotally connected to an upwardly extending backbone, each of the supports being connected adjacent to their lower ends to the lower end of the backbone by means of separate pivotal links, each of the front supports being connected adjacent to their upper ends to a fist mounting adjacent to the top of the backbone by means of separate pivotal links, and the upper ends of the rear supports being pivotally connected to a second mounting on the backbone adjacent to the first mounting, the arrangement being such that the two mountings can be moved relatively to one another along the backbone whereupon the pivotal links enable the four supports to swing between a closed position nearer to the backbone and an open position further away from the backbone.

With this construction we find that the wheel base of the frame can be made long enough and wide enough for good stability when the frame is open but when the frame is closed it contracts into a remarkably small overall volume.

Preferably the first mounting is fixed to the backbone and the upper ends of the rear supports are pivotally connected directly to the second mounting which is slidable to and fro along the backbone above the first mounting. In this way, when the frame collapses, the six pivotal links swing upwards about their pivotal connections to the backbone to bring the four supports close to the backbone and to shorten the overall length of the frame.

In order to provide a reaction to ensure the pivotal links fold in the right direction upon relative movement between the first and second mountings, a further pivotal link may be provided between each of those interconnecting the upper ends of the front supports and the first mounting, with the second mounting.

The relative movement between the two mountings may be provided by grasping the two mountings in the two hands and moving them together or apart but preferably a handle is provided which is pivoted to one of the mountings and is connected to the other mounting through a pivotal link so that by swinging the handle relatively to the backbone the two mountings are drawn together or forced apart. This movement could also be achieved by the use of a pinion and rack. The trolley will normally be provided with a pushing handle and this may be an integral extension of the upper end of the backbone. Alternatively it may provide the lever handle which is used for urging the two mountings together or apart and this is particularly suitable since it provides a good leverage for opening and closing the frame. However, if the pushing handle is pivoted relatively to the backbone it will be necessary in the open position to fix the pushing handle relatively to the backbone and this may be achieved by a simple swing catch. When the frame is closed the pushing handle may then fold downwards alongside the backbone, thus further shortening the overall length of the frame.

In order to limit the opening movement and strengthen the frame when open, it may be necessary to provide folding pivotal connection directly between the lower ends of the front supports. The folding link which is prevented from passing through its central position, may have its centre point attached to the lower end of the backbone by means of a strap which is tensioned on opening and which thus adds to the rigidity of the frame.

The lower ends of the rear supports may also require additional constraint and for this purpose the backbone may be made L-shaped with its lower and extending forwards, the four pivotal links from adjacent to the lower ends of the four supports being pivotally connected to a third mounting adjacent to the front end of the forwardly extending portion of the backbone. The lower ends of the rear supports may then be connected by means of pivotal links to a fourth mounting on the backbone just above the bend in the `L` of the backbone. Because of the geometry of the construction these pivotal links are preferably attached to the fourth mounting through a universal joint. A particularly suitable form of universal joint comprises two plates which extend across the backbone and are secured one to each side of it, the plates having at each end apertures or recesses in alignment with one another and trapping between them a ball end which is attached to the pivotal link. The L-shape of the backbone also gives clearance for the seat or other part to be carried by the frame.

All the four mountings may be made of a synthetic resin, the first, second and third mountings having central portions which embrace the backbone and wings to which the pivotal links and supports are pivotally connected.

The frame is preferably made of aluminium, the backbone and front and rear supports being tubular and the pivotal links being bars or pairs of interconnected bars.

One example of a pushchair having a frame which is constructed in accordance with the invention is illustrated in the accompanying drawings, in which:

FIG. 1 is a front perspective view of the chair erected;

FIG. 2 is a corresponding rear perspective view;

FIG. 3 is a side view showing the chair partially folded; and,

FIG. 4 is a rear view showing the chair completely folded.

The illustrated pushchair has a frame with tubular front supports 5, which are cranked to provide arm rests, and tubular rear supports 6, all provided at their lower ends with ground wheels 7 supported by double plate mountings 8.

The front and rear supports are all connected to an L-shaped backbone 9. At their upper ends the front supports 5 are each connected through a double bar pivotal link 10 to a corresponding projecting wing of a plastics mounting 11 which is fixed on the backbone 9, and each pivotal link 10 is connected through a further double bar pivotal link 12 to a corresponding wing on another plastics mounting 13 which is slidable along the backbone 9. At its upper end each of the rear supports 6 is pivoted directly to a corresponding wing of the mounting 13.

