The effect of ETH-AirCon on locomotive performance, with an emphasis on classes 33, 47/4, 50 and 52.

[70014IronDuke]

There's been reference to the greater installed horsepower of 47s over 40s and the advantage of the former in also having ETH; but didn't ETH reduce the drawbar horsepower available?

mods note - split from this thread:

Why was the Class 45 kept in service over the Class 40?

A straightforward question: As a very junior spotter (accompanied by a very knowledgeable uncle, now unfortunately deceased) in the early 80s, a frequent trip was from Warrington BQ up to York to the National Rail Museum (and the Jorvik Viking Centre). As I recall, 45s and occasionally 40s...

www.railforums.co.uk

Yes. But it would do that when installed to both classes, of course (dependent on the power output of the ETH alternator).

Any ideas of a likely value - you just need to know the kw of an electric heated train and convert to power in terms of hp.

The number 400 hp came to mind initially, but that seems far too much considering a Cl 47 was only 2,580 (?) hp in total. Even for a 12-coach train of air-con stock. (It's all of 50 years ago now.)

I never understood the enthusiasm for EE4s; when they replaced steam on the West Coast their shortcomings were immediately apparent. I spotted at Roade where there was I think a 1 in 300 climb from the South. Watching, first, a Pacific romp effortlessly (ok, the fireman was puttiing in some effort!) past on 16 by followed by an EE4 on 11, full power thrashing away and grinding past at half the speed. Initially, the EE4s only took over 6P and 7P steam diagrams, the 8P ones were beyond them. The 8P trains loaded to 16; the solution - cram everyone into 11 cars so the EE4s could take over and scrap the Pacifics at a stroke.

Is this factually true, or just what you deduced?
I certainly remember long trains of 15 or so on the WCML - but they seemed to lumber along at around 55-60 mph whatever loco was at the front.
And did they really just cut the loads to 11? I never knew when or how the long trains just disappeared.

I also had an excruciating run behind an EE4 on the down Royal Scot in January 1963; boiler out of action, so as well as the coaches the EE4 had to lug a Black 5 for steam heat. Max speed about 50 mph on the downhill sections.
The loco handbrakes on EE4s also seemed a bit sketchy; when stabled they had to be scotched presumably as a result of experience.

 

[hexagon789]

The number 400 hp came to mind initially, but that seems far too much considering a Cl 47 was only 2,580 (?) hp in total. Even for a 12-coach train of air-con stock. (It's all of 50 years ago now.)

Class 47/4 ETH index is 66, which is 330kW or 442.5hp.

 

[Harpo]

Class 47/4 ETH index is 66, which is 330kW or 442.5hp.

Which is, of course, a maximum figure.

As that’s tapped straight from the alternator/generator, I’d guess that the hp lost at the rail would be less than that?

 

[edwin_m]

Which is, of course, a maximum figure.

As that’s tapped straight from the alternator/generator, I’d guess that the hp lost at the rail would be less than that?

Maybe, but wouldn't the effective loss in engine power be more?

 

[70014IronDuke]

Class 47/4 ETH index is 66, which is 330kW or 442.5hp.

Ah, so the old memory box is not so bad, after all!

Which is, of course, a maximum figure.

Maximum rated for the 47/4, yes.

As that’s tapped straight from the alternator/generator, I’d guess that the hp lost at the rail would be less than that?

No. The ETH load would have - does - come off the total power output. (well, I'm not sure about modern traction.)

EDIT: Ah, on second thoughts, I suppose what you mean is that if the (say, 400 hp) ETH load had gone via the traction motors to the rail, it would have involved transmission losses, and so would come out at (say) 300 hp at the rail. Yes, fair point.

However, that would assume constant ratio of transmission losses. In practice, I suspect this would depend on the characteristics of the traction motors, which would likely not be linear vis-a-vis the power delivered. So the answer is, I don't know.

If I remember correctly, both the 45/1s and 47/4s had a button to switch off the ETH load for approx 30 seconds if the driver wanted to use maximum power to keep/regain time. The carriage motor alternators would then switch back on at slightly different intervals within the next 30 seconds to avoid a sudden increase in load on the auxiliary (ETH) alternator. Whether they kept this facility to the end of their lives or not I don't know.

 

[hexagon789]

Which is, of course, a maximum figure.

Indeed, but would be equivalent to about 13 air-con coaches so not an impossible load.

As that’s tapped straight from the alternator/generator, I’d guess that the hp lost at the rail would be less than that?

