Will existing DMUs will be re-engined to lower-emission engines to keep them going for longer, as e.g. Class 56s, or lengthened?

If there is a shortage of DMUs, and new DMUs are no longer allowed to be bought in the future, do you think that some DMUs will be re-engined to have newer, lower-emission engines, as an acceptable way to get around this and still be better than they used to be, as has happened with some Class 56s to form Class 69s? Or could they be lengthened with more vehicles, so there are longer single sets rather than running in multiple, to not technically increase the number of new diesel trains, but while increasing capacity?

Battery trains will replace the whole idea of DMUs in due course I'd say. 150s are nearly 50 years old on original engines so I can't see them being changed in that way (though they will be fully rebuilt many times) - generally emissions regulations have grandfather rights.

Bletchleyite said:

generally emissions regulations have grandfather rights

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The converse of this is that new engines don't, and they often need extra equipment to comply with the regulations that apply to them. Fitting these in the limited underfloor space could be a challenge, and I suspect the bodywork of some of these classes limits their remaining life so it's not justifiable to spend money on major modifications.

edwin_m said:

The converse of this is that new engines don't, and they often need extra equipment to comply with the regulations that apply to them. Fitting these in the limited underfloor space could be a challenge, and I suspect the bodywork of some of these classes limits their remaining life so it's not justifiable to spend money on major modifications.

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Particularly as it's often said that a new 20m DMU wouldn't be possible due to the extra space taken by modern emissions kit (and the toilet tank). FLIRTs of course have short vehicles but that's by having the underfloor gubbins above the floor instead taking platform length.

I suppose it’d be possible to introduce a FLIRT-like power car into DMUs.

RUK said:

as an acceptable way to get around this

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I can't think of a logical reason that re-engine-ing would be more "acceptable" than building new DMUs? If we are effectively hacking to "get around" a rule then is it not better to just remove the rule?

Egg Centric said:

I can't think of a logical reason that re-engine-ing would be more "acceptable" than building new DMUs? If we are effectively hacking to "get around" a rule then is it not better to just remove the rule?

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GBRf did the Class 56 to Class 69 conversion because it was a lot cheaper than buying new locomotives. Newer engines are less polluting than older ones - that’s how they could justify replacing the old Class 56 engines with Class 66 ones, even though new-build Class 66s were no longer allowed, due to their engines not meeting newer emissions standards.

The NT855 engine series has a vast installed base and a good eco system of suppliers to keep it going for some time yet. So as long as it retains grandfather rights on emissions then it should keep going indefinitely. Hopefully the engines and transmissions are being recovered off the withdrawn units so they have a good pool of spares crankcases.

RUK said:

GBRf did the Class 56 to Class 69 conversion because it was a lot cheaper than buying new locomotives. Newer engines are less polluting than older ones - that’s how they could justify replacing the old Class 56 engines with Class 66 ones, even though new-build Class 66s were no longer allowed, due to their engines not meeting newer emissions standards.

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I understand that, but that was in the context of a fragmented legislative system where the aim was for a private company to be getting around rules that were ultimately government-directed, and with locos that had a lot of time left in them aside from the engines.

Doing this with 150s is different because a) aiui there are many age related issues with them, not just the engine b) more importantly some strategy like this would essentially be the government trying to get around its own rule! Either it should scrap the rule or it should stick to the spirit of it rather than try to exploit a loophole.

RUK said:

GBRf did the Class 56 to Class 69 conversion because it was a lot cheaper than buying new locomotives. Newer engines are less polluting than older ones - that’s how they could justify replacing the old Class 56 engines with Class 66 ones, even though new-build Class 66s were no longer allowed, due to their engines not meeting newer emissions standards.

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You do realise that the Class 69 engine is the very same one that a Class 66 uses?

RUK said:

I suppose it’d be possible to introduce a FLIRT-like power car into DMUs.

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How would that work? FLIRTs use their diesels to generate electricity for the electric motors that drive the wheels. DMUs drive their wheels directly from the motors.

JamesT said:

How would that work? FLIRTs use their diesels to generate electricity for the electric motors that drive the wheels. DMUs drive their wheels directly from the motors.

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By doing the kind of re-engineering exercise that means building new would be easier.

Though actually you could probably put an electric motor on the end of the drive shafts instead of the engines & transmissions. It probably wouldn't be simple or worth the effort.

I would think the best case for re-engining existing DMUs would be to add some sort of hybrid capability, with a battery and a diesel engine to act as a range extender- not a million miles from the 769s and 230s, although with an added battery.

But the choice of an EMU train for conversion in those two cases (319s and D stock) suggests that EMUs might be easier to convert into that sort of hybrid train.

The Pelican said:

I would think the best case for re-engining existing DMUs would be to add some sort of hybrid capability, with a battery and a diesel engine to act as a range extender- not a million miles from the 769s and 230s, although with an added battery.

