Theoretically what's the most powerful diesel UK locomotive possible?

[JohnMcL7]

There's possibly a recent topic on this so please point me to it if that's the case.

I was watching a documentary about the US turbine locomotives which mentioned these are still the most powerful single prime mover there has been (even though the locos were huge and in three parts) which still stands. Which left me wondering if you were aiming to fit the most powerful diesel engine in a UK locomotive within the weight limits, what would that be? HS4000 I think is still the single most powerful UK diesel locomotive although the class 68's Cat engine is close and in a much lighter locomotive.

 

[hexagon789]

There's possibly a recent topic on this so please point me to it if that's the case.

I was watching a documentary about the US turbine locomotives which mentioned these are still the most powerful single prime mover there has been (even though the locos were huge and in three parts) which still stands. Which left me wondering if you were aiming to fit the most powerful diesel engine in a UK locomotive within the weight limits, what would that be? HS4000 I think is still the single most powerful UK diesel locomotive although the class 68's Cat engine is close and in a much lighter locomotive.

There was a proposal for a 4,600hp 'Super Deltic' in the 1960s; with modern engines and electrical equipment that could be managed with a lower axle loadings than the 19 tons quoted? There are I believe locos of over 6,000hp but whether that could be managed within axle load limits.

 

[HSTEd]

Well in terms of diesel fueled..... you can probably get absolutely enormous powers by fitting modern high performance turboshaft engines into locomotives.
The Liberty-derived Turboshafts manage something like 10kW/kg

 

[ilkestonian]

It depends to some extent on the critera you set for this theoretical loco. The US loco you quote has three units. Why stop there. Just using current loco power as an example, build thirty cabless class 68s and sandwich them between a pair of single cab examples, multi-controlled. Or why not fifty, or a hundred?

 

[JohnMcL7]

It depends to some extent on the critera you set for this theoretical loco. The US loco you quote has three units. Why stop there. Just using current loco power as an example, build thirty cabless class 68s and sandwich them between a pair of single cab examples, multi-controlled. Or why not fifty, or a hundred?

It needs to be a single locomotive with one engine and no auxiliary units. Although the US turbine locos were made up of several different units including the auxiliary diesel engine, the turbine was a single source of power. The engine should also be something sensible and designed for heavy use, not a series of Bugatti Chiron engines mounted together to get a very high power output for size.

 

[ac6000cw]

Ignoring emissions rules etc. as this is speculative thread...

If you stretched a class 68 a little into a longer (maybe six-axle) loco, I think you could get the V20 version of the Cat C175 engine into it - that would take you to around 4700hp.

The V20 version of the EMD 710 engine is around 5500hp, but it's nearly 2m longer and 6.4 tonnes heavier than the V12 (as used in the class 66/67) so fitting it in might be interesting.

The 6000+ hp engines that both EMD and GE have produced in the past for North American and Chinese locomotives are highly likely too large to fit into UK (or even mainland European) sized locos.

 

[JohnMcL7]

Ignoring emissions rules etc. as this is speculative thread...

If you stretched a class 68 a little into a longer (maybe six-axle) loco, I think you could get the V20 version of the Cat C175 engine into it - that would take you to around 4700hp.

The V20 version of the EMD 710 engine is around 5500hp, but it's nearly 2m longer and 6.4 tonnes heavier than the V12 (as used in the class 66/67) so fitting it in might be interesting.

The 6000+ hp engines that both EMD and GE have produced in the past for North American and Chinese locomotives are highly likely too large to fit into UK (or even mainland European) sized locos.

Thanks for the answer, this is the sort of information I was looking for.

 

[DPWH]

Does this exclude hybrids? Because wouldn't a hybrid running off overhead electric power be more powerful than the diesel?

 

[AM9]

Does this exclude hybrids? Because wouldn't a hybrid running off overhead electric power be more powerful than the diesel?

Yes, but then it isn't diesel powered. For example, a hybrid Traxx has electric motors with a total power output of 5.6MW, (and an OLE kit to provide that power). When away from the wires, running as a diesel, those motors are only fed with 2.2MW from a fairly moderate 3000hp diesel genset. So it is a 2.2MW diesel engine, just like a class 68 which is a 2.8MW diesel engine.

 

[ac6000cw]

Ignoring emissions rules etc. as this is speculative thread...

If you stretched a class 68 a little into a longer (maybe six-axle) loco, I think you could get the V20 version of the Cat C175 engine into it - that would take you to around 4700hp.

The V20 version of the EMD 710 engine is around 5500hp, but it's nearly 2m longer and 6.4 tonnes heavier than the V12 (as used in the class 66/67) so fitting it in might be interesting.

