generally to do with getting the pressure correct on all the door sets
so
that the door, when closed, sucks in to the bodyside and is held
there, so
that the door interlock (central door locking) can be activated by the

driver or guard to secure the train.

I think I'm missing the problem here. Why can't the doors just have
more
than enough pressure to close them, then theres no problem whether the
train is flexing, banking or upside down. Why do they have to have the
exact amount?

B2003