The present invention concerns a cross-country ski, in particular intended for what is known as the "classic" tech- nique, but one that can be used also for what is known as the "skating" technique, in which a skating movement is used.

When skiing, it is important to be able to avoid backwards slipping, independent of the style of skiing. When skiing with the classic style, the lower surface of the ski is waxed or provided with another mechanical arrangement, such as backwards facing notches in the coating on the lower surface of the ski, which notches are intended to grip the ski track and prevent slipping backwards. Mechanical arrangements have always suffered from the disadvantage that they impair the forward glide. Waxing must be repeated often in order to obtain the desired effect, and it must also be adapted to the snow conditions. When using the skating technique, slipping backwards is avoided to a large degree by using a skating movement in combination with waxing. The best conceivable forwards glide is, with few exceptions, desired.

Essentially all skiers experience occasional problems either with skis that slip backwards or with skis that slip back- wards to a lesser degree but that, on the other hand, have poor glide properties.

The skis are waxed, in order to solve the problems with slip ^¬ ping backwards or poor glide. Waxing, however, is a compli- cated procedure that takes time, and must be carried out in a professional manner in order to achieve the best results. Furthermore, waxing must be carried out differently from one occasion to the next depending on snow conditions and temperature. Furthermore, areas with different temperatures or snow conditions may be passed during one and the same skiing ex ^¬ cursion, which leads to the waxing not achieving the intended best result. Waxing or mechanical arrangements are used to obtain the best grip. If the parts to which grip wax is applied make contact with the ski track, the disadvantage of poor glide arises. In order to solve this problem, cross-country skis have a bend upwards, an arch, at the centre of the ski, and the natural give of the ski is exploited such that this part is to be pressed down against the ski track when the skier places load on this section. The grip wax is applied along a section of approximate length 0.5 m at the said upwards arch at the centre of the ski. The principle is that the skier does not press the lower surface of the skis down onto the ski track at the arch when his or her weight is distributed onto both skis. In this condition, there is to remain a very small arch upwards at the location of the wax. The wax then, in the ideal state, lies just above the snow, which makes possible the maximum glide forwards. When the distribution of weight changes, the arch of one ski will disappear and the wax then brakes somewhat against the snow. It is not possible to main ^¬ tain a fully even balance between the skis such that the arch is perfect between the skis [sic, "mellan skidorna" repeated - the "valv" is not "mellan skidorna"?] when skiing downhill, and one ski will, for this reason, in practice exert some braking effect. When the kick is taken for forwards move ^¬ ment, the weight of the skier is redistributed such that one ski takes up the complete weight of the skier. This action, however, gives in principle only 50% grip. The arch of the ski, it must be remembered, is supporting 50% of the skier's weight. However, further grip is obtained through the use of the skier' s inertia, an extra downwards pressure before the body of the skier has time to be displaced upwards. Currently available solutions do not allow the complete grip that is desired to be achieved, i.e. they do not allow full use of the kick provided by the legs without slipping. Complete prevention of slipping backwards can be obtained if the lower surface of the ski is provided along its complete length with what are known as "ski skins" The forward glide, however, becomes as good as non-existent if this is done. Setting ski skins only on that section of the ski that is waxed does not work very well, either, since this part of the ski will occasionally be in contact with the snow during forwards gliding, when it will exert a braking effect, and it will introduce the risk of falling forwards when skiing downhill .

Current cross-country skis must be adapted to the different weights that different skiers have, and adapted to a certain extent also to their style of skiing. This leads to an unnec ^¬ essarily large range of skis, and thus also more expensive skis.

Thus, the problem to solve for the present invention is to achieve a ski that is designed such that it demonstrates during normal load from the skier a retained arch even when the skier has placed his or her complete weight onto the ski, but one that is so designed that, when the load is redistrib ^¬ uted such that it is exerted only by the skier's forward foot pad, the ski is placed into contact with the underlying sur ^¬ face, i.e. the snow.

The US patent document 5,427,400 has previously revealed a cross-country ski that comprises a convexity in the centre of the ski under the skier' s foot in order to facilitate the downwards pressing of the central section of the ski when the ski is placed under load through the skier actively pressing the foot down in order to obtain grip with the ski.

