GB2452563A - A sled with a plurality of overlapping wheels - Google Patents

Abstract

A sled for use on dry land, having a plurality of wheels 8 mounted on runners 5 fixed under a load bearing platform 1. The wheels are located on alternate sides of the runners, such that their axle spacing is less than one wheel diameter apart (figure 3), allowing the sled to ride over uneven surfaces. Additionally, a combined steering and braking mechanism 2-4 operated via a control handle 2 or bar allows the runners to both flexibly deform left or right enabling the rider to steer (figure 4) and to deform inwardly to effect a braking action (figure 5) to slow the sled.

Description

ROLLER SLED WITH STEERING AND BRAKING

MECHANiSM

FIELD OF THE INVENTION

The present invention relates to sleds, specifically to a roller sled to operate without the presence of snow or ice providing improved ride and control.

BACKGROUND/DESCRIPTION OF PRIOR ART

Sleds are normally used for pleasure or for the transport of food, equipment or supplies in conditions where snow and ice are found. Most existing snow and ice sled designs have derived from either a ridged plate under the load bearing platform to spread the weight of the load, called a planing sled, or use two or more runners under the load bearing area to cut into the snow or ice, called a runner sled. Steering mechanisms for both designs have been developed and feature either an articulated set of short skis in front of a planning sled design or the use of flexible runner material that can be bent to steer the runner sled design.

When snow and ice are not present the friction created by these designs is too high for the sled to move freely. This has led a number of designs that provide sleds mounted on rollers or wheels. The heretofore proposed inventions suffer from several disadvantages that have prevented their widespread commercial and pleasure use, in particular relating to the arrangement of the wheels and the control of the sled by steering and braking.

In the designs for roller sleds that mount a consecutive series of rollers or wheels on a runner sled, such as in the invention described by Ress in WO 2004/062979 Al and by Walker in US 2003/0197341 Al, the arrangement of the wheels causes problems with the smoothness of the ride when running across a surface, particularly if the irregularities in the surface caused by lumps and bumps in the ground are of a similar size and spacing to the wheel diameters used. As the sled moves over the uneven surface each bump on the ground is met successively by each wheel causing the sled to rise and fall and resulting in an irregular and jarring ride.

One way in which comfort can be improved is to reduce the distance between the wheels by providing more wheels. With an in-line arrangement the rollers or wheels cannot be moved closer than one wheel diameter spacing and if the wheel/roller diameter becomes too small, the sled does not ride well over rougher surfaces and is likely to suffer grounding on larger bumps or jamming caused by ground debris caught between the wheels or the sled body. Current designs therefore trade the diameter of the rolling wheels between rider comfort and ground clearance.

For safety and practicality it is desirable to incorporate steering and braking mechanisms to control the roller sled. ln a design described by Twitchell in international Publication Number WO 2004/087481Al steering control has been added to a runner sled by using flexible runners mounted on hinges that are deformed by an articulating seat mechanism acting near the centre of the runner length. This mechanism has also been applied to a sled with wheels mounted at either end of the runners. A previous patent US 4046392 has approached the steering problem by using a hinged lever arm to bend the front of the runners on a conventional runner sled design equipped with wheels to provide a steering effect. In the inventions described by Ress in WO 2004/062979 Al, Berliner in US 7021636 B I and Reid in CA 1073494 a braking effect is provided on a wheeled sled by applying a friction surface to the rollers or wheels. With all these approaches, the complexity of the design and number of components is likely to lead to increased manufacturing costs for mass production purposes.

DESCRIPTION OF THE INVENTION

The invention is now described by way of example only in accordance with one embodiment with reference to the accompanying drawings in which: Figure 1 illustrates a perspective view of an embodiment of the invention showing its main features.

Figure 2 illustrates a side view elevation of the alternating wheel arrangement for a single runner.

Figure 3 shows a top view elevation of Figure 1 detailing the steering and braking control assembly.

Figure 4 illustrates a top view elevation of the apparatus in Figure 1 and Figure 3 initiating a right turn.

Figure 5 illustrates a top view elevation detailing the same apparatus initiating a braking control.

As shown in Figure 1, The assembly of the roller sled comprises a horizontal load bearing surface/platform (1) attached by a rigid framework of vertical supports (7) at two or more points along its length via flexible rubber or polymer mounting bush (6) to two or more parallel runners (5) sufficiently far apart to provide for a stable sled and with each runner set at a parallel distance apart when the sled is stationary and not carrying a load. Each runner is constructed from a suitably flexible material and has an upraised leading tip such that the two leading wheels do not touch the ground when the sled is stood on a horizontal surface. Each runner is equipped with a plurality of free running wheels (8) fixed to alternate sides of it such that the axle spacing of each wheel is less than one wheel's diameter. The steering and braking assembly is comprised of a flat or tubular control surface (2) attached rigidly at right angles to the control shaft (3). The control shaft is vertically hinged at its rear end onto said platlbrm by a bolt, pivot or pin. The same shaft is vertically hinged at its forward end by a bolt, pivot or pin onto a pair of symmetrical tie bars (4) that are in-turn vertically hinged at their outmost ends onto single vertical supports (9) at the front end of each runner by a bolt, pivot or pin. The component parts on the right side of the sled are identical to those on the left side but are configured as a mirror image.

