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Foden

Difference in performance of class 31 & 37

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I’m wondering if drivers noticed much difference in the performance characteristics between ‘standard’ 37s and 31s, which of course had the same engine (albeit non intercooled I believe?)?

 

I’m aware of course that 31s were A1A configuration, so I imagine traction was less with the 31, and I also know that 31/4 had issues regarding ETH power never being available for traction regardless of whether ETH was being used.

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The anecdotal line is the 31 could not pull the skin off a rice pudding and if the eth version more than 4 and if you turned on the heating speed would fall - however had good runs on short trains on the Western and on trains in Wales .

 

The 37 however is a powerhouse in some eyes completely unstoppable , I knew a driver charging snow drifts had the snow over the bonnet and then over the roof - power wide open and busting into sunshine at Forsinard - to find the home signal at danger, no Spad as signalman cleared it in the face of the snowball approaching the station !   Equally had great runs on the Cambrian back in the day.

 

But as other say "other versions are available."

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I once asked an Old Oak Common driver what he thought of Class 31s.  His reply was "a hundred tons of useless f****** s***".  I gather that was a quite widely held view. 

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28 minutes ago, DY444 said:

I once asked an Old Oak Common driver what he thought of Class 31s.  His reply was "a hundred tons of useless f****** s***".  I gather that was a quite widely held view. 

Pretty accurate in my experience of the things.  They occasionally turned up on the 07.15 Oxford - two in multi vice the bookedType 4 power.  My experience of them, as am mu'd pair, is readily summed up - even if they were opened up they still couldn't get up to 85mph approaching the 85 board at Acton Main Line whereas with the booked loco you had to shut off in good time in order to lose the speed to drop down to 85.   Coach pilot was just about their limit.  When they had been offered for the Cranmore brancxh in slightly earlier years they couldn't even take as many loaded tank cars up the branch as a Class 25 (which could manage 3 - yes, three - on a good day).

 

In contrast 37s could pull the side off a house although with really heavy trains their speed tended to drop off somewhat but they could manage well over 1,000 tons trailing load through the Severn Tunnel (rather slowly once the whole train was on the rising gradient).

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On the Eastern Region (Doncaster)  31s worked as pairs on most coal trains made up of 16T minerals wagons,  two ponies to do the work of a horse!

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31's were, strictly speaking, only Type 2's, so it is little unfair to make comparison with a top-end Type 3. More relevant is comparison with other Type 2's, such as the Class 24's, 25's and 26's.

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Thanks for the replies guys.

 

See it’s this apparent huge difference in performance that’s so surprising. On paper the 31 is ‘only’ just short of 300hp down on the 37, indeed two 31s with not far off 3000hp is circa 500hp up on a single 47, yet opinions suggest a single 47 would run rings round a pair of Peds in terms of performance.

 

So it leads me to believe its not all in the figures on paper. It can’t be about tractive effort as itv seems getting a train moving isn’t the issue, it’s getting it up to, and keeping speed with a load on.

 

So where does the poor ol 31 go wrong?

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A pair of 31s were pretty reasonable they were quite common on humberside oil trains and also on boulby trains.

I used to quite like them , I remember working a charter to whitby with one about 92 and having to turn the heat off going up nunthorpe bank as I don't think it would have pulled away from the crossing at gypsy lane

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31s are 100 plus tons  for a type 2 but a 26/ 27 around 70 tons  so the 31 has to lug more around so it is going to be poorer , it is just a statement of the times in which it was planned where steam engine designers were getting to hand with diesels. compare the D600 to D800 for how stressed light weight bodies came to the fore. 

Robert      

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It's not really like for like, as the traction motors were different and the prime movers, even when the 31s were given the same units as the 37s, were rated differently.  My experience is of riding on them as a guard in the 70s, and both classes had their strengths and weaknesses.  The 31 had one of the nicest cabs to ride in, good visibility, and a smooth ride, and not too draughty if the cab front doors had been welded up, but they didn't seem to be any better than a 25 in any other respect. We had 25s and 31s at Canton to replace Hymeks, but a Hymek could outperform both of those even if they'd been coupled together.

 

37s were a bit rough and ready, poor visibility, noisy cab, everything shook and rattled, but they couldn't 'arf go!  They couldn't arf pull as well!  A Hymek in good condition was still a coach better, though, because of the 75ton-105ton weight difference.  This is a clue to the lack of performance of 31s in multiple; high end type 4 power in locos weighing 216 tons in all.  Class 40s were a bit pedestrian at 142 tons for 2.000hp, but were probably a better bet than this!  Canton men couldn't understand the thinking behind a loco the size and weight of a 52 with such an inferior power rating and tractive effort in comparison.

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1 hour ago, Foden said:

Thanks for the replies guys.

