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Why did the 20s outlast other classes?

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9 hours ago, 18B said:

 

perhaps however, it's the conservative rating of the power unit which ment they weren't thrashed, THe Class 20s, 31s, and 37s, outlived the Class 24/25s...

 

The class 37's did have the higher rating, otherwise they would have been 1,500bhp, and they have done just fine.

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English Electric equipment as a whole, not just the engines, was generally conservatively engineered. They understood the railway environment, as well as the sort of staff who would maintain their products - not electricians but ex-steam fitters. The differences in design were clear in the days when GEC Traction were building the different equipments side by side at Trafford Park in the 1970s when I started my railway career.

 

Jim

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5 hours ago, Titan said:

The class 37's did have the higher rating, otherwise they would have been 1,500bhp, and they have done just fine.

The 37s had the CSVT of the 50s, rather than the SVT of the 20s and 40s, but derated to 1,750hp. At full rating, the 37s would have had 2,000hp, or even a little over - apparently English Electric offered this to BR, who weren't interested. EE actually built what was very nearly a Class 20 with the CSVT engine in the Portugese Railways Class 1400 - with 1,330 horsepower on hand. That would show any of the Type 2s who was in charge, except for the Class 31 which was really a Type 3 with an inferiority complex.

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1 hour ago, RLBH said:

The 37s had the CSVT of the 50s, rather than the SVT of the 20s and 40s, but derated to 1,750hp. At full rating, the 37s would have had 2,000hp, or even a little over

 

Who told you that? Source?

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On 31/12/2017 at 16:24, D854_Tiger said:

Why did the 20s outlast other classes

 

 

Perhaps it was their looks.

 

One of my old neighbours used to be a driver at Bescot depot, he told me that an important item of equipment in the winter was a bin liner to wrap around your legs in order to keep out the cold draughts.

 

I never did find out which particular type he was referring to but it was around the time Bescot had a plentiful allocation of class 25s so always assumed it must have been them.

 

We usually  associate the 47 with cab draughts and binliners , was n't there a  a TV documentary about BR with  a driver turning  up for duty  with his supply of binliners to work  a diagram with a 47?

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Posted (edited)

One obvious point,  2 x 20s has an  advantage of  8 powered axles to shift those heavy coal trains on those poorly maintained colliery sidings

Edited by Pandora
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13 minutes ago, Titan said:

 

Who told you that? Source?

Any of the BR diagram books on the Barrowmore MRG website will show that Class 37s had the 12-cylinder version of the CSVT engine. In 16-cylinder form in DP2 and the Class 50s, it gave 2,700hp from 16 cylinders for 168.75 hp/cylinder.

 

The same maths gives you 1,350hp for the 8CSVT; the Portugese Class 1400 actually developed 1,330hp, which is close enough that I'm not going to quibble over it.

 

The 12SVT was fitted in Class 31s, slightly derated to 1,470hp so as not to overload either the electrical or the cooling capacity of the existing locomotive, I'm not entirely clear which.

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10 minutes ago, Pandora said:

One obvious point,  2 x 20s has an  advantage of  8 powered axles to shift those heavy coal trains on those poorly maintained colliery sidings

 

Braking power is more important than hauling power regarding goods traffic.

 

As a train driving pal of mine once said - "any idiot can get a train rolling - it's stopping the that takes the skill!"

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On 26/12/2017 at 12:10, Legend said:

I think it’s the need for constant development and always find something better. The Clayton was perceived to be that better loco mainly because of its central cab that gave improved visibility. And it probably would have been the new standard the 1 .....had it worked! Of course they were chronically unreliable and more Class 20s had to be built to replace them .

When I spoke with a D&E group  member about their preserved Clayton, they had improved their loco by working on fuel flow , lifter pumps  and fuel deiivery pipes of greater diameter and better flow "It starts on the button"  I believe there  were two versions of the Claytondiesel  engine, strong but heavy or lightweight alloy crankcases,  BR rejecting advice and opting for the Alloy versions which  failed all too soon with fractures

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Posted (edited)
16 minutes ago, Holmesfeldian said:

 

Braking power is more important than hauling power regarding goods traffic.

