Abstract:
A heel piece of a safety binding for a ski boot, comprising a sole grip body ( 7 ) which is mounted on a stirrup piece ( 4, 5 ) articulated to a plate ( 3 ) which is in turn mounted so as to pivot on a base ( 2 ) mounted and immobilized on a rail ( 1 ) which is fixed to the ski. The heel piece is equipped with a ski brake ( 8 ) which is mounted on the base ( 2 ), in front of the pivoting plate ( 3 ) so that it moves with the base and remains at a fixed distance from the pivot axis.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a heel piece of a safety binding for a ski boot, comprising a sole grip body which is mounted on a stirrup piece articulated to a plate which is in turn mounted so as to pivot on a base mounted and immobilized on a rail which is fixed to the ski. 
     PRIOR ART 
     A heel piece of this type has been marketed by the applicant under the brand LOOK  37 . Apart from the way in which the base is mounted on a rail, this heel piece is produced as described in patent CH 397 500. 
     This heel piece is intended to interact with a front binding, or toe piece, associated with a ski brake which can be raised by the pressure exerted by the boot on a pedal articulated to the arms of the brake. The position of the brake close to the front toe piece is unfavourable, because it tends to hinder insertion of the front end of the boot, in particular the sole, under the jaw of the front toe piece. It would therefore be preferable to arrange the brake close to the heel piece, as is the case in other types of bindings. 
     It would furthermore be appropriate for the position of the brake relative to the position of the pivoting plate not to vary as the base is moved on the rail, for adjusting the length of the binding. 
     SUMMARY OF THE INVENTION 
     To this end, the heel piece according to the invention is one which is equipped with a ski brake arranged in front of the pivoting plate, this brake being mounted on the base and articulated about an articulation axis that is transverse relative to the base and can be raised by the pressure exerted by the boot. 
     The distance between the pivot axis of the pivoting plate and the articulation axis of the brake is furthermore less than 70 mm, and preferably less than 20 mm, so that the brake is always actuated by the pressure of the heel region of the boot. This is desirable not only because of the optimum pressure exerted by the boot, but also because of the fact that the lower face of the sole of the boot, in front of the heel, often does not have enough area to actuate the pedal of the brake. 
     In the heel piece according to the prior art, the diameter of the pivot of the pivoting plate is such that the maximum distance of 70 mm cannot be adhered to. In order to achieve this maximum distance, it is possible to reduce the diameter of the pivot, but the forces on the latter and the play in the vertical planes increase rapidly as the diameter of the pivot decreases. Controlling these parameters properly leads to extra cost. 
     In order to solve this problem, in a preferred embodiment of the invention, the plate is pivotably mounted on the base through the mutual engagement and interaction of at least one rib in the form of an arc of a circle in a cutout in the form of an arc of a circle, these circle arcs being located between the pivot axis of the plate and the rear of the base. 
     According to a particular embodiment of the invention, the cutout in the form of an arc of a circle is formed in the pivoting plate, and the base has at least two concentric ribs interacting with each of the sides, in the form of an arc of a circle, respectively of the cutout. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The appended drawing represents an embodiment of the heel piece according to the invention by way of example. 
     FIG. 1 represents a view in axial section thereof on a vertical plane. 
     FIG. 2 is an exploded view of FIG.  1 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The heel piece which is represented essentially comprises a rail  1  which is intended to be fixed to a ski by means of screws, a base  2  which is made of molded synthetic material and is mounted on the rail  1  in such a way that it can slide longitudinally in order for its position to be adjusted, a plate  3  which is mounted so as to pivot on the base  2  and is provided with two parallel cheeks  3   a ,  3   b  to which a pair of parallel arms  4 ,  5  are articulated, a cam (not shown) extending between the upper ends of these arms and passing through the transverse bore  6  of a tubular binding body  7  which at the same time forms a heel grip, as represented and described in patent CH 397 500 and as is well known for this type of binding, an example of which is the LOOK  37  binding, and the brake  8  articulated to the front end of the base  2 . 
