Before revision: The corresponding formula for a truck and trailer combination, used to determine the required D-value of a coupling, is: D (kN) = 9.81 x (Gross Vehicle Mass X Gross Trailer Mass)/(Gross Combination Mass) .
After revision: The corresponding formula for a truck and trailer combination, used to determine the required D-value of a coupling, is: D (kN) = 9(81 x (Gross Vehicle Mass X Gross Trailer Mass)/(Gross Combination Mass) .