Not quite. Two cars will have diesel engines under them, one will have the motors and traction equipment, leaving one 'quiet' car, which will be the vehicle with the toilet in it.
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Porterbrook Cl.769 'Flex' trains from 319s, initially for Northern
- Thread starter northwichcat
- Start date
Not quite. Two cars will have diesel engines under them, one will have the motors and traction equipment, leaving one 'quiet' car, which will be the vehicle with the toilet in it.
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R
RailUK Forums
I believe the power generation will be AC via the two 500HP motors per train. As D365 says the power will then be converted to DC to power the motors. You have thought having to go the expense of the engine addition, conversion entirely to AC would have been cheaper and you would no longer need to haul round a heavy AC to DC regulator.
Kite159
Veteran Member
They will probably work, but will be slow at gaining any sort of speed quickly
319s are not the best known for their acceleration, adding on the weight of those engines (plus fuel and other bits) will only make acceleration worse.
319s are not the best known for their acceleration, adding on the weight of those engines (plus fuel and other bits) will only make acceleration worse.
edwin_m
Veteran Member
The electric transmission will help somewhat versus a Sprinter, but only a bit more than 25% of the weight will be on powered axles rather than 50% for Sprinters and many modern EMUs. This may make them slow to accelerate at low speeds and (like the 319) prone to slip in poor adhesion. At higher speeds the power available will limit performance, which might be similar to a 150 but worse than a 319 on electric. As a 150 only goes up to 75mph the 769 may struggle to get much above that in diesel mode.
It doesn't work like that.
If you're thinking of AC motors, these require AC at a frequency that changes as the train accelerates. AC from the wire is at a constant frequency and AC drives convert it to DC before inverting it to produce the sort of AC the motors need. AC motors would save a bit of weight and might improve performance a bit, but would be a big cost as all the existing traction equipment would need replacing as well.
The "AC to DC Regulator" is no more than a bunch of diodes and pretty small compared to a diesel engine and a fuel tank. If you tried to drive an AC motor off a diesel engine without converting the power to DC and inverting it again, you'd have to synchronise the diesel with the motors rather like a mechanical transmission. Complete with some sort of clutch between the engine and the alternator, as the engine can't give power at zero speed to start the train.
Thanks Edwin. I am merely an armchair commentator and I am always happy to be corrected! I didn't realise a diesel generator could not be be hooked up to straight up AC powered motors with out the use of inverters. It does make sense as you say modern EMUs do of course use inverters even where everything is AC. I probably had the name wrong but I am sure there is some heavy component on the 319s that does the work of shuttling down 25 thousand AC votes to 750 DC volts.
There will be a transformer (25kV>750V part) and a rectifier (AC>DC part) that together turn the 25kV AC from the overhead into 750V DC that is then used to power the motors.
Yes cheers Dom. Rectifier rather than regulator and transformer my mistake. Those are the components I was imagining could be got rid of if everything was AC but Edwin as corrected me it would need more components to get it to work eitherway.
Bletchleyite
Veteran Member
Yeah, you could convert 455s, the downside being the lack of AC capability. If there are enough 319s, they're probably the best bet as a bi-mode rather than DMU is created for no more money.
43096
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But if you just want a straight DMU, then a 455 would be better. Reduce it to three cars with engines under the driving cars and you would have better performance than a 150. Ideal as Pacer replacements for the Valleys I would suggest.
Bletchleyite
Veteran Member
I suppose the other advantage of 455s is that some will become available (from SWR) which have both brand new traction packages and near brand-new interiors, the layout of which are probably ideal for the Valley Lines.
43096
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Correct. Add a toilet in to one of the driving cars and you have a very useful train. The Exmouth/Exeter/Barnstaple/Paignton “Devon Metro” is another obvious candidate.
Bletchleyite
Veteran Member
Added bonus I suppose: already set up for guarded operation so no need to convert from DOO. Though I guess a few extra panels might be useful.
Bevan Price
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Not with 319s. Any Sprinter (or even Pacer) can out-perform a 319 at speeds up to 35/40 mph. Adding extra weight to the 319s when converting them to 759s will only make that worse.