Assuming a lesser ETH load then yes, but something like The Clansman for example loaded to 12/13/14 vehicles in the late-70s to early-80s and other than the restaurant car and full brake were all air-con vehicles post-1976.

Ah, so the old memory box is not so bad, after all!

Indeed! I personally had to double check as I couldn't recall if the index was 60 or 66

If I remember correctly, both the 45/1s and 47/4s had a button to switch off the ETH load for approx 30 seconds if the driver wanted to use maximum power to keep/regain time. The carriage motor alternators would then switch back on at slightly different intervals within the next 30 seconds to avoid a sudden increase in load on the auxiliary (ETH) alternator. Whether they kept this facility to the end of their lives or not I don't know.

Not sure about 45s, but 47s had a button on the end of the power handle to do this IIRC. It's detailed somewhere in a book I have on the Class.

 

[AndrewE]

Indeed, but would be equivalent to about 13 air-con coaches so not an impossible load.

Assuming a lesser ETH load then yes, but something like The Clansman for example loaded to 12/13/14 vehicles in the late-70s to early-80s and other than the restaurant car and full brake were all air-con vehicles post-1976.

Indeed! I personally had to double check as I couldn't recall if the index was 60 or 66

Not sure about 45s, but 47s had a button on the end of the power handle to do this IIRC. It's detailed somewhere in a book I have on the Class.

did WCML electric locos have this facility too? Some coaching stock circuits were marked "1000 Amp wiring" because the kitchen car was all-electric, and I have a vague memory of on-board staff complaining the the kitchen lost power if the driver felt he needed it all!

 

[hexagon789]

did WCML electric locos have this facility too? Some coaching stock circuits were marked "1000 Amp wiring" because the kitchen car was all-electric, and I have a vague memory of on-board staff complaining the the kitchen lost power if the driver felt he needed it all!

There would be no need on an electric loco, the ETH supply doesn't affect the traction output. More likely:

1. Crew forgot to switch on the ETH
2. A fault or improperly connected jumper
3. Passage of a neutral section

 

[AndrewE]

There would be no need on an electric loco, the ETH supply doesn't affect the traction output. More likely:

1. Crew forgot to switch on the ETH
2. A fault or improperly connected jumper
3. Passage of a neutral section

so a loss of 1000A (at 450V) is inconsequential?

I'm sure neither 1 or 2 would have been the case as the restaurant staff would have been up to the front at the first stop! And passing a neutral section must only have taken second or two...

Maybe I am mis-remembering and it was from rides from Bristol on the NE-SW services.

 

[Merle Haggard]

Yes. But it would do that when installed to both classes, of course (dependent on the power output of the ETH alternator).

I accept that, but my post was with regard to another up thread which compared steam heat 40s with ETH 47 . Interesting that your estimates suggest that an ETH 47 would only have a slight edge over a steam heat 40; and the actual later power settings of a class 47 are not clear.

Is this factually true, or just what you deduced?
I certainly remember long trains of 15 or so on the WCML - but they seemed to lumber along at around 55-60 mph whatever loco was at the front.
And did they really just cut the loads to 11? I never knew when or how the long trains just disappeared.

It was factual (about Cl 8 train loads having being reduced for dieselisation) based on what I had read. I will have to find it, which might take some time, but my recollection was that it was from a credible 'inside' source - Alec Swain I think. It might have been in The 'The Book of ...). I do usually condition my statements that rely on assumptions - and sometimes the mods jump on one for sources if you don't.

Probably connected with the mass withdrawal of the remaining Pacific at the end of the Summer 1964 timetable, some not long out of Works.

I saw a lot of West Coast trains in the early 1960s but didn't travel on them much (fares were high then!). However, it's worth pointing out that, certainly at the South end, the schedules included large lumps of engineering allowances (for electrification) and if these weren't actually needed the better choice seemed to be to run slowly. There was a remark in a Trains Illustrated once of a correspondent who was on an Up train that waited time for half an hour at Watford Junction, presumably the result of the driver not easing in those circumstances.

Cutting off the ETH to give more drawbar power had the steam ecquivalent ion closing the steam heat valve on a steam loco; I think a driver was quoted by W. A. Tuplin as saying 'just switch it back on for the last half hour - they (the passengers) will forget that were cold at the start'.

 

[hexagon789]

so a loss of 1000A (at 450V) is inconsequential?

