This is a start on a trailer to be fitted to 42078 Mack truck. 
I have decided to use two axles. These are mounted on a two stage pivot so that the trailer can adapt to rough terrain. 
However, to stay horizontally, it depends on a stiff connection to the tractor truck. 
The lenght has been set to four times 13L beams. This forms the base.

First add-on is a trough that will become a tipper trailer (cf. my folder on 8872 compatible). 

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