Ski with gripping device
The present invention concerns a ski, more particularly a cross-country ski, provided with a gripping device fixed in a longitudinal slot located in the sole and body of the ski. 
     Skis equipped with gripping devices such as sealskins or imitations thereof in synthetic materials applied to the soles of the skis are already known. The application of natural or synthetic skins has the disadvantage of imperfect adherence. Moreover, when removing the adhered skin, a part of the adhesive material may remain on the ski sole, thus preventing good sliding. In order to overcome this latter disadvantage, the sticking of strips of gripping skin in longitudinal grooves has already been suggested. This gives rise to another disadvantage, viz. the sole no longer provides a sufficiently large, smooth surface after the adhesive skin has been removed. 
     In addition, the fixing of permanent and undetachable gripping devices to ski soles is also known. These devices cause excessive resistance during downhill skiing. 
     The object of the present invention is to overcome these disadvantages and to make available to skiers a ski equipped with an efficient gripping device which can be easily transformed so as to rapidly obtain a ski having a perfectly smooth sole for downhill skiing, and which may be waxed. 
     In order to achieve this object, the ski according to the invention comprises a substantially U-shaped element undetachably fixed in this slot and a parallelipipedic element detachably fixed in the aperture of the U-shaped element and offering one smooth, longitudinal surface and a brush or other retention system on the other longitudinal surface, the whole in such a way that the detachable element can be fixed either with its smooth surface flush with the sole of the ski or in the inverse position in which the brush protrudes beyond the sole of the ski. 
     It is advantageous to provide a longitudinal groove located in each of the inner walls of the U-shaped element, and a longitudinal projection located on each lateral wall of the detachable element and fitting into the longitudinal groove, in order to retain the detachable element by friction. 
    
    
     The attached drawing shows a cross-section of a special embodiment of the ski according to the invention. 
    
    
     The ski illustrated comprises a body 1 in wood or in a synthetic material reinforced with fiberglass, a sole 2 in polyethylene or in polytetrafluorethylene and a central groove 3 of the known type indicating a longitudinal symmetrical axis (the right hand part of the cross-section is not shown). 
     A longitudinal slot 4 is provided in the sole 2 and the body 1. A U-shaped element 5 which may consist of a known synthetic material is fixed in this slot. In each of its inner walls 6a and 6b a longitudinal groove 7a and 7b, respectively, is provided. 
     A substantially parallelipipedic element 8 having a longitudinal projection 9a and 9b, respectively, on its lateral walls is detachably fixed in the element 5. The element 8 is provided with one smooth, longitudinal surface 10 and its other longitudinal surface 11 is equipped with a brush 12. The width of the brush 12 is limited by two parts of the longitudinal walls 13a and 13b, respectively, having a certain flexibility. The brush 12 may consist of long-piled plush of the &#34;Mohair&#34; variety or another type of retention sole. 
     In order to remove the element 8, it is slid longitudinally until one tip protrudes beyond one extremity of the ski, whereupon the parts 13a and 13b are lightly squeezed. At this point it is possible to disengage the projections 9a and 9b from the grooves 7a and 7b, respectively. If the ski is to be prepared for downhill skiing, the element 8 is inverted by squeezing the parts 13a and 13b and by sliding the projections 9a and 9b into the grooves 7a and 7b respectively. Thus the smooth surface 10 will be flush with the sole 2. The exterior part of the brush 12 will then be located within the empty space 14. 
     Obviously, it would be possible to have several longitudinal projections with corresponding grooves in the place of a single projection 9 with a single corresponding groove 7.