 

As a train driving pal of mine once said - "any idiot can get a train rolling - it's stopping the that takes the skill!"

Agreed,  but  there are a better classes of idiot , they burn the rails with wheelspin, and others who will put flats on the tyres on the trip back  from  a tyre-turning by the wheel- lathe.

On a fitted train,  much of the braking is by the rolling stock and not the locos,  for that reason light loco movements in formation  are subject to reduced maximum speeds 

Edited by Pandora

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2 hours ago, Pandora said:

We usually  associate the 47 with cab draughts and binliners , was n't there a  a TV documentary about BR with  a driver turning  up for duty  with his supply of binliners to work  a diagram with a 47?

If you had a 47 with the buffer beam cowling it would be a draughty journey. The cowling helped duct the draught on to your feet. Footwarmers were poor and the only other heating was bulkhead heaters behind you. 

I piloted a pair of 20s in the 1990s on the sudbury branch. They were not as bad as I thought they would be. A little rough but the sudbury line didn't have cwr all the way. 

Those 20s must have been everywhere 

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11 hours ago, jim.snowdon said:

English Electric equipment as a whole, not just the engines, was generally conservatively engineered. They understood the railway environment, as well as the sort of staff who would maintain their products - not electricians but ex-steam fitters. The differences in design were clear in the days when GEC Traction were building the different equipments side by side at Trafford Park in the 1970s when I started my railway career.

 

Jim

 

Differences in design yes but EE electrical kit generally has a number of weak points not experienced by other electrical suppliers, EEs were particularly sensitive to high power shut offs, as can be seen by MODs fitted to 37s and some 20s (which delay power TM contactor separation) they are also far less tolerant of moisture due to the methods of banding in use, which also makes them particularly prone to dirt ingestion, the plus side is a EE generator can be often "cleaned" back into working use with noxious chemicals but another supplier (brush/CP) if the generator/TM has died then cleaning normally has no effect..... but......in defence of the EE kit this problem was exasperated massively by the fan clutch mod fitted to class 37s....

 

EE Electrics are insanely crude compared with other kit as well...Just ask any fitter who has had to change brushes on an EE motor compared with a Crompton Parkinson motor... but EE kit also was either under rated for the demands on it....or too clever for its own good as previously mentioned....the dreaded KV10

 

 

 

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6 hours ago, RLBH said:

Any of the BR diagram books on the Barrowmore MRG website will show that Class 37s had the 12-cylinder version of the CSVT engine. In 16-cylinder form in DP2 and the Class 50s, it gave 2,700hp from 16 cylinders for 168.75 hp/cylinder.

 

The same maths gives you 1,350hp for the 8CSVT; the Portugese Class 1400 actually developed 1,330hp, which is close enough that I'm not going to quibble over it.

 

The 12SVT was fitted in Class 31s, slightly derated to 1,470hp so as not to overload either the electrical or the cooling capacity of the existing locomotive, I'm not entirely clear which.

 

just wondering what your take on the 600bhp engines fitted to the class 73 is?  They were pretty much half a class 20 engine.

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27 minutes ago, Titan said:

 

just wondering what your take on the 600bhp engines fitted to the class 73 is?  They were pretty much half a class 20 engine.

Yes, there seems to have been a later evolution of the SVT that got 150hp/cylinder rather than the 125hp/cylinder of earlier models. You can see this in the Southern Region DEMUs – the earlier Class 201s and Class 203s have the 500hp 4SRKT, whilst later 205s and 207s had the 600hp version. I suspect that this is the rating that EE was proposing for follow-ons to the Class 40s with 2,400hp.

 

A 12-cylinder version of such an engine would put out 1,800hp or thereabouts, which is similar to the rating of the 12CSVT in a Class 37. It may well be that the electrics were designed for the earlier engine then someone decided to put the CSVT in and derate it, probably for fuel economy reasons. But that's pure speculation.

