GB2499048A

GB2499048A - Sledge with directional and speed control

Info

Publication number: GB2499048A
Application number: GB1202031.9A
Authority: GB
Inventors: Nicholas Charles Loxton
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-02-06
Filing date: 2012-02-06
Publication date: 2013-08-07
Also published as: GB201202031D0

Abstract

A sledge comprises a platform supported on each side by one or more legs connected to flexible runners, where the legs comprise rotational joints and the runners may be flexed or rotated by means of handles attached thereto. The joints may be made from rubber or similar flexible material, and may be provided with centralising springs and adjustable stops so that the degree of rotation of the runners may be varied. The joints may also have a quick release mechanism so that the runners may be removed or changed. The platform may comprise a rigid element with front and rear portions which are angled upwards, and rails to either side against which a user may brace their thighs when lying on the platform. The handles of the sledge may be operated by hand when a person is lying on the sledge or by a persons feet if they are sitting down.

Description

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Description

This invention relates to a new design of ice/snow sledge [sled] in which speed and directional control is applied via flexible or rotational joints between the body of the sledge and the runners.

The rigid framework (platform) has been designed for the rider to lie on the stomach with his [= 'his' or 'hers', throughout] head forward, but the rider can operate the sledge from a seated position if preferred. The ergonometric design of the platform increases rider comfort and reduces stress on the rider's body: the front of the platform is raised (fig 1a) to elevate the chest, reducing neck strain when looking forward, and its level profile allows the rider to move his body to the left and right without hindrance to facilitate weight transfer whilst cornering.

At the rear of the platform is a cushioned cross member (fig 1 b) which is slightly raised to provide leg support which reduces strain on the rider's body. It has also been designed to act as a fulcrum allowing the feet to be raised and the knees lowered for free motion or the feet to be lowered and the knees raised if extra control is required.

Towards the rear of the platform there are two vertical hoops (fig 1c), one either side of the platform, so positioned that the rider can lock his lower body onto the sledge by spreading his thighs.

The platform is supported on each side by one or more legs which are connected to the runners at or near the centre of each runner via mechanical rotational joint or a rubber joint, or some-other similar flexible material. The joints may be fitted with or without stops, which can also be adjustable to limit the degrees of tilt the runners can achieve in either a clock-wise or anti clock-wise direction. The joints can also be fitted with or without a centralizing spring, that returns the runner to a central (level) position on the ground when the handles are released. These joints enable the rider to rotate the runners about the axis of the joint and tilt them in relation to the ground so that only the edge of one or both runners is in contact with the ground (Fig 2a). The front and rear ends of the runners are not connected to the platform, thus enabling the runners to flex freely. A control handle, lever or pedal is fitted to each runner shaped in such a way that it can be operated by hand or by foot (fig 2b)

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The runners are upturned at the front and are so profiled and shaped that they are wider at the front and rear and narrower towards the centre (fig 2c). With the runners flat on the ground and unladen, only the front and rear of the runner will be in contact with the ground, this is because, when manufactured the runners are built with a at rest arc. The arc will flatten when weight is applied, and this puts more weight at the ends of the runners to help responsiveness. The widths of the profiles arcs and the lengths of the runners will vary according to the way the sledge is to be used. The runners are flat and smooth and their bottom edges are fitted with sharp square steel edges to give directional and braking control on ice and snow. The runners are flexible to allow them to follow the contours of the ground and to give directional control.

Directional control is achieved by using the handles [= 'handles, levers or pedals, throughout] to rotate the runners, thus tilting them in relation to the ground. When this happens the weight of the sledge and rider is transferred to the wider front and rear sections of each runner, thereby lifting the narrower centre sections off the ground (fig 3 a, shows the runners being tilted to initiate turning). However because the runners are flexible their centre sections will curve under the weight of the rider and sledge, and so their edges will remain in contact with the ground. When the sledge is moving forward at speed the tilting and consequent curving of the runners effects directional change. The sledge starts to veer to one side but the momentum of sledge and rider carries on in the original direction causing a build-up of lateral forces on the runners. Ever-increasing force acts on the side of the runner which is tilted against that force: the weight and momentum of the rider and sledge pushes the centre section of the runner into the curve, thereby forcing the wider sections of the runners (the front and rear sections) into a tighter curve (fig 4 a, shows the runners being forced into a curve). The greater the degrees of tilt, the greater the forces on the runner, which means the greater the curve, and the wider the profiles at the ends of the runners, the greater the forces, the greater the curvature, the tighter the turning effect.

There are three methods of speed control. The first method is to push the handles forward, thereby creating pressure points at the front of each runner and slowing their progress through the snow. The second method is to turn the two handles in towards each other: the flexibility of the runners and the forces acting upon them (as described earlier in the section on directional control) causes them to take the form of a snow plough, thereby slowing the sledge (fig 5 a, shows the runners in a snow plough shape for

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speed control). The third method is by turning both handles either to the left or right so the sledge starts to turn (as describe earlier in directional control). If the tilt is maintained the sledge will go into a relatively tight turn until it is at 90 degrees to the direction of travel. At this point the sledge will only have very limited movement in the direction the sledge is now facing because the turn is too tight, and the mass of the rider has to much momentum and velocity in the original direction of travel, the result is that the sledge will still travel in the same original direction, but will do so side on to the direction of travel. While the runners are tilted with only their edges in contact with the surface there is a build-up of friction and resistant force which will slow the sledge and bring it to a halt (fig 4 a, show the runners curving under the forces).

The directional and speed control on this sledge is simple and cost effective to produce with the minimum of moving parts. A shaped, flexible, springy material is used for the runners while the joints between the runners and the sledge allow rotational and lateral movement. Directional control is simply achieved by twisting the runners via the fitted handles. Speed control is similarly simple: pushing the handles forward will moderate the speed slightly while pulling the handles together and forward will reduce the speed more sharply. Turning the sledge into a sharp turn will cut the speed dramatically, allowing the rider to zig-zag down a steep slope, while maintaining a very sharp turn will bring the sledge to an abrupt stop.

Claims

4 Qaims

1. A sledge comprising a platform connected by means of rotational jointsto flexible runners which can be rotated and caused to flex by handles attached to the runners.

2. A sledge according to claim 1 where the joints to the runners are made of rubber or similar flexible material.

3. A sledge according to claim 1 where the joints are fitted with one or more centralizing springs.

4. A sledge according to claim 1, 2 and 3 where one or more joints are fitted with stops to restrict the degrees of rotation the runners have about the axis of the joint.

5. A sledge according to claim 4 where the stops are adjustable, where the degrees of rotation can be varied.

6. A sledge according to either of the preceding claims with raised railson either side of the platform level with the rider's thighs.

7. A sledge according to either of the preceding claims in which the rotational joints are fitted with a quick release mechanism so that the runners maybe removed or interchanged.

8. A sledge according to any of the preceding claims in which the front end of the platform is angled upwards.

9. A sledge according to any of the preceding claims in which the rear end of the platform is angled upwards.

10. A sledge according to any of the preceding claims in which pedals are attached to the handles so that they can be operated by foot pressure.