[Speculation/History] Bi-Mode Multiple Units

fairysdad

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Were there ever any thoughts towards an early type of bi-mode by using different multiple units? For instance, coupling a 150 and a 455 together to have a diesel-third-rail hybrid? I know nothing like this happened, but were there ever any plans, or even just a consideration that this might be possible?

I use the 150/455 option as an example, not because I think it would work with these two classes, but from the outward appearance (from a passenger POV) they are the same, both derived from the Mk III coaches. I know that the actual workings of these trains are completely different - not least because one is diesel and one is electric! - but maybe when they were being designed and built, or even as-built before the years of alterations and refurbishments etc have diverged them even more.

Would this even be possible now - for instance (not that there would be any use for it), the thread on the 'locked door' on the 350s suggests that this particular subclass of the 350s was after an order of 450s was curtailed, with the implication that aside from the 450s being third-rail and the 350s being overhead, they are basically the same type of train (again, alterations and refurbishments notwithstanding).

Of course, in today's world of new trains, this would be very unlikely to happen with different manufacturers doing different things according to what the specific TOCs and the DfT want to do. But in theory, could this happen now? Not like the 80x units which is one train that can be diesel or electric, but two independent units, one of which can be used as a DMU when on its own, one of which is an EMU on its own, but can couple together to use whichever traction is necessary like an 80x unit does. I guess there's no need for this at all, given that the bi-mode options can be fitted into one unit, but this is just in theory.

(Of course, 'in theory', anything is possible, so perhaps it's more of a practical-theory rather than a theoretical-theory question!)
 
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Midnight Sun

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Back in the 70's and 80's the last train to Bournemouth and Salisbury was formed of a 4VEP (Bournemouth) and a class 33 plus a 4TC (Salisbury). This combo would run to Basingstoke from Waterloo where it would spit.
 

big all

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thumper 1111 could work with emus with an emu jumpers fitted the 7 position power handle was altered to work off a standard emu 4 position controller shunt series parallel and weak field
not sure if it actually was used in anger or fully just an experiment
 
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Spartacus

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One interesting application was when the 91s were introduced and some power cars were modified to work as surrogate DVTs, and were still powered, capable of working with the 91 at the other end. I've heard performance was rather good! I suppose if you wanted ones could be converted again (the equipment was removed from the originals, leaving only the buffers), capable of assisting during a failure or being switched on for a bit of extra umph, though probably not working on it's own under normal circumstances on unelectrified sections.
 

edwin_m

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The class 210 prototype in the early 1980s was essentially a modern version of the Thumper, with a diesel engine above the floor and electric transmission. It used the class 317 bodyshell and was designed to multiple with 317s. The idea was for it to be coupled to an EMU on a commuter working and then uncouple and continue as a through service beyond the limit of electrification. Two prototypes were built and trialled but the 210 was considered too expensive. After ordering two types of prototype BR went on to purchase the 150. The rest is history with a series of Sprinters and derivatives with non-electric transmission, none of which could multiple with EMUs.
 

DelW

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Were there ever any thoughts towards an early type of bi-mode by using different multiple units? For instance, coupling a 150 and a 455 together to have a diesel-third-rail hybrid? I know nothing like this happened, but were there ever any plans, or even just a consideration that this might be possible?
Not counting as a bi-mode as they weren't both coupled up at the same time, but the original Weymouth electrification sort-of worked that way. Through sets of trailer coaches (usually 2 x 4TC) were pushed from Waterloo to Bournemouth (or hauled back) by a high power EMU (4REP) at the London end, then hauled to Weymouth (or pushed back) by a class 33 at the country end.
In the days before trains had computers that need to be re-booted, the coupling and uncoupling operation was reputedly quite slick (and had plenty of practice of course).
 

Julia

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One interesting application was when the 91s were introduced and some power cars were modified to work as surrogate DVTs, and were still powered, capable of working with the 91 at the other end. I've heard performance was rather good!
I got a special preview trip on one of these - before the Mk 4s arrived. I recall one of the engineering staff telling me that they had initially intended the power car to idle all day, just providing lighting etc. for the Mk 3 set, but that caused problems with the engines (build-up of claggy gunk leading to fire risk?) so the plan was changed to having them power the train in addition to the 91. They certainly could make sprightly starts!
 

Journeyman

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When the Hastings DEMUs were ordered, consideration was given to fitting them with equipment that would allow them to operate as EMUs over the electric sections at the London end of the route. Apparently it was dismissed as too complicated and too heavy to add the extra kit, but it would have made them effectively multiple-unit versions of the later Class 73 loco.
 

big all

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When the Hastings DEMUs were ordered, consideration was given to fitting them with equipment that would allow them to operate as EMUs over the electric sections at the London end of the route. Apparently it was dismissed as too complicated and too heavy to add the extra kit, but it would have made them effectively multiple-unit versions of the later Class 73 loco.
although to be fair whilst not overly crowded the other half off a 73 was fully for the electrical gubbins and shoe gear operation isolation and foot pump incase off flat battery and no air to push the shoes down on the juice
so little space for passengers even if it could be further condenced
 
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swt_passenger

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Operating a combined DMU and EMU formation such as a 150/455 in multiple as per the first post doesn’t actually give you a bimode through train, because the 150 is not adequately powered to haul a dead 455 away from the juice. Likewise the 455 cannot haul a dead 150 while on the juice.

The Bournemouth to Weymouth routine is a bit of a red herring in this context, it’s really just a loco drag beyond the third rail extent. Possibly more comparable with taking a 390 to Holyhead...
 

gingertom

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just wondering whether a 185 and 350 could operate together? They are from the same Siemens' Desiro family, and the 185s have enough grunt to spare to drag around some dead weight away from the wires.
 

Emyr

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Given a DEMU has a diesel engine, an alternator and then a relatively conventional electrical drivetrain, you could have additional contacts in the coupler to extend the DEMU power distribution circuits into the coupled EMU's circuits. You'd need the DEMU to have some hefty batteries or supercapacitors so that a reserve can be built up while cruising and decelerating and then deployed for acceleration.
 

JohnMcL7

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Do the 68's and 88's run in pairs to allow them to run on either diesel or electric power? There was a recent discussion about them and someone mentioned an issue where the 68 can't change electric/diesel mode which means the 88 needs to lead but didn't know if that was just theoretical.
 

jopsuk

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it was possible, and did happen, that weymouth trains could have the 33 to/from Waterloo in multiple with the 4REP, as far as I'm aware.
Given a DEMU has a diesel engine, an alternator and then a relatively conventional electrical drivetrain, you could have additional contacts in the coupler to extend the DEMU power distribution circuits into the coupled EMU's circuits. You'd need the DEMU to have some hefty batteries or supercapacitors so that a reserve can be built up while cruising and decelerating and then deployed for acceleration.
As of yet, no-one has dared try to run traction power through an Auto Coupler- would need much heftier connections and cables than found in the current designs.
 

61653 HTAFC

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As of yet, no-one has dared try to run traction power through an Auto Coupler- would need much heftier connections and cables than found in the current designs.
If it ever could be made to work safely and reliably, it could also reduce the "ripple effect" of EMUs working in multiple, as it would potentially allow some pantographs to be lowered.
 

rebmcr

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Do the 68's and 88's run in pairs to allow them to run on either diesel or electric power? There was a recent discussion about them and someone mentioned an issue where the 68 can't change electric/diesel mode which means the 88 needs to lead but didn't know if that was just theoretical.
I think further in that thread is a report of a train with 68 and 88 both providing traction.
 

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