But the choice of an EMU train for conversion in those two cases (319s and D stock) suggests that EMUs might be easier to convert into that sort of hybrid train.

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There was a project to convert a class 165 to hybrid with a battery. It’s noticeable that the test vehicle has been returned back to all diesel and Chiltern are likely to get new replacement stock.

43096 said:

You do realise that the Class 69 engine is the very same one that a Class 66 uses?

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Yes - the point is that new whole Class 66 locomotives weren’t allowed, so the work-around was to replace older, more-polluting Class 56 engines with Class 66 engines, because stand-alone new engines could still be imported, even though new entire locomotives weren’t allowed, the benefit/reason for it being allowed being that although the Class 66 engines didn’t meet the emissions requirements for engines in new-build locomotives, they were still less polluting than those older original Class 56 engines, so there was still an overall emissions benefit, thus this “work-around” was allowed. GBRf chose the same engine as the Class 66 have for the Class 69s, so that they could keep a common pool of spare parts for economies of scale and efficiency. I suppose importing engines which were no longer allowed in new-build locomotives was still allowed, because they would be needed for other locomotives which had them for spare parts reasons.

I am drawing the same parallel with DMUs - if building new DMUs is no longer allowed, then re-engining them to get more life out of the rest of the train is still less polluting than keeping the existing, more-polluting engines, and has the additional environmental benefit of re-using the rest of the train, thus using less material than building a new train, as well as being cheaper, like with the Class 424 Networker Classic idea.

JamesT said:

How would that work? FLIRTs use their diesels to generate electricity for the electric motors that drive the wheels. DMUs drive their wheels directly from the motors.

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I just think of the power car like a separate locomotive. As I understand with the Sprinters and Class 220/221/222 etc., each car has its own separate engine, which is why you can just take any car from any unit and stick it into another set to increase the length of the unit. If you can’t do that due to space under each the carriages not being sufficient now, then stick trailer cars in, and add a power car like a locomotive instead - maybe take shorter Electrostar trailer carriages without adding engines to them, (since Electrostars can be replaced with newer EMUs), and put them into Turbostars, and add a separate power car.

JamesT said:

There was a project to convert a class 165 to hybrid with a battery. It’s noticeable that the test vehicle has been returned back to all diesel and Chiltern are likely to get new replacement stock.

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I think it was technically successful but not economic to convert the rest of the fleet, as the main benefit was fuel savings but diesel was relatively cheap at the time. It was reverted because they didn't want a non-standard unit.

RUK said:

I just think of the power car like a separate locomotive. As I understand with the Sprinters and Class 220/221/222 etc., each car has its own separate engine, which is why you can just take any car from any unit and stick it into another set to increase the length of the unit. If you can’t do that due to space under each the carriages not being sufficient now, then stick trailer cars in, and add a power car like a locomotive instead - maybe take shorter Electrostar trailer carriages without adding engines to them, (since Electrostars can be replaced with newer EMUs), and put them into Turbostars, and add a separate power car.

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That would involve building new power cars which would only have a short life because the DMU cars they worked with would themselves be near end of life. Taking trailers from EMUs raises the question of what to do with their motored cars.

RUK said:

I just think of the power car like a separate locomotive. As I understand with the Sprinters and Class 220/221/222 etc., each car has its own separate engine, which is why you can just take any car from any unit and stick it into another set to increase the length of the unit. If you can’t do that due to space under each the carriages not being sufficient now, then stick trailer cars in, and add a power car like a locomotive instead - maybe take shorter Electrostar trailer carriages without adding engines to them, (since Electrostars can be replaced with newer EMUs), and put them into Turbostars, and add a separate power car.

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That's complex and hasn't gone well when tried before i.e. Classes 230 and 769. Better to scrap and build new than start messing round like that.

Have the steal 15x got corrosion issues so fixing them and swapping the engine is not likely to have a strong business case.

RUK said:

Yes - the point is that new whole Class 66 locomotives weren’t allowed, so the work-around was to replace older, more-polluting Class 56 engines with Class 66 engines, because stand-alone new engines could still be imported

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To me this is over regulation resulting in less than optimal solutions. Surely a brand new locomotive would be more efficent and less polluting than a reworked old one, where compromises will have been made with the design.

Unfortunately we are seeing the same thing in other areas, the Government would rather us import chemicals from half way across the world, with all the extra impact that results, than have a local energy policy that encourages local production and use (Thinking Ineos closures in Hull).

I support an environmentally responsible approach, but a lot of current decisions just dont make sense.

Equally with DMUs there will be some routes where DMU's will probably be the best solution for many years, so why not just accept it and deal with the big hitters, with my own pet peeve, long periods of diesel operation under the wires being one. Fund that and sorting out other big contributors to emissions and accept that there will be few DMUs trundling arouind on lightly used rural routes for many years, and just upgrade to the best solution that diesel technology currently allows.