I made some more modifications. First how the design of lego is:
And this what I made, to prevend that the connecting rods blocks the bog wheels:
I changed the connecting rods also, otherwise it will be still wider than 8studs. Trains wider than 8 studs means collisions between other trains. Tracks lay next to eachother with 12v. I adjusted the 1/2pins of technic lego:
This means the emerald train is now exactly 8studs wide:
Here again the bottom view with arrived parts today:
Here a pic of the train itself, which almost look like the orginal design. Only modified for 12v.


colours
