Class 220/1 mystery

[43021HST]

I have heard that voyagers are DEMUs and according to their class number this is true, but how are they a DEMU, I have looked at one and I cant find any 3rd rail contact shoes or phantographs. Anyone got any answers?

 

[O L Leigh]

Same way a diesel-electric loco works. Diesel engine hooked up to an alternator to generate electricity for the electric traction motors. Hence no need for a pan/shoes. You're confusing them with electro-diesels that are dual mode, like the old Cl73's.

Mystery solved.

O L Leigh

 

[jopsuk]

the 1xx classes are sometimes reffered to as "DMMU" to differentiate- Diesel Mechanical Multiple units- though a lot of them have hydraulic, rather than direct mechanical, transmissions.

I think DEMUs are supposedly a bit smoother for high speed work, but suffer on acceleration, whilst DMMUs give good acceleration but tend not to be so suitable for high speeds- in general. The old Southern region DEMUs were supposed to be powered so for eventual conbversion to EMUs, and obviously there's the 125mph 180s- which have had a troubled history. When HST formations were given Multiple Unit numbers, they were classed as DEMUs, and the Blue Pullman units were also diesel-electric.

There's been no clear indication as to how a hybrid MU would be classed- the 6xx, 7xx and 8xx ranges are unused, however.

 

[Failed Unit]

Same way a diesel-electric loco works. Diesel engine hooked up to an alternator to generate electricity for the electric traction motors. Hence no need for a pan/shoes. You're confusing them with electro-diesels that are dual mode, like the old Cl73's.

Mystery solved.

O L Leigh

Opening up old can of worms

If you recall the HST also used to be classed as a DEMU, 253 and 254's (depending on length). Don't know why they ceased to be classed as DEMU's may GUESS is because the formations changed too much. Imagine if the 91's had been classed as EMU as they are about as fixed in thier formation as the HST's were in thier day.

 

[Lampshade]

Opening up old can of worms

If you recall the HST also used to be classed as a DEMU, 253 and 254's (depending on length). Don't know why they ceased to be classed as DEMU's may GUESS is because the formations changed too much. Imagine if the 91's had been classed as EMU as they are about as fixed in thier formation as the HST's were in thier day.

Correct, 43002 and 43003 for example made up 253001, but when power cars were swapped, it would have been a mix of 253001 and some other HST so the MU designation was dropped.

 

[90019]

Imagine if the 91's had been classed as EMU as they are about as fixed in thier formation as the HST's were in thier day.

Except that the 91s are separate locos from the Mk4 sets, which the HST powercars aren't.
--- old post above --- --- new post below ---

I have heard that voyagers are DEMUs and according to their class number this is true, but how are they a DEMU, I have looked at one and I cant find any 3rd rail contact shoes or phantographs. Anyone got any answers?

I think the confusion here comes from letters having different meanings depending on where they're placed within the acronym.
As an example, IIRC (correct me if I'm wrong, but I'm sure I've been told this before) one of the driving cars on the 313s was originally a BDMSO, but because the B is at the start it means battery, rather than brake, which it would be if it was DMBSO.

 

[37401]

220/1? didnt know such a thing existed only thought it was 2200xx and the 221s were 2211xx

 

[HSTfan!!!]

I think DEMUs are supposedly a bit smoother for high speed work, but suffer on acceleration

surely the voyagers are one of the better accelerating units on the network?

 

[ukrob]

Except that the 91s are separate locos from the Mk4 sets, which the HST powercars aren't.

Of course they are.

 

[royaloak]

Oh the HST thing again! :roll:
Answering the OP-

The 220/221s are Diesel Electric Multiple Units, ie the diesel engine drives an alternator which produces the electricity which is fed to the traction motor(s) which drive the wheel(s). the electricity is produced on board and NOT taken from the infrastructure like an Electric Multiple Unit.

The 180s are Diesel Mechanical Multiple Units, ie the diesel engine drives into a gearbox and then it drives the wheels, same basic principle as a lorry really.

 

[Oswyntail]

Of course they are.

Well yes and no. The 91s were designed with a freight role as part of the specification (hence the blunt cab) and so would operate without their Mk4s. But the 43s were never considered as anything other than the power cars in a fixed passenger formation, and, AFAIK, have never been seen on anything other than that. I would guess that they were "reclassified" as locomotives for asset register or maintenance cycle purposes.
As for the superior acceleration of the 220/221, that is surely down to the power/weight ratio. This had to be made that favourable once the decision had been made that the superiority of DEMU at high speed was critical.

 

[ukrob]

Well yes and no. The 91s were designed with a freight role as part of the specification (hence the blunt cab) and so would operate without their Mk4s. But the 43s were never considered as anything other than the power cars in a fixed passenger formation, and, AFAIK, have never been seen on anything other than that. I would guess that they were "reclassified" as locomotives for asset register or maintenance cycle purposes.
As for the superior acceleration of the 220/221, that is surely down to the power/weight ratio. This had to be made that favourable once the decision had been made that the superiority of DEMU at high speed was critical.

I know what the 91s were designed for, but to say that they are locomotives and HST powercars are not is rubbish.

And they have been used on services other than with HST trailers. With mk4s+91 and back to back hauling a sleeper has happened before too, both of which spring immediately to mind, not to mention the Network Rails powercars.

 

[LE Greys]

I would guess that they were "reclassified" as locomotives for asset register or maintenance cycle purposes.