 

See it’s this apparent huge difference in performance that’s so surprising. On paper the 31 is ‘only’ just short of 300hp down on the 37, indeed two 31s with not far off 3000hp is circa 500hp up on a single 47, yet opinions suggest a single 47 would run rings round a pair of Peds in terms of performance.

 

So it leads me to believe its not all in the figures on paper. It can’t be about tractive effort as itv seems getting a train moving isn’t the issue, it’s getting it up to, and keeping speed with a load on.

 

So where does the poor ol 31 go wrong?

 

You've got to look at traction motor horsepower as well, and not just engine horsepower. As a 31 only has 4, so it gives away roughly 33% when compared to the 37 straightaway. It actually has the same traction motors as the class 46s, they were 2500 engine horsepower.

There are then the other differences, like wheel diameter, gearing, field diversion settings, etc.

They were well suited to ECS OC - Padd, and were staple Acton - Chinnor on coal for the cement works for years....

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I’m amazed anyone thought a 31 cab was nice. I was used to riding in 33 and 73 while out on engineering jobs, and the one and only time we had a 31 and I went up to talk the job through with the driver I was gobsmacked by how utterly crude it all seemed, and I don’t think there was a fraught screen, although I may have that wrong.

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I am sure all this is true and that they were not good on medium to heavy freights, but remember the 31's worked the Kings Cross outer suburbans (and many of the Liverpool Street workings) for a couple of decades or more, without serious calamity (ok, the odd failure). And that was with the steep incline out of the Hotel Curve, for part of that time. The drag of six or eight bogies on, seems to have been their metier. Perhaps Finsbury Park and Stratford knew how to get the best out of them? Or was it the white roofs??

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18 minutes ago, Nearholmer said:

I’m amazed anyone thought a 31 cab was nice. I was used to riding in 33 and 73 while out on engineering jobs, and the one and only time we had a 31 and I went up to talk the job through with the driver I was gobsmacked by how utterly crude it all seemed, and I don’t think there was a fraught screen, although I may have that wrong.

 

They aren't bad with the exception of the gangway visibility was pretty good and if they weren't too draughty warm in winter and cool in summer with four opening windows

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22 minutes ago, Nearholmer said:

I’m amazed anyone thought a 31 cab was nice. I was used to riding in 33 and 73 while out on engineering jobs, and the one and only time we had a 31 and I went up to talk the job through with the driver I was gobsmacked by how utterly crude it all seemed, and I don’t think there was a fraught screen, although I may have that wrong.

 

They were basic, that's for sure. But I remember riding on one, as a young teen, from Padd to Taunton, on a night run (paper train) in deep winter and thick fog, sitting on a milk crate in the middle (my brother was second man). It was warm and cosy, to say the least.....

 

The journey back, the milk train, was in a Hymek - rather different.

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I worked on both 31's, out of Kings Cross, and 37's, both out of Liverpool Street and later on at Hereford, including the heavyweights and 37/9's. Both were good locos, and in the main didn't give much trouble if looked after properly. Both Finsbury Park and Stratford knew how to maintain class 31's, and I never had trouble with 31's maintained by those depots, and some gave some outstanding performances. I had a couple of failures with 31's from other depots and ER men used to dread getting a WR class 3, which had a very bad reputation. In terms of shifting heavy trains though the Class 37 had the edge, not only in the extra HP, but in the fact that they had two extra driven axles. In later years the ones I worked on where generally Canton based and could be relied upon to get you there, but in general I can't say from experiance either loco was bad. In the end it was down to how well they were maintained.

 

Paul J.

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4 hours ago, Swindon 123 said:

Canton based and could be relied upon to get you there,

You wouldn't have said that about Canton's 116 dmus in the summer of '76, unless by 'there' you meant stuck somewhere.  Dmu maintenance was a heroic failure, glorious defeat, the depot did it's best but was just plain overwhelmed by coolant failures...

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8 hours ago, The Johnster said:

You wouldn't have said that about Canton's 116 dmus in the summer of '76, unless by 'there' you meant stuck somewhere.  Dmu maintenance was a heroic failure, glorious defeat, the depot did it's best but was just plain overwhelmed by coolant failures...

To true The Johnster. By the time I was working at Hereford from the mid 80's, that could be said about any DMU maintained by Canton. I had quite a few failures with Canton based DMU's of all types. Mind you Bristol based ones weren't much better, the B9xx sets being considered right dogs by Hereford drivers.

 

Paul J.

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15 hours ago, Mike Storey said:

I am sure all this is true and that they were not good on medium to heavy freights, but remember the 31's worked the Kings Cross outer suburbans (and many of the Liverpool Street workings) for a couple of decades or more, without serious calamity (ok, the odd failure). And that was with the steep incline out of the Hotel Curve, for part of that time. The drag of six or eight bogies on, seems to have been their metier. Perhaps Finsbury Park and Stratford knew how to get the best out of them? Or was it the white roofs??