At its lower end each of the front supports 5 is connected to a double bar pivotal link 14 to a corresponding wing 15 of a plastics mounting 16 fixed on the horizontal arm of the L-shaped backbone 9. Each of the rear supports 6 is also connected to a corresponding wing of the mounting 16 by means of a double bar pivotal link 17. The lower end of each rear support 6 is additionally supported by means of a single bar pivotal link 18 one end of which is connected through a universal ball joint to a plastics mounting 19 on the backbone 9 just above the bend of the `L.` Each universal joint consists of a ball attached to the link 18 and sandwiched between two apertures in opposing plates of the mounting 19. The lower ends of the front supports are additionally supported and interconnected by means of a pivotal chain link 20 provided with foot rests 21 and connected at its centre through a flexible strap 22 to the forward end of the backbone 9.

A pushing handle 23 is pivoted at its lower end to the mounting 13 and through a double bar pivotal link 24 to the mounting 11. The handle 23 carries a cam lock 25 which can be engaged over the upper end of the backbone 9 to locate the handle in its pushing position.

A flexible fabric bucket seat 26 is mounted on the front supports 5 by means of sleeves 27. In conventional manner the seat may be provided with a harness belt 28.

One rear wheel, is as shown in FIG. 2, provided with a brake 29 operated by a handle 30.

The chair is locked in the erect position shown in FIGS. 1 and 2 by means of the lock 25. To fold down the pushchair, the lock 25 is released and the handle 23 is folded backwards and downwards relatively to the backbone 9. This movement coupled with the reaction in the link 24 causes the mounting 13 to slide up the backbone relatively to the mounting 11 carrying the upper ends of the front and rear supports 5 and 6 with it. As a result the links 14 and 17 fold upwards about the mounting 16 and the supports move close to the backbone with the wheels 7 adjacent to one another as shown in FIG. 4. In the fully closed position the end of the carrying handle 23 snaps behind a hood 31 which is shown in FIG. 2. The reverse procedure is adopted to reerect the pushchair.

When the pushchair is being folded the centre link of the chain 20 moves downwards as the inner ends of the footrest links 21 fold downwards about their pivotal connections to the mountings 8. The chain 20 always folds downwards, rather than upwards, because when unfolded it is held below a dead centre position by abutments formed by the inner ends of the links 21 egaging the underside of the web of the centre link, which is downwardly channel-shaped. In the erect position the strap 22 is in tension holding the abutments between the links 21 and the centre link hard against one another, thus contributing appreciably to the strength and stability of the frame.

Claims

We claim:

1. A folding wheeled frame for a pushchair comprising

an upwardly extending backbone,

two front and two rear upwardly extending supports, each of which carries a wheel at its lower end,

separate pivotal links connecting each of said supports adjacent their lower ends to a first fixed point near the lower end of said backbone,

additional separate pivotal links connecting each of said front supports to a second fixed point on said backbone above the lower end of said backbone,

a mounting movable longitudinally along said backbone above said second fixed point, and

a pivotal connection between each of said supports and said mounting,

whereby upward movement of said mounting relative to said fixed points will draw said supports upwardly and inwardly toward said backbone as said links swing about said fixed points.

2. A frame according to claim 1, in which the upper ends of said rear supports are pivotally connected directly to said mounting.

3. A frame according to claim 2, in which said pivotal connection is a further pivotal link connecting said mounting to each of the links connecting the upper ends of the front supports to said second fixed point.

4. A frame according to claim 1, comprising two arms one of which is pivoted to said mounting and the other of which is pivotally connected to said second fixed point, one of said arms being connected to the other at a point intermediate its length so that said other arm constitutes a lever capable of moving said mounting toward or away from said fixed point.

5. A frame according to claim 4, in which the lever is pushing handle for said pushchair.

6. A frame according to claim 5, comprising a swing camlock latch positioned to hold said backbone in the erect position, said handle folding downwards alongside the backbone in the folded condition.

7. A frame according to claim 1, comprising a folding pivotal link directly between the lower ends of said front supports.

8. A frame according to claim 7, in which the centre point of said folding link is attached to the lower end of said backbone by means of a strap.

9. A frame according to claim 1, in which the backbone is L-shaped with its lower end extending forwards, said four pivotal links from adjacent to the lower ends of said four supports being pivotally connected to said backbone adjacent to the front end of said forwardly extending portion of said backbone, the lower ends of said rear supports being also connected by means of pivotal links to said backbone just above the bend in said backbone.

10. A frame according to claim 9, in which said pivotal links attached to said forwardly extending backbone portion are attached through universal joints, each consisting of plates having opposed apertures in which a ball end fixed to said pivotal link is sandwiched.

11. A frame according to claim 1, supportingly connected to a bucket seat.