This SAE Standard applies to upper coupler kingpins for commercial trailers and semitrailers in the unladen condition. See Figure 1. A 90 degree ± 1 degree angle extends (in all directions) from the centerline of the kingpin to the upper coupler plate surface within a 48.26 cm (19 in) radius. The upper coupler plate surface should not bow downward (convex) more than 0.635 cm (1/4 in) within a 48.26 cm (19 in) radius or more than 0.3175 cm (1/8 in) at a radius of 25.4 cm (10 in) from the kingpin. The upper coupler plate surface should not bow upward (concave) more than 0.15875 cm (1/16 in) within a 48.26 cm (19 in) radius. (See Figure 2.)
SAE J700-2001 history
2020SAE J700-2020 Upper Coupler Kingpin - Commercial Trailers and Semitrailers
2011SAE J700-2011 Upper Coupler Kingpin Commercial Trailers and Semitrailers
2001SAE J700-2001 Upper Coupler Kingpin—Commercial Trailers and Semitrailers
1993SAE J700-1993 Upper Coupler Kingpin - Commercial Trailers and Semitrailers
1985SAE J700-1985 Upper Coupler Kingpin - Commercial Trailers and Semitrailers
1970SAE J700B-1970 FIFTH WHEEL KINGPIN—COMMERCIAL TRAILERS AND SEMITRAILERS