The 6000+ hp engines that both EMD and GE have produced in the past for North American and Chinese locomotives are highly likely too large to fit into UK (or even mainland European) sized locos.

Something I forgot about (but am well aware of) is that if you increase the engine power you also have to increase the capacity of the cooling system - so you need larger radiators and fans. So you get doubly hit as power increases...and of course the fuel consumption goes up so your usable range between re-fueling goes down...

Given where we are with fast-improving battery technology, I think a better answer for a more powerful 'self-powered' freight loco is probably combining something like a high-speed, compact, 2500hp diesel (e.g. MTU R4000 or Cummins QSK60 series) with as much battery storage as you can fit in. That way you might get to a shortish-term 5000hp or so for acceleration and hill climbing, combined with enough long-term power to roll along the flat at a reasonable speed. This also means that electric (dynamic) braking can re-charge the batteries to give fuel savings and lower CO2 emissions. Also add shore-supply capability to enable the batteries to be topped up when possible.

All you now have to do as an FOC is persuade your customers to pay more to fund the leasing costs....

 

[AM9]

Something I forgot about (but am well aware of) is that if you increase the engine power you also have to increase the capacity of the cooling system - so you need larger radiators and fans. So you get doubly hit as power increases...and of course the fuel consumption goes up so your usable range between re-fueling goes down...

Given where we are with fast-improving battery technology, I think a better answer for a more powerful 'self-powered' freight loco is probably combining something like a high-speed, compact, 2500hp diesel (e.g. MTU R4000 or Cummins QSK60 series) with as much battery storage as you can fit in. That way you might get to a shortish-term 5000hp or so for acceleration and hill climbing, combined with enough long-term power to roll along the flat at a reasonable speed. This also means that electric (dynamic) braking can re-charge the batteries to give fuel savings and lower CO2 emissions. Also add shore-supply capability to enable the batteries to be topped up when possible.

All you now have to do as an FOC is persuade your customers to pay more to fund the leasing costs....

I've thought along those lines before. That would give a battery boosted diesel a performance approaching the equivalent electric loco with the same traction motors fitted. There would be the benefit in supplementing the diesel engine with it's absolute limit of power with battery power that would allow using the short-term capabilities of electric motors to exceed their continuous ratings.

 

[JohnMcL7]

I have wondered about the application of hybrid technology for freight locomotives given the battery weight isn't an issue as it is with other cases and they need the power for acceleration and with their heavy braking they'd be able to recover energy. While it would add complexity if the diesel engine could still run the locomotive on its own with the batteries as a boost then it wouldn't cause reliability issues.

 

[DerekC]

The idea of a hybrid freight loco is not new. A company called "Railpower" has built fifty switchers of just this kind called "Green Goat" - see :

https://en.wikipedia.org/wiki/Railpower_GG20B

The Railpower GG20B Green Goat is a low-emissions diesel hybrid switcher locomotive built by Railpower Technologies Corp. It is powered by a single Caterpillar C9 six cylinder inline engine developing 300 horsepower (224 kW), which is also connected to a large battery bank where both sources combine for a total power output of 2,000 horsepower (1,490 kW). To date, there have been more than 50 GG20B electric-diesel electric hybrid switchers manufactured since their first introduction in 2004 …..

Part of the rationale for these was to reduce noise for neighbours of US freight yards. As far as I know nobody has built a main line version yet. My guess is that weight is the main problem. Also consider what happens when you need high power for a long period (such as climbing the Rockies) - all good until the batteries run down, but then you are down to a crawl. And of course going down the other side you will only recover energy from the locomotive brakes.

 

[MarkyT]

My guess is that weight is the main problem. Also consider what happens when you need high power for a long period (such as climbing the Rockies) - all good until the batteries run down, but then you are down to a crawl. And of course going down the other side you will only recover energy from the locomotive brakes.

A good case for bi-mode locomotives combined with discontinuous electrification through steep mountain sections. Some US railroads had electrification in mountain divisions, but locos had to be changed at the extremities of wiring, so as diesel locos improved, such electrification became uneconomic and was either removed or the particular routes were closed down entirely in favour of alternatives during the business consolidations of the 1960s and 70s. Bi-mode technology could avoid the loco changes clearly, and such traction could also have batteries installed to reduce emissions and noise as well as provide a traction boost for acceleration off grid. Very loud horns and constantly ringing bells in station yard areas would also have to be tackled to more effectively control noise for road freights!

 

[randyrippley]

If you simply wanted maximum power regardless of economy then you'd power it with a modern turboshaft unit with battery hybrid transmission - and I'd be tempted to use a flywheel as a booster set for acceleration as well

 

[HSTEd]

Well given that the very fuel efficient low speed diesels like those used on traditional EMD locomotives are no longer available to us..... gas turbines have improved to the point where they can achieve comparable fuel efficiency, at full load.

