GB2219774A - A friction mat for overcoming wheel slip - Google Patents

Abstract

A friction mat for overcoming wheel skids comprises a rectangular planar member 10 having an edge section 12 of tapering cross-section to allow initial insertion between a wheel and a surface, and a main part 11 formed as a grid with longitudinal bars 13 and lateral bars 14. A plurality of rotatable eccentrically mounted friction members 19 are carried on lateral rods 20 and have teeth 21 which are exposed to both the upper and lower surfaces of the mat. The imposition of weight on the mat causes the members 19 to partially rotate to increase their friction with the surface and wheel. Various shapes of member 19 are illustrated. In an alternative form, not illustrated, the members 19 are moulded integrally with the mat and are displaced by deformation to achieve the increase in friction. <IMAGE>

Description

A Friction Mat for Overcoming Wheel Skids This invention relates to a friction mat for overcoming wheel skids, for use in extricating vehicles which are immobilised by skidding in ice, snow, mud, sand, or other situations where wheels cannot grip on the surface with which they are in contact.

Stranding of vehicles due to skidding and ensuing wheel spin is not uncommon, particularly in ice and snow, but also in liquified mud, loose sand and similar conditions. It is usual to attempt to extricate the vehicle from such a situation by placing some frictional between the wheel and the skid surface for example any material handy such as loose rubber foot mats from the vehicle, sacks, clothing, any wood which can be scavenged, or particulate material such as gravel, stones and the like. All these measures are essentially ad hoc, and not usually considered in advance, although a farmer might carry a few old sacks in his off-road car for such a purpose. There has moreover, to the applicant's knowledge not been any proposal of any device which can be carried conveniently in a vehicle which has been expressly designed for use in such an emergency.

An object of the invention is to provide a friction mat which can be used to place between the wheel of a skidding car and the surface to which the wheel is failing to grip, in order to create friction between the wheel and mat on one hand, and the mat and surface on the other.

According to the invention therefore, there is provided in its simplest form, a friction mat for overcoming wheel skids comprising a generally planar member provided with a plurality of friction members disposed to be effective on both surfaces of the planar member so that the mat can be interposed between a wheel and surface, and frictionally engage both.

Preferrably, the mat includes an edge portion having a rough upper surface, for example with ribs or studs, for forming a 'lead-in' for presentation to and entrainment between the wheel and ground. The planar member rerrably also comprises a main part, which may be formed as a grid or mesh to enable mud or water etc. to drain through. The planar member is also preferrably provided with a plurality of friction members which may for example be rotatable bodies mounted on the main part, teach preferrably mounted on an assymetrical axis and each provided with a plurality of peripheral teeth or other project ònr.

Alternatively, the friction members may be moulded integrally with the planar member, and be of a flexible material which allows sufficient distortion to acheive a grip.

The friction members, referred to hereinafter as 'lugs' for the sake of brevity, can be of any of a variety of shapes, for example, triangular, eliptical, 'tadpole' or 'comma' shaped, kite or heart shaped. The lugs may be journalled on grid members of the main part and be perpendicular to the plane of said main part, presenting an array of teeth or projection to each surface of the mat.

It is intended that the edge portion be presented into the gap between a vehicle wheel and the ground, and become entrained therebetween, drawing the main portion of the mat below the wheel, The projections on the lugs which are presented upwards provide a purchase for the wheel and the rotary force of the wheel drive also rotates the lugs thereby applying force to the downwardly presented projections, force which helps them to grip the slippery surface.

A preferred embodiment of friction mat according to the invention will now be described by way of example, with referrence to the accompanying drawings, wherein: Fig. 1 is a general plan view of a friction mat according to the invention; Fig. 2 is a sectional view of the leading edge of the mat of Fig. 1; Fig. 3 is a detail sectional view of part of the main portion of the mat; and Figs. 4a - 4c show various shapes of lugs for mounting in the mat.

As shown in the drawings, a friction mat according to the invention for overcoming wheel skids by being interposed between a wheel and a surface, a separate mat being useable for each wheel, is a generally planar member 10, having a main portion 11 and a lead-in edge portion 12. The main portion 11 is a grid or mesh of longitudinal bars 13 and latteral bars 14.

