Wyrleybart
Established Member
Don't know much about the Mk5 sets but I am getting the impression they have been created as a poor man's "shove" fixed set. They seem to use the two pipe air brake system with normal brake propagation from the leading driving cab. It can be assumed that a sixth vehicle in the formation would have no negative results, but would actually improve braking capabilies even if brake release might be seconds slower.One criticism that has been levelled at the Mark 5A stock (as opposed to the Mark 5 stock used by the Caledonian Sleepers) is the lack of flexibility.
Unlike the Caledonian Mark 5s, the 5As are a fixed formation- basically an unpowered unit onto which can be coupled an electric or diesel loco.
I’m informed that one cannot produce a ten car set by sandwiching a loco between two sets of coaches with DVTs at both ends, but I do wonder whether would it be possible to create a ten car train in some other way with these when needed, perhaps coupled DVT to DVT and with the locos top and tailed?
Or alternatively coupling two sets together one after the other (ie “68 - trailers - DVT - 68 - trailers - DVT” or vice versa)?
Does anyone know for sure?
Seems a tad inflexible if not, given the 168 units with their 2, 3 and 4 car formations can be coupled together in multiple in more or less any permutation from 2-10 cars!
The issue is obviously the TCMS or whatever it is known as on CAF built trains. As the rakes are semi permanently coupled it would be easy to assume that Once some of the rakes could be lengthened to six cars then the TCMS would need "one off" updates to the 6 vehicles. It must be feasible but clearly DfT don't want to pay the price.