GB2478340A

GB2478340A - Hand-propelled vehicle with resiliently mounted further wheel for cushioning

Info

Publication number: GB2478340A
Application number: GB1003622A
Authority: GB
Inventors: Nazim Ibne Joomun
Original assignee: JOONA Ltd
Current assignee: JOONA Ltd
Priority date: 2010-03-05
Filing date: 2010-03-05
Publication date: 2011-09-07
Anticipated expiration: 2030-03-05
Also published as: GB2478340B; GB201003622D0

Abstract

A hand-propelled vehicle such as a push chair 12 has a further wheel 2 carried on a rearwardly-mounted downwardly-extending spring-loaded shaft and projecting below the ground plane P. The further wheel cushions the impact of the step surface 4 against the rear wheels W as the push chair is wheeled down the steps. The vehicle may optionally be a wheelchair.

Description

Hand-propelled Vehicle The present invention relates to a hand-propelled vehicle such as a push chair or perambulator or the like (such as a buggy or stroller for example) or a wheelchair

for example.

Such vehicles are designed to be wheeled over flat surfaces such as pavements or floors but in practice somctimcs have to be carried up or down stairs, usually with the child or adult occupant in the vehicle. When eg a push chair is taken down a flight of stairs, the adult wheeling the push chair will either require assistance from another person to help carry it down, or lower it down as gently as possible using the rear wheels. This second option typically involves the child occupant experiencing an impact at the bottom of each step. This is highly inconvenient and uncomfortable for both the adult and the child because the suspension is usually rudimentary or non-existent.

An object of the present invention is to alleviate the above problem.

Accordingly the invention provides a hand-propelled vehicle having rear and optionally front wheels defining a common ground plane tangential to the wheels and having at least one further wheel mounted on a resilient mounting, the resilient mounting allowing the further wheel to project beneath the ground plane and cushion the vertical impact on the vehicle when the vehicle is wheeled over a step.

In this manner the further wheel on the resilient mounting co-operates with the rear wheels and distributes and cushions the shocks caused by the vehicle traversing the steps.

Normally there will be two such further wheels disposed at either side of the vehicle.

Preferably said vehicle has front wheels and at least one further wheel is mounted at the rear of the vehicle. This enables the vehicle to be cushioned when it is wheeled forwardly over the steps.

Preferably said at least one further wheel is securable into a retracted position in which it does not project beneath said ground plane. This feature has the advantage that the further wheel will not impede the braking mechanism or wheeling of the vehicle over non-stepped but rough surfaces, even if it is (desirably) of smaller diameter than the front and rear wheels.

Preferably said resilient mounting comprises a telescopic tube enclosing and urged into an extended configuration by a spring and carrying a said further wheel at a lower end of the tube. This feature has the advantage of protecting the spring and allowing a relatively large travel of the further wheel or wheels.

Preferably the vertical travel of a said further wheel beneath said ground plane is greater than the diameter of said further wheel. This combination of large travel and small diameter enables the further wheel to run along the top surface of each step and support the vehicle as it does so.

Preferably said vertical travel is at least the diameter of said further wheel.

Conveniently, a said resilient mounting is secured to a strut of said vehicle carrying a said front or rear wheel.

Preferred embodiments of the invention are described below by way of example only with reference to Figures 1 to 11 of the accompanying drawings, wherein: Figure 1 is a diagrammatic side elevation of a rear wheel and further wheel arrangement of a vehicle in accordance with the invention, the further wheel being in an initial retracted configuration; Figure 2 is a similar diagrammatic side elevation showing the further wheel in a deployed (released) configuration; Figure 3 is a diagrammatic side elevation showing the ifirther wheel mounting in its frilly extended configuration as the rear wheel is wheeled over a step; Figure 4 is a diagrammatic side elevation showing the compression of the frirther wheel mounting as the rear wheel descends the step; Figure 5 is a diagrammatic side elevation showing the rear wheel and further wheel at the foot of the step; Figure 6 is a diagrammatic side elevation similar to Figure 1 showing the rear wheel once again in a retracted configuration; Figure 7 is a diagrammatic end elevation, partly cut away, showing the ftirther wheel mounting of Figures 1 to 6 in more detail; Figure 8 is a diagrammatic end elevation, partly cut away, showing a variant of the frirther wheel mounting which utilises a tension rather than a compression spring; Figure 9 is a diagrammatic side elevation showing the further wheel mounting in a retracted configuration; Figure 10 is a diagrammatic side elevation which shows a wheelchair in accordance with the invention utilising the further wheel arrangement of Figures 1 to 6, and Figure 11 is a diagrammatic side elevation which shows a push chair in accordance with the invention utilising the further wheel arrangement of Figures 1 to 6.

Referring to Figure 1, the arrangement shown comprises a right-hand rear wheel 1 contacting a step surface 4 and mounted on the lower end of a rear strut 5 of a hand-propelled vehicle, and an upright telescopic tube having a spring-loaded sliding inner tube or shaft portion 3 mounted within an outer tube portion 7 and carrying a further wheel 2 whose rotary axis is parallel to that of the rear wheel 1. The rear side of outer tube portion 7 is attached to a mounting plate 8 which has lugs 6 releasably secured (eg by self-tapping screws, not shown) to strut 5.

In the configuration shown in Figure 1, the further wheel 2 and its associated inner tube portion 3 are secured in a retracted configuration by a handle mounted latch 9 and pin 10 which is mounted to the inner tube or shaft portion 3(Figure 7/Figure 8/ Figure 9).

Referring to Figure 2, the inner spring-loaded tube portion 3 is released by manually rotating the handle mounted latch9 and hence further wheel 2 is resiliently urged against the step surface 4.