 

My first work location on BR, Harlow Town, was served by some of the Cambridge/Liverpool St loco-hauled services, worked by Classes 31 and 37. My recollection is that the 31 could get up to a decent speed (as far as as was possible on that route) but it took an awfully long time ! The 37s on the other hand were just magnificent.

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17 hours ago, Mike Storey said:

I am sure all this is true and that they were not good on medium to heavy freights, but remember the 31's worked the Kings Cross outer suburbans (and many of the Liverpool Street workings) for a couple of decades or more, without serious calamity (ok, the odd failure). And that was with the steep incline out of the Hotel Curve, for part of that time. The drag of six or eight bogies on, seems to have been their metier. Perhaps Finsbury Park and Stratford knew how to get the best out of them? Or was it the white roofs??

Very much down to the type of work I think Mike.  On Western outer suburban services they were lugging around trains of 9 or 10 gangwayed Mk1s with a need to run at speed to maintain time and an ability to accelerate in the upper speed ranges (60+mph) from signal checks.  While they had the horsepower when working in pairs on jobs like that (and they rode quite well) their performance simply wasn't suited to that sort of work, and I rode on them regularly when they were standing in for Type 4s.

 

On the Cranmore branch they were up against some very steep gradients after the Merehead Quarry arrival lines were put in and they simply hadn't got the poke to get any sort of loaded train up the bank beyond Merehead Quarry Jcn - and neither had the 25s, hence the job invariably finished up in the hands of a Type 4 (usually of the 45/46 variety although 1000s could manage it equally well - and did so on one occasion with a 12 coach excursion).

 

So overall very much horses for courses

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Class 31s lingered on long after the other Type 2s so they couldn't have been all bad. 

 

Steven B

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They were big b*ggers with plenty of spare room on board, so fitting air brakes, eth, and airco gear was never a problem.  When refurbished, they were reliable and the very smooth delivery of power to the rail, a feature of the Brush type 4s as well, meant that they were favoured for Royal Train duty.  108 tons on 6 axles gives wide route availability, and where loads were not onerous or gradients severe they were adequate.  We have commented on this thread about their lack of poke, but they were tolerant of being thrashed, even if it didn't always achieve the desired result.  And for all their shortcomings, they were probably the best of the Type 2s, certainly a quantum improvement on the awful class 25s.  So, no, they weren't all bad, but they weren't all that good, either...

 

Mike Stationmaster's comment about horses for courses is very much on the mark.  But, with the benefit of the 20/20 hindsight that this century affords us of the 1955 plan diesels, it is fairly clear that none of the type 1s or 2s were much use, some were complete dogs, and far too many were ordered and built.  IMHO the minimum requirement for a main line diesel loco should have been 1,500hp, and the Brush Type 2s were not far off this in their original form, but in 1955 there was a valid case to be made for lower power locos to replace class 2 or 3 steam.  Their work had all but vanished within a decade, the little that was left being capable of being handled by 08s, and that was not foreseen in 1955, or reacted to for some time afterwards, and the standard in the US, which is what the 1955 was very much 'informed' by, was a 1,200hp loco which you could use in mulitples of A units with cabs and cabless B 'slave' units, all gangway connected, to pull anything, backed up by 800hp road switchers.

 

This appeared to work fine Stateside, where there were few axle load restrictions, and longer loops and sidings, but our railway needed lighter axle loads and as little double heading as possible to efficiently use our loops and sidings, typically limited to 60 standard wagon lengths or 20 coaches.  How well it actually worked over there may be considered in the light of the massive collapse of their railway industry in the face of internal air traffic for passengers and big truck road haulage on Interstate highways, but their geography is different to ours and it's not comparing like for like.  

 

The failings of the 1955 Plan have been discussed to death many times; my apologies if my comments have inadvertently re-opened the matter.

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Pig ugly though (most things designed around gangway connections weren't lookers; EE locos with a "nose" got away with it). The Class 33s are quite pretty by comparison with the 31s.

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5 hours ago, Steven B said:

Class 31s lingered on long after the other Type 2s so they couldn't have been all bad. 

 

Steven B

I think the reason for them lingering was that they had been given English Electric engines (and there emerged a strong preference for EE power over Sulzer in the BRB)  plus they didn't suffer the inherent design faults of the Derby/Sulzer Type 2 (Classes 24 & 25) which were never entirely solved even with the progressive batches of the Class 25 version.

 

The original Mirrlees engines in the Brush Type 2 clearly fell out of favour for some reason hence them being re-engined with the 1.470 hp EE engine.

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