GB2122097A - Skis - Google Patents

Abstract

A ski for use especially on artificial ski-slopes has a sole provided by a layer (5) of nylon filled with molybdenum disulphide. Unfilled nylon or nylon filled with graphite may be used alternatively. The ski may be of generally-conventional construction with or without metal edging strips (7), the sole having a plain, ungrooved, running face. <IMAGE>

Description

SPECIFICATION Skis This invention relates to skis.

The invention is particularly, though not exclusively, concerned with skis for use on artificial ski-slopes and with the soling of such skis.

Conventional skis, which for example are soled with polyethylene, are reported to have a coefficient of friction on snow of approximately 0.05. The coefficient increases substantially, for example to a value of 0.135, when such skis are used on artificial ski-slopes surfaced conventionally with fibre matting, with the consequence that:: (a) it becomes necessary to adopt angles of slope inclination of at least 100 to 120, thereby limiting choice of site and deterring the inexperienced skier; (b) even when inclined at an angle of as much as 120 the slope can be 'slow', particularly when dry, to an extent that significantly limits possible enjoyment for the skier; (c) the soles, in particular those of polyethylene, of the conventional skis used, wear rapidly and have a shortened life, perhaps of as little as 25 hours; (d) the skis may become hot during use leading possibly to delamination of the ski and other damage.

Research and development efforts by others have been directed towards improving the durability and overall characteristics of the fibre material used for artificial ski-slopes and the possibility of lubricating the slope surface to reduce friction and, thereby, the disadvantages identified above. The present invention, in contrast, is directed towards overcoming, or at least reducing, those disadvantages by improvement of the skis used.

According to the present invention, a ski has a sole composed wholly or in part of nylon.

The nylon is preferably filled with a material that contributes lubricative property thereto, and in this respect may be molybdenum disulphide or graphite.

Nylon filled with molybdenum disulphide has been found to exhibit especially advantageous characteristics as a soling material for skis. In particular this material has been found to have good wear-characteristics and a surprisingly low coefficient of dynamic friction as compared with other materials tested, on artificial ski slopes.

Moreover the 'speeds' achieved on artificial skislopes with skis soled with this material have been found to be very significantly improved as compared with those for conventionally-soled skis.

Two constructions of ski in accordance with the present invention will now be described, by way of example, with reference to the accompanying drawing, in which: Figure 1 is a cross-section taken mid-way along the length of a first of the two skis; and Figure 2 is a corresponding cross-section of the second ski.

Referring to Figure 1, the first form of ski to be described has a core 1 of laminated wood sandwiched between a layer 2 of aluminium on its upper surface and a layer 3 of glass fibre. The aluminium layer 2 is faced with a layer 4 of phenolic resin, whereas the sole of the ski is provided on the glass-fibre layer 3 by a layer 5 that is backed by an aluminium layer 6. The sole is edged along both sides of the ski by steel or other metal strips 7.

To the extent that the ski of Figure 1 has so far been described it is of conventional construction, the layer 5 being in such case of high-density polyethylene and having a centrally-located groove that extends the length of the running face of the ski. In contrast to this however, the layer 5 of the present ski is composed of nylon filled with molybdenum disulphide and has a plain, ungrooved running face.

The ski of Figure 2 has the same general construction as that of Figure 1, involving a laminated-wood core 11 sandwiched between an upper aluminium layer 12 and a lower glass-fibre layer 13. The upper aluminium layer 12 is also faced with a layer 1 4 of phenolic resin, but the lower layer 1 3 is soled in this case with a single plain-face layer 15 of nylon filled with molybdenum disulphide, which extends the full width of the ski without edging.