I'm sure neither 1 or 2 would have been the case as the restaurant staff would have been up to the front at the first stop! And passing a neutral section must only have taken second or two...

Maybe I am mis-remembering and it was from rides from Bristol on the NE-SW services.

I've never heard that ETH affected the power output of electrics only diesels. Electrics can draw a greater eletrical load from the overhead but diesels are limited by the power of their engines?

 

[Merle Haggard]

I've never heard that ETH affected the power output of electrics only diesels. Electrics can draw a greater eletrical load from the overhead but diesels are limited by the power of their engines?

On the AC lines loco transformer fires when hauling passenger trains are not unknown. Presumably the ETH load as well as then traction load passes rough the transformer. Just a suggestion - I don't know if the cause of fires was transformer overload or damage due to some other cause.

 

[hexagon789]

On the AC lines loco transformer fires when hauling passenger trains are not unknown. Presumably the ETH load as well as then traction load passes rough the transformer. Just a suggestion - I don't know if the cause of fires was transformer overload or damage due to some other cause.

Certainly I could understand that drawing a large electrical load could overload things, create a fire potential, sure.

It was more that the ETH load is seperate to the traction load - the locomotive will have a maximum ETH load and within that the locomotive's maximum the locomotive's rated traction power should still be available.

An 87 would still produce 5,000hp in weak field with a full ETH load, whereas a 47 would produce an at-rail figure of considerably less than its quoted continuous output with a full ETH load, as would any diesel. That was what I was trying to say.

(I do sometimes think I'm terrible at explaining my meaning succinctly, sorry)

 

[Magdalia]

Class 47/4 ETH index is 66, which is 330kW or 442.5hp.

Class 45/1 and class 47/4 were ETH 66, both had a Brush dual wound alternator which powered the ETH and the auxiliary equipment.

Indeed, but would be equivalent to about 13 air-con coaches so not an impossible load.

Coaches also had an ETH rating. Most Mark II aircon vehicles were ETH 4, so the maximum ETH load for a loco with ETH 66 was 16 coaches.

In practice few trains exceeded 12 coaches

 

[hexagon789]

Coaches also had an ETH rating. Most Mark II aircon vehicles were ETH 4, so the maximum ETH load for a loco with ETH 66 was 16 coaches.

My mistake, I was thinking index 5 for Mk2 ACs, though Mk3 sleepers were higher, I believe index of 6-7 depending on type.

 

[Taunton]

If I remember correctly, both the 45/1s and 47/4s had a button to switch off the ETH load for approx 30 seconds if the driver wanted to use maximum power to keep/regain time. The carriage motor alternators would then switch back on at slightly different intervals within the next 30 seconds to avoid a sudden increase in load on the auxiliary (ETH) alternator. Whether they kept this facility to the end of their lives or not I don't know.

The experts at this were the drivers on Waterloo to Exeter in the 1970s, particularly west of Salisbury. The 2,200hp Warships (plus steam boiler) were replaced by 1,550hp Class 33, including ETH. No little button, they just switched the ETH on and off. On approaching and stopped at a station, then off and full power to accelerate away, or up a bank. Over the top, controller back, heat on again.

Class 27 on the Edinburgh-Glasgow push-pull drove fairly full power for much of the time on that run, so had separate Deutz ETH auxiliary diesels installed in Class 27/2. These were a considerable trial for all, noisier than the main engine, tended to overheat, or at worst catch fire. Operating remotely in the rear loco, this rapidly brought about additional fire warnings and automatic CO2 extinguishers, which had unreliability of their own. Nothing is simple.

 

[Richard Scott]

Though, as I understand it while the refurbished 37s with an alternator can be immediately opened to full power, unrefurbished ones could be easily overloaded at low speeds, so initial acceleration is probably better on refurbished examples?

47s can be opened to full power straightaway with the only potential issue being rail conditions, the locos themselves can take it.

Not quite that simple, the EE engine revs up much quicker than a Sulzer so more likely to overload due to line speed being low once maximum engine power being produced. The Sulzer takes quite a while to reach maximum output especially due to having one large turbo so significant turbo lag. By the time the Sulzer is producing maximum power line speed has increased to a level that the generator is unlikely to be overloaded even if you open power handle to maximum from a standing start. Sulzer engine also limits how much fuel is injected if turbo at low boost.

To be fair to Brush it was the Sulzer engine that was the "problem". Though BR did actually discover what could be done to improve the reliability of the block (when uprated to give 2750BHP) but by then decided it was not worth yet another modification and the downrating may well still help long term reliability.