As the vehicle is wheeled forward, ie to the right in the drawing, the rear wheel 1 approaches the edge of the step and, as shown in Figure 3, after the further wheel 2 rolls over the edge of the step it is extended downwardly by its associated spring below ground plane P by a distance T. Ground plane P is the common tangential plane at ground level of the front and rear wheels of the vehicle. Distance T is preferably at least 30 mm and is preferably at least the diameter of further wheel 2, but is typically less than the height of the step.

As shown in Figure 4, after the rear wheel 1 rolls over the step, the further wheel 2 falls to the lower part of step surface 4 and the spring loading of inner tube portion 3 cushions the shock of this until the rear wheel 1 reaches the lower part of step surface 4 as shown in Figure 5. In order to provide a substantial cushioning effect, the spring loading of inner tube portion 3 is preferably sufficient to support at least 10%, preferably at least 30% and more preferably at least 45% of the vehicle's rated load (eg a typical passenger) and weight when the front and rear wheels and further wheel 2 are all standing on the ground plane (ie corresponding to the condition shown in Figure 5).

Finally, when all the steps have been negotiated, the inner tube portion 3 is raised manually until the handle mounted latch 9 is able to enclose the pin 10. The latter then springs out to hold the arrangement in the retracted configuration shown in Figure 6, which is identical to the configuration shown in Figure 1.

It should be understood that the left-hand rear wheel (coaxial with the right-hand rear wheel 1, and not shown) is provided with an arrangement essentially identical to that shown in Figure 1, to which the above specific description is equally applicable. In a variant, a single resiliently-mounted further wheel 2 could be provided, rather than two such further wheels as in the above embodiment. The single resiliently-mounted further wheel could be located midway between the left and right rear wheels for example. The axial dimension of the or each further wheel is not critical and can be greater than or less than its diameter, for example.

Figure 7 shows a rear elevation of the telescopic tube arrangement including a compression spring CS which acts downwardly in direction A between a closed upper end of outer tube portion 7 and cap 3Aon the upper end of inner tube portion 3. Cap 3A is of larger diameter than the remainder of inner tube portion 3 and is accommodated in a complementary stepped portion of outer tube portion 7 at the lower extremity of travel as shown.

Figure 8 shows a variant in which a tension spring TS acts between cap 3A and the lower stepped portion of outer tube portion 7, again in direction A. Figure 9 shows a side elevation of in which the telescopic tube arrangement is held in a refracted position by the handle mounted latch 9 and pin 10.

Figure 10 shows a wheelchair 11 having conventional rearwardly-extending handles and incorporating the sprung telescopic tube arrangement of Figure 7 or Figure 8. It will be seen that the resiliently mounted further wheel 2 will reach the step surface 4 before the rear wheels W of the wheelchair and therefore substantially cushion the resulting shock. The telescopic tube arrangement is shown at the fullest extent of its travel with further wheel 2 projecting substantially below ground plane P. Figure 11 similarly shows a push chair 12 being wheeled forwardly down steps, with the further wheel 2 again projecting below ground plane P and about to cushion the impact of the step surface 4 against the rear wheels W. The push chair is provided with conventional rearwardly-extending handles.

Although the above embodiments employ a telescopic tube arrangement for the resilient mounting, other resilient mountings such as cantilevered mountings could be employed. Furthermore one or more resiliently-mounted further wheels could be placed near the front wheels instead of or in addition to near the rear wheels to enable the vehicle to be wheeled backwardly down steps.

Although the invention is particularly applicable to a conveyance for children or adults, it is not essential for the vehicle to include a seat. The vehicle could for example be a trolley, eg for carrying delicate goods. The vehicle could also be a hand truck having only one pair of wheels.

Claims

Claims 1. A hand-propelled vehicle having rear and optionally front wheels defining a common ground plane tangential to the wheels and having at least one further wheel mounted on a resilient mounting, the resilient mounting allowing the further wheel to project beneath the ground plane and cushion the vertical impact on the vehicle when the vehicle is wheeled over a step.
2. A hand-propelled vehicle according to claim 1 wherein the vehicle has front wheels and said at least one further wheel is mounted at the rear of the vehicle.
3. A hand-propelled vehicle according to claim 1 or claim 2 wherein said at least one further wheel is securable into a retracted position in which it does not project beneath said ground plane.
4. A hand-propelled vehicle according to any preceding claim wherein said resilient mounting comprises a telescopic tube enclosing and urged into an extended configuration by a spring and carrying a said further wheel at a lower end of the tube.
5. A hand-propelled vehicle according to any preceding claim wherein the vertical travel of a said further wheel beneath said ground plane is greater than the diameter of said further wheel.
6. A hand-propelled vehicle according to claim 5 wherein said vertical travel is at least the diameter of said further wheel.
7. A hand-propelled vehicle according to any preceding claim wherein said resilient mounting has a spring loading sufficient to support at least 30% of the vehicle's rated load when the front and rear wheels and further wheel are all standing on said ground plane.
8. A hand-propelled vehicle according to any preceding claim wherein said resilient mounting has a spring loading sufficient to support at least 45% of the vehicle's rated load when the front and rear wheels and further wheel are all standing on said ground plane.
9. A hand-propelled vehicle according to any preceding claim wherein a said resilient mounting is secured to a strut of said vehicle carrying a said front or rear wheel.10. A hand-propelled vehicle according to any preceding claim which is a conveyance having a seat for a passenger.9. A hand-propelled vehicle according to any of claims 1 to 9 which is a push chair or pram or the like, or is a wheelchair.
10. A hand-propelled vehicle substantially as described hereinabove with reference to Figures 1 to 6 and 9 in conjunction with Figure 7 or Figure 8 and in conjunction with Figure 10 or with Figure 11 of the accompanying drawings.