The layers 5 and 15, which are bonded by epoxy resin to the layers 6 and 13 respectively, are formed by strips of the material, being nylon filled with molybdenum disulphide, sold as "GS" under the trade mark NYLATRON by Polypenco Limited. This material was selected from a range of fourteen materials, as follows:: A. high-density polyethylene-conventional ski sole; B. polyethylene having an ultra-high molecular weight; C. virgin polytetrafluorethylene (p.t.f.e); D. p.t.f.e. filled with mica, as sold under trade mark FLUOROSINT; E. p.t.f.e. filled with graphite; F. p.t.f.e. filled with graphite and bronze, as sold under trademark DQ1; G. p.t.f.e. filled with glass fibre; H. p.t.f.e. filled with glass powder; I. p.t.f.e. filled with ceramic, as sold under trade mark RULON; J. p.t.f.e. filled as sold under trade mark SHAM BANG; K. glass cloth coated with p.t.f.e.; L. acetal as sold under trade mark KEMETAL; M. mica laminate as sold under trade mark FORMICA; X. nylon filled with molybdenum disulphide as sold as "GS" under trade mark NYLATRON.

A preliminary selection from the fourteen was made of materials A, B, C, E, L, M and X on. the basis of low friction, wear resistance and elasticity. The lowest value of the coefficient of static friction on the artificial ski-slope surface, namely of 0.083, was exhibited by material C. The next lowest values, 0.1 17 to 0.122, of the coefficient were exhibited by materials B, E, L and A, in that order, with the value for material X being some 0.124, and that for material M some 0.132. Surprisingly, however, material X was found to have the lowest coefficient of dynamic friction on the artificial slope, its value being 0.1 1 5"the order of preference as between the seven materials in respect of dynamic friction being X; L; A (with a value of 0.135); C; E; B; and M (with a value of 0.139).

Material X, like unfilled nylon, known to have a high absorption of water (0.8 to 1.4% by weight within 24 hours), was expected in consequence to exhibit dimensional changes in conditions of varying moisture that would make it unsuitable and result in ski-distortion; the dimensional changes that have been experienced in practice are slight and are readily accommodated within the flexibility of the ski. Furthermore, it has been found that material X, of all the materials tested having an acceptable fiexibility, has the best wear resistance on artificial ski-slopes.

With pairs of skis soled with nylon filled with molybdenum disulphide, and constructed as described with reference to Figures 1 and 2, significantly increased speeds (for example increases in excess of 10%) down artificial skislopes have been achieved as compared with those obtained using conventional skis. Less wear than with conventional skis has been found also.

Omission of metal edging as illustrated in Figure 2 reduces cost and wear of the artificial ski-slope material, but tends to make change of direction more difficult.

It is believed that the most advantageous proportion of molybdenum-disulphide filling in the nylon material is about 5% by weight. However amounts up to about 7% by weight are believed to yield worthwhile results.

Although the invention has been presented above more especially in the context of use of nylon filled with molybdenum disulphide, nylon unfilled, or filled with other material that contributes lubricative property (as compared with unfilled nylon), may be utilised. More particularly, nylon filled with graphite may with advantage be used instead. It is possible, especially with the latter material, that improvements the same or similar to those achieved on artificial ski-slopes, might by realised on other surfaces, for example, on snow.

Claims (9)

Claims

1. A ski having a sole composed wholly or in part of nylon.

2. A ski according to Claim 1 wherein the nylon is filled with a material to contribute lubricative property thereto.

3. A ski having a sole compose wholly or in part of nylon filled with molybdenum disuiphide.

4. A ski according to Claim 3 wherein the amount of molybdenum disulphide in the nylon lies within the range up to about 7% by weight.

5. A ski according to Claim 3 wherein the amount of molybdenum disuiphide in the nylon is about 5% by weight.

6. A ski having a sole composed wholly or in part of nylon filled with graphite.

7. A ski according to any one of the preceding claims wherein the sole has a plain, ungrooved, running face.

8. A ski substantially as hereinbefore described with reference to Figure 1 of the accompanying drawing.

9. A ski substantially as hereinbefore described with reference to Figure 2 of the accompanying drawing.