I believe that you need to use a typical train model that considers every car as a body with one longitudinal d.o.f. In UM we use UM Train module for that. I think you do not need detailed (part by part) simulation of couples/draft gears. You may consider the model more generally as a force function with given slacks and deflection-force diagram.

UM Train is briefly described on our web site here:

http://www.universalmechanism.com/en/pl ... x.php?id=3Here is the UM Train user's manual:

http://www.universalmechanism.com/downl ... _train.pdf.

Slacks in draft gears and its force diagram influence on the longitudinal train dynamics. It is true. We recently publish a paper where we considered longitudinal train dynamics including slacks in draft gears and its experimental force diagrams. That paper is presented here:

http://www.universalmechanism.com/en/ne ... php?id=123. There is a link to download the full paper. If 50 free downloads is already exhausted, just let me know and I will share it with you.