Free-wheel device having clamping cams

In a free-wheel drive, an external cylindrical slideway and an internal cylindrical slideway mounted substantially concentric one to another for relative rotation and defining therebetween a substantially cylindrical gap;

• a series of tiltable clamping cam elements disposed between said slideways within said cylindrical gap, said cam elements being tiltable in one direction into clamping engagement with both of said slideways and tiltable in an opposite direction to tend to disengage said cam elements from said slideways, each cam element comprising an external sliding surface and an internal sliding surface capable of coming into sliding or clamping contact with said respective external and internal cylindrical slideways depending upon the inclination of the corresponding cam element, each cam element further comprising a rearface and a front face, said front face having means defining a convex contact zone;
• a strap spring means of generally cylindrical shape mounted between said slideways and having a plurality of windows adapted for mounting therein said cam elements, one edge portion of each said windows engaging said rearface of the cam element mounted in the corresponding window for defining a pivoting edge for said cam element, said strap spring means being formed with a plurality of pivoting tongues respectively extending from a line of articulation into each of said windows for exerting a force against said convex contact zone of said respective cam elements in such a way that the cam elements are caused to pivot into clamping engagement with the slideways and are pushed towards the pivoting edge of the corresponding window;
• the position and shape of said convex contact zone being such that a lever arm of said force relative to said pivoting edge varies in inverse proportion to the value of said force when the inclination of the cam element varies due to variations of said cylindrical gap.

A clamping cam element structure adapted to be mounted between a pair of concentric slideways defining therebetween a cylindrical gap, said cam element being adapted to be tilted in one direction into clamping engagement with both of said slideways and in an opposite direction to tend to be disengaged from said slideways, said cam element comprising an external sliding surface and an internal sliding surface capable of coming into sliding or clamping contact with said respective cylindrical slideways depending upon its inclination, a rearface and a front face, said front face having means defining a convex contact zone;

• said convex contact zone being adapted for engaging with a pivoting tongue extending from a line of articulation on a strap spring means of generally cylindrical shape mounted between said slideways and having a plurality of windows adapted for mounting therein a plurality of said cam elements, one edge portion of each said windows engaging said rearface of the cam element mounted in the corresponding window for defining a pivoting edge for said cam element, the position and shape of said convex contact zone being such that the lever arm of a force exerted by said pivoting tongue against said convex contact position relative to said pivoting edge varies in inverse proportion to the value of said force when the inclination of the cam element varies due to variations of said cylindrical gap.