In this embodiment it is intended that the operator of the roller sled should sit upright and provide input to steer or brake through the control surface using either their hands or feet, but in other embodiments the operator may choose to lie prone on their front or back, or to operate the control surface with their feet, or to stand upright on the load bearing surface.

Referring to Figure 4 and in this embodiment the action of moving the left hand side of the control surface forwards causes a turning action the control shaft to pivot around its vertical hinge at the platform end. The runners, which are linked by the tie bars at the front end of the control shaft, and due to their flexible mountings against the rigid frame, can flexibly deform in parallel with each other towards the right along the majority of their length, thus initiating the sled to steer right. By the very same method, moving the right hand side of the control surface lbrwards enables the sled to steer towards the left.

Referring to Figure 5 and in this embodiment the control assembly provides fur the control surface to be moved forward or backwards via the action of the telescopic control shaft. When the roller sled is running in a straight line, moving the control surface ibrwards or backwards has the effect to lengthen or shorten the control shaft.

The hinged connection between the control shaft and the tie bars and the left and right runners has the effect of reducing the distance between the front tips of the runners so that they are pulled towards each other and the centre of the sled, flexibly delbrming the runners along their length so they are no longer operating in parallel with each other. This has the effect of increasing the, friction of the wheels against the ground providing a braking action similar to that of performing a snow plough manoeuvre when skiing.

Preferably, the load bearing platform comprises a one-piece design to minimise production costs.

Preferably, the construction of the load bearing platform, horizontal control surface and vertical runner supports should comprise a rigid material such as certain co-polymers, reinforced co-polymers, laminated woods or metals. These materials allow the production of a lightweight but stiff structure with low manufacturing costs.

Alternatively, more flexible materials may be used but these may require further structural design features to create a suitably rigid platform.

Preferably, in this embodiment the control shaft and tie bars comprise a stiff material such as reinforced co-polymers or hollow metals of a suitable diameter and wall thickness to provide a rigid steering/braking assembly.

Alternatively, the horizontal control surface may be substituted or supplemented by a rigid vertical shaft or equivalent, similar to a joystick or handlebar.

Alternatively, the telescopic action of the control shaft may be substituted or supplemented by other mechanisms such as mechanical springs, hydraulic devices or elastic polymers to minimise mechanical complexity and improve the reliability and operation of this mechanism and to minimise production costs.

Preferably, each runner comprises of a single flexible co-polymeric strip such as polyethylene or polypropylene. Alternatively, other materials such as thin metals or laminated wood may be used.

Preferably, the thickness of each runner is varied in accordance with the overall length of the runner and the required amount of flexibility required in accordance to the material type used in its construction.

Preferably, the height of each runner should be determined in accordance with the wheel diameter to prevent the wheel from interfering with the platform and to provide adequate ride height to prevent the platform from becoming obstructed by bumps in the ground.

Preferably, the flexible mountings between the load bearing platform and each runner should comprise a moulded natural rubber or polyurethane bush that can deform in response to the deformation incurred along the length of each runner.

Prefrably, the wheels should comprise a suitable polymer or metal based hub assembly mounted with bush, sealed or unsealed cartridge bearings to provide free running operation. Alternatively, in a simplified lbrmat to reduce cost and weight, the wheels should rotate directly around their axle, preferably gaining advantageously from the low friction properties provided by certain polymers e.g. Polytetrafluoroethylene (PTFE) or metal alloys e.g. brass.

Preferably, the wheel hub assembly should have pneumatic or solid tyres of natural or synthetic rubber or co-polymeric material such as polyurethane to improve rider comlbrt. Alternatively, the wheel may comprise of a single rigid metal, metal alloy or plastic disc with no cushioning.

Furthermore, the wheels may be chosen to be larger or smaller in diameter, or wider or narrower as is determined advantageous to the intended ground surface and weight of load carried. The number of wheels may be increased or decreased according to their diameter in relation to the overall length of the sled runners.

Claims (5)

1. What is claimed is: I. A roller sled fbr transport or leisure purposes comprising one or more parallel runners mounting a plurality of free running wheels; wherein the axles for each wheel are evenly spaced such that when the wheels are arranged on opposite sides, each wheel is less than one diameter apart and each wheel overlaps with the next on the opposite side.
2. 2. A roller sled with a plurality of free running wheels according to claim I attached to runners of a flexible material.
3. 3. A roller sled according to claim I, wherein the steering and braking input comprises a horizontal control surface attached to a control shalt that articulates, extends and contracts with respect to the main body of the sled and is linked to the runner tips via horizontal tie bars.
4. 4. A roller sled according to any of claims I to 3 capable of carrying one or more passengers in a seated, prone or standing position.
5. 5. A roller sled according to claim I capable of being controlled via a mechanical assembly operated by either the rider's hands or feet.