That which even so could not be solved with this prior art design of a ski is to be able to achieve a pre-determined load point at which the ski is pressed down against the sur ^¬ face .

The purpose of the present invention, therefore, is to solve also this problem.

The above-mentioned purpose of the invention is achieved with a ski according to the invention through the ski comprising at the location of the arch a spring-loaded arrangement that extends in the longitudinal direction of the ski, and where an empty space is present between the upper surface of the ski and the lower surface of the spring-loaded arrangement closest to a binding on the ski, and where the spring-loaded arrangement is designed to collapse at a certain load applied from above such that when placed under load by the skier' s foot the spring-loaded arrangement collapses and the central section of the ski is pressed down such that its lower surface is pressed against a surface under the ski, through the ski being divided at the location of the arch such that it comprises in its longitudinal direction a rigid central part and a pliable lower part, where the pliable lower part is arranged such that it separates from the rigid central part when the spring-loaded arrangement collapses, in order to be pressed down against the surface under the ski.

According to a particularly preferred embodiment of the in ^¬ vention, the ski is divided along its longitudinal direction at the location of the arch so that the ski comprises a rigid central part and a pliable lower part, where the pliable part is arranged such that it separates from the rigid central part when the spring-loaded arrangement collapses to be pressed down such that its lower surface is pressed down against the surface under the ski.

According to a further preferred embodiment, the spring- loaded arrangement is provided at its lower surface with a rigid member, extending through or passing and displaceable relative to the rigid central part of the ski, and connected to the pliable lower part.

According to a further preferred embodiment of the invention, the ski is provided at its lower surface under the location of the skier's foot, with an arrangement that prevents back ^¬ wards slipping.

The invention will now be described in more detail in the form of an embodiment, illustrated by that attached, non- limiting drawings, where Figure 1 shows a side view of a central part of a cross-country ski according to the invention showing the skier's foot without load for kick off, Figure 2 shows a side view corresponding to Figure 1 but with the skier' s foot exerting a load onto the ski for kick off, Figure 3 shows an exploded view of the central section of the ski according to the invention with the parts that are significant to the invention separated from each other, Figure 4 shows a cross-section through the ski at A-A in Figure 3, Figure 5 shows a cross-section through the ski at B-B in Figure 3, Figure 6 shows a view similar to that in Figure 1, but of a preferred embodiment in which the spring-loaded arrangement is provided at its lower surface with a rigid member, passing and displaceable relative to the rigid cen ^¬ tral part of the ski, and connected to the pliable lower part. Figure 7 shows a side view corresponding to Figure 6 but with the skier' s foot exerting a load on the ski for kick off, Figure 8 shows a cross-section through the ski at A-A in Figure 6, and Figure 9 shows a cross-section through the ski at B-B in Figure 7.

A cross-country ski 1 according to the invention is at its forward and rear parts designed as a fully conventional cross-country ski, and can therefore there have the various designs that are known, such as, for example, consisting of various known materials. The ski 1 thus comprises a forward section 2 with the tip of the ski, a central section 3 at which the binding of the ski is arranged, and a rear section 4, where the forward and rear sections undergo transition into the central section 3 without joins.

The central section 3 of the ski is significant for the in ^¬ vention. The central section 3 is thickest in the middle, in known manner, and becomes thinner towards its ends, towards the forward 2 and rear 4 sections. The ski at the location of the arch 5, thus in the central section 3, is provided with a spring-loaded arrangement 6 that extends in the longitudinal direction of the ski 1, and where an empty space 8 is located closest to a binding 7 on the ski, between the lower surface of the spring-loaded arrangement 6 and the upper surface of the ski.

