DMUs were intended to haul conventional carriages, and sometimes did (more often vans but also passenger carriages). It was one of the reasons why dmus had vacuum brakes while emus had more effective air brakes. The mu engine controls connection didn't go through to hauled vehicles at the back but the vacuum brakes did. So they could be hauled, without engine running, by a loco in mixed formations.
Summer trains without heating were standard, whether the loco could provide it or not. Lighting was always by batteries recharged by axle-driven generators on each vehicle, so these would also work as normal, provided they were switched on before starting, which was normal in the old days anyway - again except for emus, which commonly had central guard control.
The whole concept of "scratch sets" was not really one employed a generation ago and before, when formations were put together as required. Many services, of course, had a standard and documented formation, but remarshalling during the day was common, even such issues as a late rush of passengers and the loco would go off for a couple of extra coaches.
Vacuum brake was no bar to 100mph operation - this had taken place from the start of electric working in 1960, when air brake didn't even come along until 1967. The restriction was only on B1 bogied vehicles; Commonwealth and B4 were for full speed, and most of the post-1959 Mk 1 build had these. So did the BG vans, but not the GUVs and lesser ones. However, there were no air braked Mk 1 passenger vehicles, and even the first build of Mk 2 were the same.
Given that signal spacings and associated speed restrictions were put in place for vacuum stock, when better air braking came along that provided a much greater margin.
Last edited:
