Post by Tessy
Anyway, we're not here to define what makes a DMU we're here to define what
makes a loco! If you want a definition of a DMU go and do it yourself. Do
I have to do all the hard work around here?
I think you're /making/ all the hard work for everyone else! :-)
OK, now we have to define "locomotive". The dictionary defines it as,
in this instance, a "locomotive engine", "having the power of
movement". In the railway context, it's a Traction Unit - but then, so
are various other things, notably Multiple Unit trains, Self-Propelled
Rail Vehicles and Road/Rail Vehicles Operating in Rail Mode (says the
A Traction Unit can be a Train in its own right, or it can haul or
push a Train consisting of Coaching Stock and/or Wagons.
So, a Locomotive is a Traction Unit, i.e. something which can turn
energy into propulsion, either for its own benefit or to move a train.
Does a Locomotive need to have a Driving Cab though? Debatable. You
can certainly have non-driving power cars within a Unit Train but then
they're not Locomotives. And you can have an ETHEL - Electric Train
Heating Ex-Locomotive - but then that's not a locomotive by
definition, it's an Ex-Locomotive (they were originally members of
Class 26 IIRC).
Just to confuse matters further, who remembers Class 13, the Master
and Slave units at Toton (or was it Tinsley?) Yard. These were pairs
of Class 08 locomotives. The driving cab had been removed from the
Slave loco which was driven directly from the Master loco, thus giving
extra welly when shunting long rakes of wagons around Tinsley (or was
it Toton?) Yard. But then these were numbered in a completely new
class and considered to be single locomotives, so we can't say that
the Slave on its own was a cabless locomotive.
So, my definition FWIW: a locomotive is a piece of equipment which can
draw energy (from coal, steam, oil, gas, electricity or whatever) and
use it to move itself along a track; it has one or more driving cabs;
it doesn't have accommodation for passengers; it may or may not be
capable of operating in multiple with other locos; it can almost
certainly operate in tandem with other locos; it can be used to push
or pull other items of rolling stock, subject to compatibility in
braking systems; er, that's it.
Did someone mention DVTs? That's an easy one, they're Driving Van
Trailers. D because they have a driving cab; V because they have space
for parcels, mail bags, day old chicks, bicycles and all the other
things that railways don't want to carry any more; T because they have
no means of traction on board, they can only be pushed or pulled by
something else. They're not Locomotives because they're not Traction
Units. They're not Units, Multiple or otherwise. They're just coaching
stock vehicles like a TSO or a BG or a bullion van or whatever.
Dean Lane, The Old Vitriol Works, Oldham, UK