The spring-loaded arrangement 6 may be a fibre-reinforced plastic material, in particular a carbon fibre-reinforced plastic material, or a tape of steel, preferably stainless steel. The spring-loaded arrangement 6 when in its inactive position is either straight or provided with a slight arched form, extending in the longitudinal direction of the ski, i.e. such that the spring-loaded arrangement 6 when seen in cross-section at the centre of the ski 1 (as is made clear by Figure 5) lies higher than it does at the sides of the ski. The ski is designed with respect to its thickness and its material properties such that the arch of the ski can support the weight of the skier when the skier stands normally on the ski, even if the skier stands on only one ski. The spring- loaded arrangement 6 is designed with respect to its thick ^¬ ness and its material properties such that, when the skier places load onto the spring-loaded arrangement 6 by pressing with his or her bodyweight onto the forward pad of the foot 9, the spring-loaded arrangement 6 will "snap", and the cen ^¬ tral section of the ski in its entirety will be pressed down against the surface, the underlying ski track 10, as is shown in Figure 2. The spring-loaded arrangement 6 has thus proper- ties that are similar to those of a steel tape measure, which is snapped by its own weight at a certain degree of extent.

According to one preferred embodiment of the cross-country ski according to the invention, which is the one shown in Figures 1-5, the central section 3 is divided from the side such that the central section 3 consists of a pliable lower part 11 and a rigid central part 12. The pliable lower part 11 is integrated into the ski at its forward and rear parts, but it can, when the central part is placed under load, be caused to separate from the rigid central part 12 in order for the lower surface of the ski to be brought into contact with the underlying ski track 10.

The separation of the pliable lower part 11 from the rigid central part 12 can be achieved by a release foil being in ^¬ serted between the layers that form the pliable lower part and the rigid central part, during manufacture of the ski. The spring-loaded arrangement 6 is located centrally under the place at which the user of the ski, the skier, has the forward part of the foot 9 when skiing, and the spring-loaded arrangement 6 is arranged to collapse when placed under load from the forward part of the foot 9 of the skier, such that a part of the spring-loaded arrangement is pressed down into the empty space 8 between the spring-loaded arrangement 6 and the upper surface of the ski 1. The load on the central sec ^¬ tion 3 is in this way increased such that the lower surface of the ski is pressed down against the surface 10, i.e. the ski track.

The pliable lower part 11 of the ski 1 is connected by a rigid member 13 to the spring-loaded arrangement 6, which is mounted on the upper surface of the ski, and where the rigid member 13 is arranged to pass freely through the rigid cen ^¬ tral part 12 of the ski. The rigid member 13 may be, for example, a peg of wood or plastic that passes through a hole in the rigid central part 12 of the ski. Thus, when the spring-loaded arrangement 6 collapses when a certain load is placed on it from above, the rigid member 13 will be dis ^¬ placed downwards through the hole in the rigid central part 12 of the ski, and it will press down the pliable lower part 11 such that it separates from the rigid central part 12 and is pressed down against the surface 10, i.e. the ski track.

According to the particularly preferred embodiment of the invention that is shown in Figures 6-9, the pliable lower part 11 of the ski 1 is connected to the spring-loaded ar- rangement 6 that is mounted on the upper surface of the ski through rigid edge parts 14 that pass outside of the rigid central part 12 of the ski. The rigid central part 12 of the central section 3 of the ski 1 is, as is made clear by Fig ^¬ ures 8 and 9, somewhat more narrow than the rest of the ski, such that the rigid edge parts 14, when placed under load by the skier and when the spring-loaded arrangement 6 collapses, can be displaced downwards onto the outer surface of the rigid central part 12 and can in this way press the pliable lower part 11 down onto the surface 10, i.e. onto the snow in the ski track. As is suggested by Figures 8 and 9, the rigid edge parts 14 may be designed integrated as one piece with the pliable lower part 11, i.e. of the same material, such that they form a unit with the pliable lower part 11. The edge parts 14 in this way form also a seal for the empty space 8 between the spring-loaded arrangement 6 and the upper surface of the rigid central part 12, as also for the further empty space 15 that is formed between the lower surface of the rigid central part 12 and the pliable lower surface 11, when the latter is pressed down against the ski track in order to obtain traction. Thus, snow is in this way prevented from entering the empty spaces 8 and 15 and from preventing the motion of the pliable lower part 11 relative to the rigid central part 12.