(See 319 versus 156 acceleration curves below)
Door controls, PA and cab-to-cab equipment is already fitted in one panel on each side of each coach in the passenger saloon, apart from the 508 trailer of 455/7s.
Bletchleyite
Veteran Member
Sorted then...remove the Class 508 car, bolt the engines on and away you go!
Agreed, but unfortunately though, Welsh Govt are not using a common sense approach to procure the next Valley lines operator or the rolling stock to be used.
5 x 2 coach 144s go off lease on 15th September, 8 more on 5th January 2019 and the 10 x 3 coach 144s on 31st March 2019. Them and Porterbrooks 5 GWR 143s would enable large numbers of 150s to go for upgrade.
Sounds like it would be ideal for Buxton to Manchester Piccadilly because compared to 150s any timing difference between Buxton and Hazel Grove would be made up on electric traction between Hazel Grove and Piccadilly. Whether the timetabling could be made to work for May 2018 is a different matter.
Excluding Northerns 8 undergoing conversion there are 45 x 319s off lease and 5 are allocated to W&B for conversion. Brush would struggle to convert another 40 by the end of 2019 and I doubt there is the market for that many. 11 is probably the right amount for Northern in the long term. If the valleys lines are wired to Pontypridd and Bargoed then maybe W&B could use 16-20 but that is unlikely. I am struggling to think of another ToC that might want to order any in the next couple of years. Once 2020 arrives and pacer withdrawal and PRM TSI are no longer an issue new builds will probably make more financial sense.
Running through the next round of franchise announcements (ignoring W&B):
- Southeastern - no lines that are not electrified, so unlikely
- West Coast - 125mph tilting trains are required, so that's a no from them
- East Midlands - limited electric lines with most of the distance of the wires being for 125mph services, so fairly unlikely
- Cross Country - 125mph stock mostly required although the other routes could also benefit from extra stock however reducing top speed from 100mph would unlikely to work well, so again a no.
- Great Western (post 2020 start date) - there could be done places where the 769's could work well (i.e. North Downs Line, where they would increase capacity a little and improve loading/unloading times for busy services), but without a higher top speed or electric sections (or at least ejected sections due within a few years) they could be a bit of a bad fit, so a few could be a possibility.
- Thameslink/Southern/Great Northern - a limited of routes that are not electrified but given the risk of knock on delays of something goes wrong an unlikely home for them, so probably a no
- Chiltern - with their use of bubble cars there could be a case for a few, but again other options would be better, so likely to be a no
I could go on, but given that anything beyond that would be starting in 2023 (even then the possible franchise, i.e Northern, would be 2025) it is unlikely that the units would be stored for that long and if they are their condition could mean that they were costly to convert.
D365
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Interesting, do you have a source for that graph or for the data?
I still think there's a future for this type of conversion beyond the 769 Flex, whether it be from electric to bi-mode or electric to diesel. I don't expect it'll suddenly take off and we'll end up with hundreds of "Flex" type units, but it is an alternative which could tide parts of the network over until sufficient new stock has been procured from now until the mid 2020s or so. Beyond that, I think something like a three-coach "455 DMU" could be useful to help re-open branch lines.
Also, if the graph is authentic, is it for both types empty full or even crush loaded and what was the fuel load of the sprinter? The heavier the passenger/fuel load load, the more the sprinter would suffer. If the curve is representative and repeatable, the difference would only affect timetabling where there were several short runs meaning that trains needed to slow down before reaching 40mph, - even then it would only make about 5 seconds difference per stop.
edwin_m
Veteran Member
The Buxton line has some severe gradients and I think also suffers from adhesion problems, so I would hope Northern give them a trial run in autumn if they are thinking about using 769s.
a_c_skinner
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Apologies if I've missed this but IIRC Porterbrook modelled performance on the Buxton line and said it would be (in theory) capable of using existing paths.
I guess all this hangs on making them work reliably at a reasonable cost. My (Crayola) take on this is that all the via Lancaster services to Morecambe, Leeds, Barrow and Windermere could all use 769s if they work reliably and properly. Fleet in one area which uses 319s too, all services that make use of electric traction for parts of the routes.