     At the rear, the base  2  has an extra thickness  9  in which a housing  10  is formed. This housing  10  accommodates a cylindrical body  11  which has a helicoid rib  12  that interacts with a row of oblique grooves  13  formed in the rail  1 . The cylindrical body  11  is pushed against the rear of the housing  10  by a spring  14 , and can be rotated by a screw slot  15 . These setting means are known per se and will not therefore be described in further detail. 
     In order for it to be pivoted, the plate  3  has a cutout  16  having two edges in the form of concentric circle arcs which determine the geometrical axis by which the plate  3  pivots and are located between this pivot axis and the rear  9  of the base  2 . This cutout  16  interacts with ribs  17  and  18 , in the form of arcs of circles, which are formed on the upper face of the base  2  on which the plate  3  rests. These ribs also determine the amplitude through which the plate  3  pivots. The pivoting plate  3  is held vertically on the base  2  by a small plate  19  which has a tab  19   a  cutout and bent through a right angle downward. This tab  19   a  has two holes  19   b , in which two hooks  20   a  engage which are cutout and raised in a mating plate  20  placed under the base  2 . The plates  19  and  20  are connected by a rivet  21  passing through the plate  3  and the base  2 . The upper plate  19  is covered by a mask  22 . 
     The plate  3  also has, in front of the cutout  16 , two lugs  23  and  24  which are directed downward and pass through the base  2  via a slot  25  in the form of an arc of a circle centered on the pivot axis a of the plate  3 . The ends of a torsion spring  26  which is mounted about a stud  27  linked to the base  2  bear on these lugs. The effect of the spring  26  is to bring the pivoting plate  3  into a central position after the binding has been released, through its action on the lugs  23 ,  24 . 
     Toward the front, the base  2  has two front abutment faces  27 , above which two arms  29  parallel to the longitudinal axis of the base and of the rail extend. The intermediate parts  8   a  of the brake arms  8  bear against these faces  27 , these intermediate parts constituting the pivot axis of the brake which has two branches  30  and  31 . These intermediate parts  8 a are held at the top by the arms  28  and  29  of the base. The parts  8   a  define a geometrical pivot axis b (FIG.  1 ). The upper ends  8   b , bent through a right angle, of the brake  8  are articulated in a brake pedal formed by an upper plate  32  and a lower plate  33  fixed to the plate  32  and trapping the ends  8   b  of the brake. The rear end of the plate  33  has a bent fork  34  which holds a pin  35  and allows passage for the end of a rod  36  which is articulated to the pedal  32  by the pin  35  and whose other end is articulated by means of a pin  37  to an auxiliary part  38  which is made of stamped metal and is fixed by rivets to the arms  28  and  29  of the base  2 , under these arms and between these arms. The bar  37  is mounted in two yokes  39  formed on the plate  38 , so that the bar  37  is essentially level with the upper face of the arms  28  and  29 . Around the bar  37 , on each side of the rod  36 , two helical torsion springs  40  and  41  are mounted, the ends of which bear respectively on the part  38  and on the rod  36  so as to keep the rod  36  in the raised position represented in FIG. 1, that is to say to keep the brake arms  30  and  31  in a lowered braking position. 
     The articulations of the brake  8  and of the rod  36  are therefore linked to the base and therefore move with the base as the latter moves on the rail  1 . 
     The creation of the pivot means by the inter-action of the cutout  16  and the ribs  17  and  18  has made it possible to bring the articulation axis b of the brake substantially close to the pivot axis a of the plate  3 , at a distance x, while keeping a pivot (the ribs  17  and  18 ) of relatively large diameter and therefore ensuring good stability for the pivoting plate  3 . This distance x can readily be less than 70 mm, which in all cases ensures that the pedal  32  is operated properly by the heel of the boot. The distance x may even be reduced to a value of less than 20 mm. As for the axis by which the pedal  32  is articulated to the base, which axis is formed by the pin  37 , it may be very close to, or even secant with the pivot axis a of the plate  3 . 
     On the basis of the mounting principle according to the invention, a number of alternative embodiments are possible. In particular, the cutout could be formed in the base  2  and the ribs could be formed on the plate  3 . The cutout could be a simple hollowing. 
     The ribs could be replaced by a single rib of varying width. 
     In known fashion, the brake could be without a pedal. In this case, the axis b could be brought yet closer to the axis a.