Brush electrics were still inferior to Crompton Parkinson, though. This is mostly why the older 45s outlasted the younger 46s.

 

[70014IronDuke]

The experts at this were the drivers on Waterloo to Exeter in the 1970s, particularly west of Salisbury. The 2,200hp Warships (plus steam boiler) were replaced by 1,550hp Class 33, including ETH. No little button, they just switched the ETH on and off. On approaching and stopped at a station, then off and full power to accelerate away, or up a bank. Over the top, controller back, heat on again.
...

Fascinating initiative by the SW drivers - or was it actually officially encouraged from higher up? I rather suspect that drivers were rather frustrated by the reduced power of the Cl 33s being diagrammed for those trains - not that the 33s were not good locos, just that they were not really designed for such services, certainly for the timings elsewhere in the 1970s.

I can imagine some old hands would be saying "We could do better with an Arthur!".

I accept that, but my post was with regard to another up thread which compared steam heat 40s with ETH 47 . Interesting that your estimates suggest that an ETH 47 would only have a slight edge over a steam heat 40;

Indeed. This is why my second reaction to my own figure of 400 hp which flashed into my mind was: Hmm, that seems an awful lot (as a percentage of total power).

In view of that, I find it remarkable that the advent of ETH power loss on trains did not produce complaints about extended schedules vs earlier steam heat versions. At least, I can't remember any such talk.

For example, I have a memory that @Senex wrote at some point in the past that non-stop St Pancras - Leicester timings were extended from 82 minutes to 82 1/2 minutes in the working TT when air-con was introduced. This seems a miniscule addition considering the relative ETH load - although these trains were only 9 coaches, as I remember. (and possibly even cut to 8 because of ETH?). Apologies in advance if I've misremembered anything here.

But thinking about the Swansea - Pad trains, these were normally 11 coaches, so a significantly heavier ETH load, and one that would leave a 47/4 theoretically well under power compared to a Cl 52 on steam-heat stock. (Sorry, drifting further off topic here, at least the Cl 40 bit.)

and the actual later power settings of a class 47 are not clear.

Is that so?

It was factual (about Cl 8 train loads having being reduced for dieselisation) based on what I had read. I will have to find it, which might take some time, but my recollection was that it was from a credible 'inside' source - Alec Swain I think. It might have been in The 'The Book of ...). I do usually condition my statements that rely on assumptions - and sometimes the mods jump on one for sources if you don't.

OK, thanks. Makes sense

Probably connected with the mass withdrawal of the remaining Pacific at the end of the Summer 1964 timetable, some not long out of Works.

Maybe. I just have a 'feeling' that the heavy loads - 15-6 carriage trains - disappeared by 1963. But I didn't take notes.

I saw a lot of West Coast trains in the early 1960s but didn't travel on them much (fares were high then!). However, it's worth pointing out that, certainly at the South end, the schedules included large lumps of engineering allowances (for electrification) and if these weren't actually needed the better choice seemed to be to run slowly. There was a remark in a Trains Illustrated once of a correspondent who was on an Up train that waited time for half an hour at Watford Junction, presumably the result of the driver not easing in those circumstances.

Yes. I do remember reading reports in MR about this, though I thought it was more common in later years, ie 1965-6, just prior to the inauguration of the new electric schedules.

Cutting off the ETH to give more drawbar power had the steam ecquivalent ion closing the steam heat valve on a steam loco; I think a driver was quoted by W. A. Tuplin as saying 'just switch it back on for the last half hour - they (the passengers) will forget that were cold at the start'.

Ha ha! It's an interesting point - how much did drivers use this facility in normal working with steam. I can't ever remember seeing any mention of this in performance reports - but perhaps as a kid-teenager I was just ignorant of it and therefore it merely passed me by.

Must have been tempting option when running late over Shap, Beattock or Ais Gill one might have thought - except that's exactly where heat was needed in winter

 

[Magdalia]

My mistake, I was thinking index 5 for Mk2 ACs

Apologies, the mistake is mine not yours, I can't read my sources properly! Aircon MarkIIs are mostly ETH 5, it is the fresh air MarkIIs that are mostly ETH4.

The 2,200hp Warships (plus steam boiler) were replaced by 1,550hp Class 33, including ETH.

the Cl 33s being diagrammed for those trains - not that the 33s were not good locos, just that they were not really designed for such services, certainly for the timings elsewhere in the 1970s.