It is appropriate that the pliable lower part 11 of the cen ^¬ tral section of the ski have a length of 300 to 750 mm, and a thickness of 2-10 mm. The spring-loaded arrangement 6 is, in order to obtain a suitable height of motion at the pliable lower part of the ski with distance at the front and with distance from approx ^¬ imately the centre and backwards, located at a suitable height above the upper edge of the ski, suitably 2-12 mm, which constitutes the empty space 8 between the spring-loaded arrangement and the ski 1. A point of pivoting 16 is formed at the end of the empty space 8. This point of pivoting 16 may be formed through a plate 17 being arranged at the upper surface of the ski 1, whereby the forward upper edge of the plate 17 constitutes the point of pivoting. Alternatively, the point of pivoting 16 may be formed by the ski being pro ^¬ vided at its upper part with a cavity, which in this case forms also the empty space 8.

It is appropriate that the spring-loaded arrangement be stiffened just before the point of pivoting 16 for the spring-loaded arrangement 6 and at the rear edge of the spring-loaded arrangement 6, such that the rear part of the spring-loaded arrangement 6 is pressed upwards when the for ^¬ ward part is pressed downwards into the empty space 8, and the heel of the skier is in this way compelled to be lifted up. This stiffener 18 may be formed on the upper surface of the spring-loaded arrangement, and is it then arranged to function as a stiffener 18 for the ski boot of the skier. Alternatively, a stiffener may be arranged under the spring- loaded arrangement.

The location of the point of pivoting 16 is to be such that the forward part of a skier's foot, the pad of the skier's foot, is located in front of the point of pivoting 16. When the foot 9 of the skier exerts a load, when the pad of the foot is pressed down and the spring-loaded arrangement 6 snaps, the spring-loaded arrangement 6 will by this action be rotated around the transverse point of pivoting 16, which results in the forward part of the spring-loaded arrangement 6 in front of the point of pivoting 16 being pressed down, while the stiffener 18 of the spring-loaded arrangement 6, behind the point of pivoting 16, is lifted, Figure 2.

It is possible also that the point of pivoting 16 be somewhat displaceable relative to the empty space 8 in the longitudi ^¬ nal direction in order to provide the possibility for adapta ^¬ tion of the snap force that must be applied in order to cause the spring-loaded arrangement 6 to snap. This may be achieved in particular if the point of pivoting 16 is formed from the forward edge of a plate 17 attached to the upper surface of the ski, if the plate 17 is in this case arranged to be dis- placeable in the longitudinal direction of the ski 1.

According to one preferred design, the spring-loaded arrange ^¬ ment may be provided, either above or below itself, with one or several spring-loaded leaves in order to create different forces that are required for the snapping effect.

Even if it is preferred that the spring-loaded arrangement be of carbon fibre or stainless steel, preferably stainless spring steel, it is obvious that also other materials that can be caused to collapse at a given load and subsequently, when the load has been removed, to return to their original form, can be used.

The spring-loaded arrangement 6 may be designed also in dif- ferent versions with different stiffnesses, in order to take into consideration at least one of the weight and power of the skier when he or she kicks off. It is appropriate also that the spring-loaded arrangement be integrated with the binding 7 of the ski such that they form a common unit that is attached to the ski 1.

In order to improve further the ability of a ski 1 according to the invention to grip during kicking off, it is appropriate that the ski is provided also on its lower surface, under at least part of the central section 3, with a material that increases friction or a coating that increases friction, for example a ski skin. Due to the fact that the ski 1 is split and has a pliable lower surface 11 and a rigid central part 12 according to the invention, it is guaranteed that it is principally the lower surface of the central section 3 of the ski 1 that will come into contact with the surface, the ski track, when the skier places load onto the ski such that the spring-loaded arrange ^¬ ment 6 collapses (as is shown in Figure 2 and Figure 7) . On the other hand, through the ski being provided with the spring-loaded arrangement 6 that is caused to collapse, it is in the normal case, when the skier is not placing load onto one foot 9 for kicking off, more rigid than a normal ski, which leads to the lower surface of the central section 3 of the ski not coming into contact at all with the surface, the ski track, and thus not hindering the movement of the skier forwards during, for example, coasting downhill, and it thus in no way brakes the skier such that he or she falls, even if the lower surface of the central section is provided with ski skins or other material that increases friction and prevents sliding backwards.