The edge portion 12 is a wedge in cross-section, tapering tothe extreme edge, and comprises a web having ribs or projections 15 on at least the upper surface. In a preferred embodiment metal nails or studs 16 pass through the web with heads 17 protruding from the upper surface, and points 18 extending below the lower surface.

In the main portion 11, a plurality of lugs 19 are rotatably mounted between the longitudinal bars 13 of the grid on rods 20 which extend through the bars 13 from one side of the grid to the other. The lugs 19 are metal bodies provided with projections or teeth 21 about their edges. The lugs may be triangular, as shown in Fig. 3, or may be any one of the shapes shown in Figs 4a -4c, i.e. an elongated elipse (Fig.

4a), a 'comma' or 'tadpole' (Fig 4b), or kite shaped (Fig.

4c). All are however journalled assymetrically, so that when subject to pressure and rotational force below a vehicle wheel, they will partially rotate and bite into the surface, but will not continue rotating and begin to spin as might occur with discs, thus avoiding further skidding.

The friction mat operates to end skidding by increasing the surface area over which the wheel pressure is applied, and by providing a purchase between the wheel and surface, by means of the projections on the lugs which dig into the wheel and ground. The vehicle can thus be extricated from an immobilising wheel spin caused by ice, snow, sand, mud etc.

with some wear to the tyre rubber, using the friction mat of the invention. A set of two mats might be carried in a car boot, one for each drive wheel of a standard car. The nat may measure for example 30 x 40 cm. For use with heavier vehicles, such as lorries, the whole main grid part wouid be made more massive, possibly of metal links articulated on the transverse rods rods to retain flexibility, and the lugs 19 being in the form of toothed or riged rollers to avoid crushing. Further the edge portion of the mat could be formed from a plurality of interlinking transverse members, each having a groove along one face to receive a rib along the abutting face of an adjacent member, the non-abutting faces being provided with ribs or projections. The transverse members may be decreased in size towards the leading edge of the mat, where first contact between wheel and mat is made.

In a simplified embodiment, not shown, the rotatable lugs are dispensed with and the tops and bottoms of the transverse and longitudinal bars are formed with teeth or projections.

The grid could alternatively be formed with diagonal members. The main part of the mat may be fabricated from a suitably strong and flexible natural or synthetic rubber or plastics material. The lugs may be of steel or other robust and flexible material.

The lugs may be non-rotatable and moulded integrally with the mat, thus avoiding assembly steps in manufacture. The mat may be of a flexible material such that the weight of a vehicle will distort the lugs and thus displace parts thereof to acheive a grip.

Claims (7)

Claims

1. A friction mat for overcoming wheel skids comprising a generally planar member provided with a plurality of friction members disposed to be effective on both surfaces of the planar member so that the mat can be interposed between a wheel and a surface, and frictionally engage with both.

2. A mat according to Claim 1 including an edge portion having a rough upper surface for forming a lead-in for presentation to and entrainment between the wheel and surface.

3. A mat according to Claim 2 wherein the planar member comprises a main part formed as a grid or mesh and carrying a plurality of friction members each of which is a body which is at least partially displaceable under pressure, and provided with a plurality of peripheral teeth or other projections.

4. A mat according to Claim 3 wherein the friction members are integrally formed with the mat, and are deformable under pressure to increase the friction of the mat between the wheel and surface.

5. A mat according to Claim 3 wherein the friction members are each rotatable bodies mounted on grid members of the main part perpendicular to the plane of the mat, and pivoted on an axis which is offset from the centre of gravity of the respective friction member.

6. A mat according to Claim 1 which comprises a rectangular planar member having an edge section of tapering cross-section to allow initial insertion between a wheel and a surface, and a main part formed as a grid with longitudinal bars, and latteral bars, a plurality of eccentrically mounted friction members being carried on 2 : latteral rods, and having teeth which are exposed to both the upper and lower surfaces of the mat, whereby the imposition of weight on the mat causes the members to partially rotate and increase their friction with the surface and wheel.

7. A friction mat for overcoming wheel skids substantially as hereinbefore described with reference to and as illustrated in Figs.l and 2, and any of Figs 3 and 4a to 4c.