Calculation D- and V-value

A performance value, 'D-value', is used in order to choose the correct coupling equipment (for centre axle trailer also V-value). The coupling equipment you choose must have higher or at least the same values, D- and V-value, as the calculated vehicle combination.

Use our calculation guide below and the following product pages to make your choice of coupling equipment.

	D-value for towing vehicle and semi-trailer The 'D-value' is defined as the theoretical reference value for the horizontal force between towing vehicle and trailer. It is taken as a basis for testing and used to specify performance of fifth wheel equipment.
T:	Technically permissible maximum mass in tonnes of the towing vehicle
R:	Technically permissible maximum mass in tonnes of the semi-trailer*
U:	Fifth wheel imposed vertical load in tonnes. * Following applies to semi-trailer: R=U + a., which is the total weight of the semi-trailer. It takes into consideration maximum kingpin pressure 'U' on the fixed, slider or height adjustable fifthwheel and 'a' the maximum axle weight of the semi-trailer.

	Dc-value for towing vehicle and centre axle trailer (rigid drawbar) The 'Dc-value' is defined as the theoretical reference value for the horizontal force between towing vehicle and centre axle trailer. It is taken as a basis for testing and used to specify performance of coupling equipment for centre axle trailers.
T:	Technically permissible maximum mass in tonnes of the towing vehicle including the vertical load of the centre axle trailer, S.
C:	Sum of the axle loads of the centre axle trailer carrying maximum permissible load, in tonnes
	When choosing equipment for centre-axle trailers both V- and Dc-value must be observed.

	V-value for towing vehicle and centre axle trailer (rigid drawbar) The 'V-value' is defined as the theoretical reference value for the vertical force between towing vehicle and centre axle trailer. It is taken as a basis for testing and used to specify performance of coupling equipment for centre axle trailers.
X:	Length of the loading area of the trailer, in metres.
L:	The theoretical drawbar length, i.e. the distance between the centre of the drawbar eye and the centre of the axle assembly, in metres.
C:	Sum of the axle loads of the centre axle trailer carrying maximum permissible load, in tonnes.
a:	Vertical acceleration in the coupling point. - For vehicles with air suspension or equivalent: a = 1,8 m/s² - For vehicles with other suspension: a = 2,4 m/s².
	When choosing equipment for centre-axle trailers both V- and Dc-value must be observed.

	Support load for centre-axle trailer (rigid drawbar) The support load S is the part of the centre-axle trailer´s total weight that is transferred to the coupling in static conditions (stationary).
	Axle load with service weight (kg).
	Support load with service weight (kg).
C:	Axle load with total weight (kg).
A:	Distance from drawbar eye centre - Front edge of load area (m).
L:	Distance from drawbar eye centre - Axle centre (m).
X:	Load length (m).
	Support load with max load: Max load: Total weight:

	D-value for towing vehicle and full trailer (hinged drawbar) The 'D-value' is defined as the theoretical reference value for the horizontal force between towing vehicle and trailer. It is taken as a basis for testing and used to specify performance of coupling equipment.
T:	Technically permissible maximum mass in tonnes of the towing vehicle
R:	Technically permissible maximum mass in tonnes of the full trailer