And thats before any hybrid or heat recovery shenanigans.

 

[xotGD]

I imagine that you could stick a fairly big fuel cell inside a loco. Might need a tender to store the hydrogen, mind.

 

[DerekC]

Well in terms of diesel fueled..... you can probably get absolutely enormous powers by fitting modern high performance turboshaft engines into locomotives.
The Liberty-derived Turboshafts manage something like 10kW/kg

Well yes, - so you could install the Rolls-Royce T406 with a maximum power of roughly 4.5MW and a weight of about 500kg - but what do you do with it? if built into a lightweight chassis it could probably set a world speed record, but to be a useful locomotive you would need to add lots of ballast. Oh, and they cost $2.2M a pop. And the rated life is 500-600 hours which doesn't sound very helpful!

 

[HSTEd]

Well yes, - so you could install the Rolls-Royce T406 with a maximum power of roughly 4.5MW and a weight of about 500kg - but what do you do with it? if built into a lightweight chassis it could probably set a world speed record, but to be a useful locomotive you would need to add lots of ballast. Oh, and they cost $2.2M a pop. And the rated life is 500-600 hours which doesn't sound very helpful!

The rated life does not mean the engine is scrap at that time though obviously! You could feasibly have a pool of engines and have them removed for servicing external to the locomotive, with the locomotive being restored to service with a "spare" from the pool.

Also there are plenty of obvious uses for the excess weight.... for example a traction transformer.
You could have a true Co-Co electrodiesel with great performance on diesel and electric power.

That also means the relatively short running life of the engine becomes less important.

 

[DerekC]

The rated life does not mean the engine is scrap at that time though obviously! You could feasibly have a pool of engines and have them removed for servicing external to the locomotive, with the locomotive being restored to service with a "spare" from the pool.

Also there are plenty of obvious uses for the excess weight.... for example a traction transformer.
You could have a true Co-Co electrodiesel with great performance on diesel and electric power.

That also means the relatively short running life of the engine becomes less important.

A more realistic place to start might be an industrial gas turbine (turboshaft) standby generator set. For example Kawasaki make one with 4.6MW electrical output in a package 7.7m x 3m x 3.6m and weighing 39 tonnes. That sounds like a development kickoff point. However it guzzles 2000 litres an hour of diesel at rated output, which sounds to me like an overall efficiency of about 25% - whereas a diesel cycle set of the same size would have an efficiency typically between 45% and 50%. So I think you could potentially pack more power into a UK locomotive with a turboshaft engine, but the result would be very expensive to own and run - and definitely a major step backwards in terms of carbon emissions!

 

[HSTEd]

A more realistic place to start might be an industrial gas turbine (turboshaft) standby generator set. For example Kawasaki make one with 4.6MW electrical output in a package 7.7m x 3m x 3.6m and weighing 39 tonnes. That sounds like a development kickoff point. However it guzzles 2000 litres an hour of diesel at rated output, which sounds to me like an overall efficiency of about 25% - whereas a diesel cycle set of the same size would have an efficiency typically between 45% and 50%. So I think you could potentially pack more power into a UK locomotive with a turboshaft engine, but the result would be very expensive to own and run - and definitely a major step backwards in terms of carbon emissions!

There are also recuperated gas turbines in this power output range that have ~40% efficiency, which is comparable to modern diesel traction engines.
Like this thing, not clear how much it weighs and this includes a CHP installation on the exhaust which would obviously be deleted, unless there is enough weight to go full blown turbosteamer!

EDIT:
It apparently masses 45 tonnes all up including generator, steam generator and reduction gearing.
The reduction gearing can be deleted obviously because we don't care about the generator frequency.

 

[randyrippley]

Well yes, - so you could install the Rolls-Royce T406 with a maximum power of roughly 4.5MW and a weight of about 500kg - but what do you do with it? if built into a lightweight chassis it could probably set a world speed record, but to be a useful locomotive you would need to add lots of ballast. Oh, and they cost $2.2M a pop. And the rated life is 500-600 hours which doesn't sound very helpful!

Except you would use a maritime or power station version of the engine such as the MT7 - much longer life

 

[DerekC]

Except you would use a maritime or power station version of the engine such as the MT7 - much longer life

Yes - see post #20.

I am tempted to ask what we want this very high powered UK locomotive for. I know it's the "Speculative Ideas" area so anything goes, but knowing the target does provide focus. Presumably freight. Longer Class 4 trains don't really work because of loop lengths, so maybe longer Class 6 stone trains? Also maybe there are places where more power could maintain Class 4 speed at 75mph up a long gradient, but the most obvious ones are on WCML and electrified.