Yeah Udo your Kinda right. We call the first Trailer the "lead" then the 2nd is the "A" and the last Is the "Dog" Its all about Axle combos If you look at that Last Cattle truck set up thats a 53mtr std "Quad" and has 7 axle groups we run "Super Quads" which Have 8 Axle groups and 60mtrs Long we also run Quinns (5 trailers) but still only 60mtrs, The weight you can carry is set by the number of axles in a "Group" ours are all 3axle groups but they do 4 axle groups as well and these are called "Mega Quads" and run 225tons loaded.