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Calculating D-Value

by | Apr 22, 2017 | Technical Guides | 6 comments

D -Value for Pintle Hooks

D -Value for pintle hooks has long been a mystery for many when selecting the right size for a truck.

“So I think I need a 10t pintle hook because I am towing an 8t trailer with a 20t truck.” The manufacturer states he does not have a D-Value. (in this case, you cannot use this pintle hook with no D-Value)

  • D-Value is the maximum horizontal load in kN given to a pintle hook.
  • D -Value for Pintle Hooks is critical when selecting the correct pintle hook because depending on your truck and trailer weight, the D-Value is changing.
  • If D-Value results from dynamic testing, a maximum value is applied to the pintle hook being tested.

In case of a Couplemate 10t pintle hook, the D-Value is 49kN

Review our Min requirements for D Value and select your truck GVM and Trailer ATM.

For an 8t trailer, the max truck GVM is 20t a pintle hook of a Min 56kN is are required.

Our 14.5t Pintle Hook has a D Value of 73kN and can easily tow an 8t trailer. You also may wish to choose a ring coupling to install on your trailer.

Ring couplings fall into the same equation.

What to do if your coupling has No D-Value

If it does not have a maximum D_Value then you cannot calculate the correct towing combination.

This can happen when wrong d_values are selected, or your rig setup is wrong.

Couplemate has tested its 3″ ring coupling to 49kN.

From the table, it is easy to calculate the correct towing configuration.

This article follows our last article on Dee Shackle – How to Select the Correct Size.

The items below require a D-Value


  1. Linton Young

    Hi there I’ve got an Isuzu with a GVM of 10.700 kg and a tri axel plant trailer that can 7000kg and weighs in 2000kg do 9000kg . I won’t be ever putting more than 4500 kg on it so this equates to 6500 kg. What is my D value ?

    • Stephen Wotherspoon

      Hello Linton, The Isuze is 10.7t and the registered trailer is 4.5t = Min 31kN D-Value. If you wish to register to carry more then you are looking at Air Brakes which are very expensive. Of course you can choose a higher D-value is you wish. I am assuming you will have either electric brakes or electric/hydraulic.

      • Linton Young

        Hi Stephen , the trailer has air brakes on 3 axels and can carry 7000 kg. I won’t be carrying that much weight. My combined weight ie load plus trailer will only be 6500 kg . I can legally tow that as long as I have 2000 kg in my truck. I’m looking at a rated towbar but don’t know the D value ( thinking between 41 to 48 ?? . After the bar is sorted then I’m getting air the the trailer. Any help would be appreciated.

  2. Jake Baillie

    I have a UD with 25ton gvm what d value rating do I need to tow 15 ton

    • Stephen Wotherspoon

      Hello Jake, You will need an attachment with a D-Value of not less than 92kN. Thank you for your question. Steve Wotherspoon


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