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Trailer Hitch Ball Coupler Size Equations and Calculators

Power Transmission Design and Engineering
Engineering and Design Applications

Trailer Hitch Ball Coupler Size Equations and Calculators.

The required trailer coupling size is determined by the D value.

The formula for the D value is as follows:

D = ( G · T · R ) / ( T + R )

Where:

D = D value, in kN,
T = Permissible gross weight of the towing vehicle, in t (Metric Tons),
R = Permissible gross weight of the trailer, in t (Metric Tons),
t = Metric tons,
G = 9.81 m/s²

Example:
Vehicle T31, 19.464 FLC
Permissible gross weight 18000 kg = T = 18 t
Trailer load 22000 kg = R = 22 t

D value:

D = ( 9.81 · 18 · 22 ) / ( 18 + 22 )

D = 97 kN

If the trailer gross weight R and the D value of the coupling device are specified, the permissible gross weight of the towing vehicle T can be determined using the following formula:

T = ( R · D ) / ( ( 9.81 · R ) - D )

If the permissible gross weight of the towing vehicle T and the D value of the coupling device are specified, the maximum permissible trailer load R can be determined using the following formula:

R = ( T · D ) / ( ( 9.81 · R ) - D )