Land vehicles – Skates – Runner type
Reexamination Certificate
1999-01-27
2001-07-10
Mar, Michael (Department: 3611)
Land vehicles
Skates
Runner type
C280S617000
Reexamination Certificate
active
06257612
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a gliding board, in particular for gliding on snow, for the practice of skiing or the like. It may be an alpine ski or a cross-country ski.
BACKGROUND OF THE INVENTION
Gliding boards having a raised platform which is intended to accommodate the toe piece and the heel piece of the safety binding on its upper part are already known. This platform rests on the gliding board over its entire length in the support region (see for example documents FR 2 649 902 corresponding to U.S. Pat. No. 5,135,250 and FR 2 675 390 corresponding to U.S. Pat. No. 5,393,086).
The Applicant's document FR 2 734 489 described a monolithic raised platform whose front and rear ends overhang and do not rest on the board.
These skis with a raised platform whose ends overhang have, on the one hand, the advantage of raising the skier's feet relative to the ski board and thereby increase the angle at which the edge can be set before the foot slips and, on the other hand, make it possible to unclamp the ski, which keeps the intrinsic mechanical properties of the board, without affecting the rigidity of the boot. Further, the thrusting force of the heel piece has no effect on the curvature of the ski. This provides a uniform assembly which does not substantially rigidify the ski flexurally.
SUMMARY OF THE INVENTION
The object of the invention is to improve this type of gliding board with a raised platform whose ends overhang.
According to the invention, the gliding board, of the type having a raised platform which is intended to accommodate the toe piece and the heel piece of a safety binding on its upper part and which rests on the board via its central part, said platform having its front and rear ends overhanging and not resting on the board, is one wherein said platform has a torsional stiffness such that the maximum angular deformation of a free end under the effect of a twisting moment of four newton meters (4 N.m) exerted at four hundred and sixty millimeters (460 mm) from an engagement zone is less than one and a half degrees (1.5°).
This torsional stiffness feature is useful for allowing better accuracy when executing turns, which is necessary for the practice of slalom.
Advantageously, in practice, the platform has a tubular structure over the essential part of its length and at least over part of its cross section.
The use of a tubular structure over the essential part of its length and at least over part of its cross section makes it possible to optimize the weight/stiffness ratio, that is to say to obtain a hollow structure which is torsionally stiff for minimal weight. For example, for a cylindrical hollow tube having an internal diameter equal to one half of the external diameter, compared with a solid tube having the same diameter, the angle of twist and the maximum strain are increased by approximately six per cent (6%), while the reduction in weight is as much as twenty-five per cent (25%).
The combination of these two characteristics makes it possible to obtain a ski having a high degree of accuracy, while having minimal weight, which is therefore well-suited to competition.
Advantageously, in practice:
the platform has a linear density of less than 800 grams per meter of length, preferably close to 700 grams per meter of length; this is because it has been observed that, if the weight exceeds 800 grams, this impairs the quality of skiing;
the platform has a plurality of tubular structures parallel to its longitudinal axis;
the platform centrally has an inverted-U profile; the parallel branches of the U then have a tubular structure and bear on the gliding board; in a variant, at least the portion connecting the branches of the inverted-U includes tubular structures over its entire length;
the platform is made of light metal, for example aluminum or other metal alloys, or of composite structure: textile/plastic;
the platform is made of a composite and the longitudinal hollow structure is filled with an expanded foam;
the ratio between the length of contact (A) of the platform with the board (or lower part) and the length (L) of said platform (or upper part) satisfies the formula:
0.25<A/L<0.75
with L between 450 and 600 mm, in order to accommodate standard lengths of safety bindings and boot sizes.
It has been observed that, if this ratio A/L is less than 0.25, the platform then overhangs too much, which compromises the torsional and flexural stiffnesses of the assembly; however, if this ratio exceeds 0.75, the assembly is flexurally too rigid.
Likewise, the height H by which the platform is raised relative to the top of the ski should advantageously be between 10 and 60 mm.
REFERENCES:
patent: 3797844 (1974-03-01), Smolka et al.
patent: 3802714 (1974-04-01), Freegard
patent: 3852896 (1974-12-01), Pyzel et al.
patent: 5397150 (1995-03-01), Commier et al.
patent: 5474321 (1995-12-01), Pritz
patent: 5671939 (1997-09-01), Pineau
patent: 5779258 (1998-07-01), Luitz et al.
patent: 5871223 (1999-02-01), Zanco
patent: 5944336 (1999-08-01), Fagot
patent: 43 17 675 A1 (1993-05-01), None
patent: 195 42 055 A1 (1995-11-01), None
patent: 0 744 196 A1 (1996-05-01), None
Redor Denis
Vailli Johan
Zanco Alain
Mar Michael
Skis Rossignol S.A.
Wall Marjama & Bilinski
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