Articulated linkage assembly for a surge brake

In a surge brake system for a tractor-trailer combination, wherein the brake unit includes a brake drum and an articulated brake shoe carried on a lever plate for movement into braking engagement with the brake drum in response to the action of forward inertia of the trailer relative to the tractor and out of braking engagement in response to at least one of neutral or rearward inertia of the trailer relative to the tractor, an articulated linkage assembly, comprising:

• (a) a gusset plate substantially adjacent the lever plate land overlying the brake shoe;
• (b) the lever plate having a centrally located and substantially kidney-shaped aperture, said lever plate including a fulcrum end portion;
• (c) a first pin extended from said gusset plate through said kidney-shaped aperture for limiting the movement of said gusset plate relative to said lever plate;
• (d) said gusset plate having a first pear-shaped aperture displaced from said first pin toward the fulcrum end of the lever plate;
• (e) a spring for urging the brake shoe into a rest position, said spring having one end attached to said first pin and the opposite end thereof attached to the lever plate through said first pear-shaped aperture;
• (f) said lever arm having a second pear-shaped aperture reversed relative to said first pear-shaped aperture and displaced substantially along the same arc of curvature of said first pin and inwardly of said first pear-shaped aperture;
• and
• (g) a second pin attached to said gusset plate and extended through said second pear-shaped aperture wherein a limited movement of said pins in associated ones of said apertures on movement of the trailer from a condition of forward inertia to a condition of rearward inertia, limits the movement of said brake shoe to a non-braking contact position concurrently with the action of said yieldable means to urge the brake shoe to said rest position.