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) )/1000.
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)