I forgot to add the caveat 'according to Wikipedia' to my earlier post. Unless somebody who knows for sure comes forward we'll remain unsure.
I do remember reading it at the time, probably in Modern Railways. It was specifically mentioned as allowing a DMU and EMU to run in multiple out of London*, and then split for the DMU to continue to some non-electrified destination.
I’m sure at the time that the idea was for a 210+317 to work as far as Bedford with the 210 carrying on to Leicester. 40 years may have dimmed the memory somewhat however.
Wasn't this also an idea when the (never built) theme park was proposed for Corby; with the DMU going forward from Bedford to serve the theme park visitors.
As the 317s worked that route at the time and the 210 probably couldn't multiple with anything else, it would be an obvious choice for a first application. But Leicester seems a bit far to go in something that might have been better than a Pacer but was the same interior as a 317 but noisier. I can't remember if the idea of serving Corby was on or off at the time.
Definitely used in anger, if you search the forum for "EML" you will find discussion about this, primarily related to Salisbury (33+TC) and Southampton (VEP) services which combined at Basingstoke, or vice-versa.
EDIT See attached from 16/5/88 to 14/5/89 working timetable; 2B69 23:45 Waterloo to Bournemouth and Salisbury. Front portion EMU (4-VEP) I think, then 33+4-TC. Split at Basingstoke with 2L49 leaving shortly after the Bournemouth portion to Salisbury.
I definitely think working it around locos would be best. Maybe even just turn the diesel off over electrified sections since the dead weight wouldn't be too great compared to a DMU.
A loco would be quite literally that, dead weight, equivalent to 2-3 coaches of a DMU. So it would probably get removed at the station where electrification started, as used to happen with the Weymouth push-pulls (unpowered 4TC unit coupled to a powered 4REP east of Bournemouth and to a Class 33 further west). A DMU would add weight but also increase the passenger capacity.
MUs just make more sense for passenger service - you can use the entire length of the train for accomodation. If the DMU is built with a modular powertrain then there's no advantage from the flexibility of being able to replace a diesel locomotive with an electric, as per speccing the old Bournemouth/Weymouth service.
I suppose that's sort of a half and half solution. Have EMU stock capable of being loco pulled, and then attach and detach the diesel loco when required.
I am sure I recall a grey day at Lille Europe, waiting for the Eurostar back to London and seeing through the fence a pair of TGV units coupled together with what looked like a 25kV connector at roof level between the power cars. Or was I dreaming? Possible, because I was thinking how nice it would be to just get on the TGV to Avignon or somewhere!
Between carriages within a unit, but most certainly not between units!
This is a really good video showing a IR4 and IC3 combo leaving Odense in both electric and diesel.
Technology still hasn't delivered a way of sending traction power through a non-permanent coupling, so the closest available method of operation to what you suggest would be to use the DMU to supply ETS to an otherwise-dead EMU... and that's not very far from how LNER already drag/push their electric-only Azumas around with their bi-mode ones (they just use a diesel generator on the 'pure' EMU to generate ETS).
It's a bit odd the first few times you hear the obvious traction motors followed by the burst of exhaust noise - but much less now that you can also get it from a diesel FLIRT
... And 769s, as has been commented by almost everybody who has travelled on them. I know they are an integrated unit, but the effective audible and visual contradiction is similar.Technology still hasn't delivered a way of sending traction power through a non-permanent coupling, so the closest available method of operation to what you suggest would be to use the DMU to supply ETS to an otherwise-dead EMU... and that's not very far from how LNER already drag/push their electric-only Azumas around with their bi-mode ones (they just use a diesel generator on the 'pure' EMU to generate ETS).
It's a bit odd the first few times you hear the obvious traction motors followed by the burst of exhaust noise - but much less now that you can also get it from a diesel FLIRT