There are two important things to remember about the class 33 era on the Waterloo-Exeter trains. First they were not aircon, and second they were booked load 9 in the summer but only load 8 in the winter to compensate for ETH.

In view of that, I find it remarkable that the advent of ETH power loss on trains did not produce complaints about extended schedules vs earlier steam heat versions. At least, I can't remember any such talk.

More generally the introduction of ETH does seem to coincide with a reduction in train lengths, though I don't know that there is anything definitive that demonstrates cause and effect. On the East Coast Main Line it helped that the Peterborough remodelling in 1973 removed the 20 mph speed limit through the station, knocking a big chunk out of schedules just as ETH was coming in.

 

[Merle Haggard]

Fascinating initiative by the SW drivers - or was it actually officially encouraged from higher up? I rather suspect that drivers were rather frustrated by the reduced power of the Cl 33s being diagrammed for those trains - not that the 33s were not good locos, just that they were not really designed for such services, certainly for the timings elsewhere in the 1970s.

I can imagine some old hands would be saying "We could do better with an Arthur!".


Indeed. This is why my second reaction to my own figure of 400 hp which flashed into my mind was: Hmm, that seems an awful lot (as a percentage of total power).

In view of that, I find it remarkable that the advent of ETH power loss on trains did not produce complaints about extended schedules vs earlier steam heat versions. At least, I can't remember any such talk.

For example, I have a memory that @Senex wrote at some point in the past that non-stop St Pancras - Leicester timings were extended from 82 minutes to 82 1/2 minutes in the working TT when air-con was introduced. This seems a miniscule addition considering the relative ETH load - although these trains were only 9 coaches, as I remember. (and possibly even cut to 8 because of ETH?). Apologies in advance if I've misremembered anything here.

But thinking about the Swansea - Pad trains, these were normally 11 coaches, so a significantly heavier ETH load, and one that would leave a 47/4 theoretically well under power compared to a Cl 52 on steam-heat stock. (Sorry, drifting further off topic here, at least the Cl 40 bit.)


Is that so?


OK, thanks. Makes sense


Maybe. I just have a 'feeling' that the heavy loads - 15-6 carriage trains - disappeared by 1963. But I didn't take notes.


Yes. I do remember reading reports in MR about this, though I thought it was more common in later years, ie 1965-6, just prior to the inauguration of the new electric schedules.


Ha ha! It's an interesting point - how much did drivers use this facility in normal working with steam. I can't ever remember seeing any mention of this in performance reports - but perhaps as a kid-teenager I was just ignorant of it and therefore it merely passed me by.

Must have been tempting option when running late over Shap, Beattock or Ais Gill one might have thought - except that's exactly where heat was needed in winter

Thanks for all the responses.

Regarding my comment about the power settings on 47s - that dates from my RfD days. A colleague in the Production department spent some of his time rounding up redundant 47s from other sectors and remarked about the differences between allegedly standard locos. I also recollect, perhaps imperfectly, a remark by the RfD Director, M&EE. All to the effect that there'd been lot of de-rating and restoration, not always uniformly . Making an (I think) E3 1 1 enquiry seemed to support this, although after nearly 30 years I'm not certain. That enquiry certainly showed other detail differences between individual locos within even a sub-class - e.g. for fuel capacity (long-range ones) suggesting that the records were accurately loco specific.

 

[Richard Scott]

But thinking about the Swansea - Pad trains, these were normally 11 coaches, so a significantly heavier ETH load, and one that would leave a 47/4 theoretically well under power compared to a Cl 52 on steam-heat stock. (Sorry, drifting further off topic here, at least the Cl 40 bit.)

Hence why 40GTis i.e. the class 50s were brought in. Much better power spread than the 47 and the Western's poor matching of transmissions with engines meant a 50, even with ETH on, was equal to a Western.

 

[70014IronDuke]

Hence why 40GTis i.e. the class 50s were brought in. Much better power spread than the 47 and the Western's poor matching of transmissions with engines meant a 50, even with ETH on, was equal to a Western.

Except that 50s never worked the Swanseas, surely? 50s worked the WoEs and Bristols (at least when first sent to the WR.) I thought the Swanseas went straight from 47/4s to HSTs. In any case, they started off AirCon (in 73?) with 47/4s.

 

[Harpo]

Except that 50s never worked the Swanseas, surely? 50s worked the WoEs and Bristols (at least when first sent to the WR.) I thought the Swanseas went straight from 47/4s to HSTs.

