Ski safety binding

A ski safety binding able to release horizontally and vertically intended to hold in place the end of a boot, comprising:

• a body;
• a grip articulated on this body about a horizontal pin defining an articulation axis;
• a lateral-retention means for retaining said boot;
• elastic return means, for returning the lateral-retention means and the grip to a closed position of the binding, said return means comprising at least one spring acting via at least one piston on a transmission mechanism for performing a rotational and translational movement;
• said spring being set between the piston and the grip and the lateral-retention means;
• wherein said transmission mechanism comprises a first part including a rocking lever rocking in a plane perpendicular to said articulation axis, said rocking lever bearing permanently against the piston and bearing against the grip and the lateral-retention means in such a way that the position of said rocking lever is determined at each instant by first and second forces acting on opposed ends of the rocking lever, said first and second forces corresponding to different releasing directions, and by a third force acting between the first and second forces and in a direction opposed to said first and second forces via the piston;
• and
• wherein on of the rocking levers and the piston have a convex bearing surface positioned such that when the rocking lever is rocking, the bearing zone is moved in one of an upward and downward direction relatively to the piston thereby modifying gradually the lever arms of the forces acting on the rocker ends and wherein the body is mounted pivotally on a vertical pivot and the lateral-retention means comprise at least one fixed stop and wherein all the moving parts of the transmission mechanism are in permanent linear contact with the piston, the grip and the stop respectively and wherein the two moving parts consist of two levers, namely a first lever articulated about an axis parallel to the axis of articulation of the grip and provided with a nose bearing against an incline of the grip and a second moving part articulated in the upper part of the first moving part about an axis parallel to the axis of articulation of the grip, extending downwards and the end of which bears at least indirectly against the stop or stops respectively for returning the body under torsion and wherein the axis of the articulation of the first lever is secant to the axis of pivoting of the body and the lower end of the second lever bears against at least one lever, one arm of which bears against the fixed stop and wherein the rocking lever bears, via a transmission rod, against a first and second lever pivoted about two vertical axes symmetrically on each side of the longitudinal axis of the binding, and one arm of which bears respectively against two fixed stops arranged symmetrically on either side of the said longitudinal axis.