It was actually because they kept on becoming separated from their 'own' sets whenever they went for a B-exam, and it would have been an absolute pain in the backside to repaint the set numbers every time. After this, power cars began to swap about more often, including some occasions after failures and even (I think) one booked swap at Waverley during a scheduled stop on an XC service. If you keep an eye on PC and set numbers, you will notice that they tend to keep pairs together if they can synchronise the maintenance cycle, but this gets disrupted sometimes.

On the unit numbering issue, wasn't there a BMU at one point, a battery multiple unit. Any idea what that counted as? Also, why are some 3rd rail EMUs 4XX and others 5XX? For that matter, if IEP gets built as a 'dual-mode', will it be an electro-diesel multiple unit, making it a Class 601?

 

[jopsuk]

4xx is Southern Region DC, 5xx is all other DC (not nessecarily 3rd rail).

The 4xx series even has some sort of order (more so than other series) to it (not stuck to rigerously though)- see here for more.

AC/DC dual voltage units are mainly classed as AC- techincally, 444, 450, 458 and 460 are Dual voltage capable, but are classed as DC- whilst similarly 376 units have no pantograph (as do many 375, 377 and 378) but are classed as AC. Confusing and not always logical.

 

[Geezertronic]

220/1? didnt know such a thing existed only thought it was 2200xx and the 221s were 2211xx

I think the OP probably meant 220/221 not a sub-class

 

[Oswyntail]

I know what the 91s were designed for, but to say that they are locomotives and HST powercars are not is rubbish.

And they have been used on services other than with HST trailers. With mk4s+91 and back to back hauling a sleeper has happened before too, both of which spring immediately to mind, not to mention the Network Rails powercars.

OK, most things have been used for developmental (HST/91) or emergency (2pc plus a rescued sleeper going back to Laira). The NR set is essentially a converted HST set anyway. But I doubt there has ever been a service where an HST power car has hauled freight, or a MK1/MK2/MK3 (non-HST) or even MK4 where they were the primary power provider and not there in case of C91 failure. They were designed to be part of a fixed formation, and it is quite logical not to consider them as locomotives.

 

[ralphchadkirk]

Klambert - A DEMU uses the diesel engine to drive an alternator to power the traction motors, as RoyalOak says.
I know you are from the Mid-Hants as well, and you will notice that the Hampshire Unit is a DEMU, but has no pickup shoes or otherwise.

 

[ukrob]

OK, most things have been used for developmental (HST/91) or emergency (2pc plus a rescued sleeper going back to Laira). The NR set is essentially a converted HST set anyway. But I doubt there has ever been a service where an HST power car has hauled freight, or a MK1/MK2/MK3 (non-HST) or even MK4 where they were the primary power provider and not there in case of C91 failure. They were designed to be part of a fixed formation, and it is quite logical not to consider them as locomotives.

You said:

But the 43s were never considered as anything other than the power cars in a fixed passenger formation, and, AFAIK, have never been seen on anything other than that

Talk about moving the goal posts.

And yes, they were designed to be part of a fixed formation - but they were designed over 35 years ago.

 

[A60K]

On the unit numbering issue, wasn't there a BMU at one point, a battery multiple unit. Any idea what that counted as?

There were the Class 419 Motor Luggage Vans on the Southern Region - normally 750v DC powered, but with batteries to enable them to go wandering off on unelectrified quayside lines. I think there were some battery locomotives developed, possibly for the Moorgate branch, from some old stock, but can't remember anything more.

 

[Crossforth]

How true is it that Virgin are ordering a pantograph coach for their voyagers?

I assume that is a load of rubbish?

 

[Lampshade]

How true is it that Virgin are ordering a pantograph coach for their voyagers?

I assume that is a load of rubbish?

There is some truth to it, it all depends on the next franchise.

 

[Crossforth]

I thought it was something that just came out the rumour mill

Their 221s will then in theory be reclassified, won't it?

 

[Pumbaa]

Virgin are working with Bombardier looking at the feasilbiity of adding a Panto coach to Voyagers, thus lengthening them and providing them with power for under OHLE. This is forming part of their bid to retain the franchise. Pointless really, as they're not going to get the franchise again.

Also heard today that they managed to persuade Alstom to keep the opportunity to add the remaining 390 coaches open until June, so when IEP gets shelved after the election the coaches can be ordered then. VT is keen to order them off its own back, it doesn't want the logistical nightmare of having two separate fleets.

 

[Crossforth]

Why don't you think they will get the franchise again?

 

[theblackwatch]

I know what the 91s were designed for, but to say that they are locomotives and HST powercars are not is rubbish.

And they have been used on services other than with HST trailers. With mk4s+91 and back to back hauling a sleeper has happened before too, both of which spring immediately to mind, not to mention the Network Rails powercars.

HST power cars have never been used with Class 91s and Mk. 4 stock, they ran with 91s and HST trailers.

 

[ukrob]

HST power cars have never been used with Class 91s and Mk. 4 stock, they ran with 91s and HST trailers.

Quite right, my mistake.

My point still stands though. They were designed as fixed formation sets, but they are not.

 

[royaloak]

Does it really matter? I mean as long as they do the job who cares, why does everything have to "fit" in one category or another?

 

[ukrob]

Does it really matter? I mean as long as they do the job who cares, why does everything have to "fit" in one category or another?

No, it doesn't 'really matter', but these forums would be very dull if discussion did not take place.

 

[royaloak]

But its the same one every month, I prefer to discuss DIFFERENT things, and TBH we are never all going to agree so it goes round and round all the time.

 

[90019]

And they have been used on services other than with HST trailers.

But not without them or whatever they're working with being modified beforehand (the sleeper was using the towbar, not the normal couplers - use that logic and everything with a cab is a loco)

not to mention the Network Rails powercars.

What about them? :?