Yes. 50s weren’t booked to Padd- Swanseas but appeared on Padd-Cardiff reliefs in the early 80s and appeared ad-hoc vice HST on the 0700 Padd-Cardiff & 09.xx back at the end of the 80s.

No South Wales depot ever became 50-trained. Canton started learning but the programme was never completed and their booked jobs were (mostly) covered by 45/1s.

 

[Richard Scott]

Except that 50s never worked the Swanseas, surely? 50s worked the WoEs and Bristols (at least when first sent to the WR.) I thought the Swanseas went straight from 47/4s to HSTs. In any case, they started off AirCon (in 73?) with 47/4s.

Ah OK, fair point.

 

[Wilts Wanderer]

Hence why 40GTis i.e. the class 50s were brought in. Much better power spread than the 47 and the Western's poor matching of transmissions with engines meant a 50, even with ETH on, was equal to a Western.

I would go further than that - in terms of power at rail, at all but the lowest speeds, a 50 was well ahead of a Western even with the ETH factor. I have a book analysing diesel traction performance and using the high-speed run over Whiteball as a benchmark, it states that a 50 would slightly outperform a 47, whereas with the same load a 52 would barely justify its Type 4 rating, let alone compete with its diesel-electric competitors.

 

[Magdalia]

I would go further than that - in terms of power at rail, at all but the lowest speeds, a 50 was well ahead of a Western even with the ETH factor. I have a book analysing diesel traction performance and using the high-speed run over Whiteball as a benchmark, it states that a 50 would slightly outperform a 47, whereas with the same load a 52 would barely justify its Type 4 rating, let alone compete with its diesel-electric competitors.

I worked with numbers all of my working career. I have also timed trains and competitors in sporting events. I make the following points:

• locomotive performance data from the era we are talking about has a significant amount of measurement error because of the lack of sophistication of the equipment used and the skills of those using that equipment.
• there was considerable variation in performance between different locomotives within the same class, and with the same locomotives over time.
• External factors such as weather and driving technique also impact on performance.

This means that it is impossible to draw any firm conclusions about the relative performance of different classes from a small number of recorded journeys. The differences will be within the margins of statistical error.

 

[Taunton]

... the Western's poor matching of transmissions with engines meant a 50, even with ETH on, was equal to a Western.

This was got to grips with on a number of Class 52 Westerns, the "Golden Westerns", before even the Class 50 came over. It was never apparent to me just what the work done was, or why only a limited number were done. Presumably there was a cost. They were run as a subset on, among others, the Cornish Riviera and the Golden Hind, the fastest Plymouth services.

 

[Harpo]

• there was considerable variation in performance between different locomotives within the same class, and with the same locomotives over time.

Quite. 47s, for example, had those you could get 100mph from and those that you never would. I’ve heard a driver theory of differing electrical series matching that.

• External factors……..driving technique also impact on performance.

I remember a certain lady manager causing incredulity by asking ‘why don’t all drivers drive the same?’

That’s been sorted but feels as if the training was done by the slowest ex-driver of unfitted freight in some places. (Go west young man…..)

 

[Justin Smith]

Indeed. This is why my second reaction to my own figure of 400 hp which flashed into my mind was: Hmm, that seems an awful lot (as a percentage of total power).

In view of that, I find it remarkable that the advent of ETH power loss on trains did not produce complaints about extended schedules vs earlier steam heat versions. At least, I can't remember any such talk.

For example, I have a memory that @Senex wrote at some point in the past that non-stop St Pancras - Leicester timings were extended from 82 minutes to 82 1/2 minutes in the working TT when air-con was introduced. This seems a miniscule addition considering the relative ETH load - although these trains were only 9 coaches, as I remember. (and possibly even cut to 8 because of ETH?). Apologies in advance if I've misremembered anything here.

But surely peak power is not needed from the diesel all the time (e.g. when going down hill, or stopped in a station etc) ? In fact what proportion of the time is peak power actually needed ? Could ETH not be switched off on the climbs ? And if it could one has to question how much actual difference it made to schedules.

 

[Merle Haggard]

I have a recollection that, at the time, it was stated that the Southern Region specified BRC&W locos with a higher power engine (and therefore became Type 3) than the (Type 2) ones ordered by other Regions to provide for ETH - the aim being to provide the same traction power. But I am far from sure - something I think I read about in the early 1960s.