Most of this has been about 25kV OLE routes, there must be some that are part 3rd rail as well where 3rd rail infill or extension isn't going to happen.
I guess all this hangs on making them work reliably at a reasonable cost. My (Crayola) take on this is that all the via Lancaster services to Morecambe, Leeds, Barrow and Windermere could all use 769s if they work reliably and properly. Fleet in one area which uses 319s too, all services that make use of electric traction for parts of the routes.
Most of this has been about 25kV OLE routes, there must be some that are part 3rd rail as well where 3rd rail infill or extension isn't going to happen.
I don't I think any demand will be satisfied from 769's and looking further ahead you need to start looking at new build or the newer DMU's which may become available to replace 15x rather than a 455 which is already a somewhat ancient train, plus we already have the D train which customers are not exactly falling over themselves in the rush to buy.
Bletchleyite
Veteran Member
455s are old, but once again people are forgetting a train is more like a house. There's no shortage of enthusiasm for HSTs, is there? They're ten years older than 455s.
The SWR 455s are more like a Victorian house that has just received a full refurbishment including a rewire and new boiler. Nobody would complain about living in one of those, would they?
The SWR 455s are more like a Victorian house that has just received a full refurbishment including a rewire and new boiler. Nobody would complain about living in one of those, would they?
northwichcat
Veteran Member
Worth noting on the Buxton route pathing is most likely to be an issue between Hazel Grove and Manchester, which is electrified. If they based it on calling at Heaton Chapel and Levenshulme then it should be able to do the electrified section much quicker than a 150.
northwichcat
Veteran Member
Not sure about that analogy. OK you can make an old house look like new internally but would it be economically viable to move the external door positions or to widen the carriages on a train? Changing where doors & windows are positioned and building a porch/extension are both viable modifications to make to a house.
other
There is a slight difference between a HST and a 455's though isn't there, one is a comfortable Intercity train most of which have had significant updates over the years including new engines and new interiors, while the other is a somewhat less comfortable clapped out old commuter train which also wasn't designed to be a DEMU.
I don't doubt it could be done but whether the economics really add up for a train with a 10 to 15 year lifespan as opposed to buying a new CAF DMU/Stadler Train train I'm not so sure. Ideally if your going to do DEMU or Bi-mode converts newer generations of EMU's would be better but they might be more difficult to convert.
In the case of HST's its mainly a case of mainly sorting the doors out, and clearly it was decided it was a worthwhile solution in that instance, compared to probably the only other serious options of new Loco Hauled Trains or AT300's.
There is a slight difference between a HST and a 455's though isn't there, one is a comfortable Intercity train most of which have had significant updates over the years including new engines and new interiors, while the other is a somewhat less comfortable clapped out old commuter train which also wasn't designed to be a DEMU.
I don't doubt it could be done but whether the economics really add up for a train with a 10 to 15 year lifespan as opposed to buying a new CAF DMU/Stadler Train train I'm not so sure. Ideally if your going to do DEMU or Bi-mode converts newer generations of EMU's would be better but they might be more difficult to convert.
In the case of HST's its mainly a case of mainly sorting the doors out, and clearly it was decided it was a worthwhile solution in that instance, compared to probably the only other serious options of new Loco Hauled Trains or AT300's.
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Bletchleyite
Veteran Member
Yes, but these are not intended for lines where you would get a "comfortable Intercity train". They are basically a way of getting more Class 150s for lines that would use Class 150s anyway.
The 455s have new traction packages and new interiors roughly equivalent to a 450.
The 455s have new traction packages and new interiors roughly equivalent to a 450.
Yes but your replacing like with like where as new trains are likely to offer an improved travelling environment compared to a 150, how many comments do we get on here as it is that 150's are not a great step forward over a Rail Bus. At least with the Northern current train plan there will be a significant step forward in quality on some services and particularly the longer distance services, where as a Northern Replacement using only D trains, or 769's or converted 455's etc, wouldn't have been a great step forward, and the evidence so far is that the TOC are not exactly bashing down the door to get these trains, and once the potential advantage of getting these trains before the 2020 deadline disappears then I think these solutions will head for oblivion.
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