title: D-value (transport)
text: # D-value (transport)
  
  In transport, D-value is a rating in kN that is typically attributed to mechanical couplings, and reflects dynamic loading limits between a towing vehicle and a trailer.
  
  The corresponding formula for a truck and trailer combination, used to determine the required D-value of a coupling, is:
  
  T = Weight of towing vehicle including the vertical load on the fifth wheel R = Total weight of the loaded semi-trailer U = Vertical load on the fifth wheel g = Acceleration due to gravity (assumed to be 9.81 m/s 2 )
  
  D (kN) = g x ((0.6 x T x R)/(T + R - U))
  
  