 

For that matter, you can see the uprating at work with the LMS Twins and the Bulleid diesels. All had 16SVT engines, starting at 1,600hp (100hp/cylinder) but progressing to 1,750hp (110hp/cylinder) and ultimately to the 2,000hp used in the production Class 40s.

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6 hours ago, Pandora said:

When I spoke with a D&E group  member about their preserved Clayton, they had improved their loco by working on fuel flow , lifter pumps  and fuel deiivery pipes of greater diameter and better flow "It starts on the button"  I believe there  were two versions of the Claytondiesel  engine, strong but heavy or lightweight alloy crankcases,  BR rejecting advice and opting for the Alloy versions which  failed all too soon with fractures

 

The last 2 built had Rolls Royce engines and probed to be very reliable but it was too little too late

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While the 12CSVT was rated in the 37s at 1,750 hp the Australians got 2,550 hp out of the power units they put in the 2370 class loco’s 

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Here’s some Class 30 gen showing which locos were updated. The 1600hp machines benefitted from improved oil cooled pistons and were used on special duties on the Eastern Region. The 2000hp machine benefited from charge air cooling.

2DD3DB12-F473-4EFF-8428-DB6E717957AB.jpeg

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On 10/03/2020 at 01:34, RLBH said:

 except for the Class 31 which was really a Type 3 with an inferiority complex.

Except for the fact that Class 31's were Type 2 machines, due to their power ratings. D5835 was the only Type 3.

 

The overflow into the 30 series of class numbers, has fooled a lot of people over the years.

 

https://en.wikipedia.org/wiki/List_of_British_Rail_power_classifications#Type_2

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5 hours ago, kevinlms said:

Except for the fact that Class 31's were Type 2 machines, due to their power ratings. D5835 was the only Type 3.

 

The overflow into the 30 series of class numbers, has fooled a lot of people over the years.

 

https://en.wikipedia.org/wiki/List_of_British_Rail_power_classifications#Type_2

 

Surely the 1660 hp machines were tyoe 3s and D5835 was a type 4 - the only BR type 4 with only 4 traction motors? Asking a lot of electrical systems .... and the antithesis to the explanation behind the OP's original question!

 

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

 

 

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7 hours ago, kevinlms said:

Except for the fact that Class 31's were Type 2 machines, due to their power ratings. D5835 was the only Type 3.

 

The overflow into the 30 series of class numbers, has fooled a lot of people over the years.

 

https://en.wikipedia.org/wiki/List_of_British_Rail_power_classifications#Type_2

I was referring to the fact that they had a derated 12SVT, putting them just below the Type 3 power band - without the derating, they'd be Type 3s.

 

14 hours ago, 25901 said:

While the 12CSVT was rated in the 37s at 1,750 hp the Australians got 2,550 hp out of the power units they put in the 2370 class loco’s 

The same basic engine block wound up – with a lot of development – rated at 3,300hp in the 58s!

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2 hours ago, Phil Bullock said:

 

Surely the 1660 hp machines were tyoe 3s and D5835 was a type 4 - the only BR type 4 with only 4 traction motors? Asking a lot of electrical systems .... and the antithesis to the explanation behind the OP's original question!

 

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

 

 

Technically yes, but there must have been some overriding issue with the electrics, if the EE engines needed to be derated to 1470bhp. So what exactly was different with the 1600 bhp & 2000 bhp versions, were the electrics beefed up too? Presumably if they were, the changes weren't deemed worthwhile, if the entire fleet got set to 1470 bhp, on receipt of EE engines.

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1 minute ago, kevinlms said:

Technically yes, but there must have been some overriding issue with the electrics, if the EE engines needed to be derated to 1470bhp. So what exactly was different with the 1600 bhp & 2000 bhp versions, were the electrics beefed up too? Presumably if they were, the changes weren't deemed worthwhile, if the entire fleet got set to 1470 bhp, on receipt of EE engines.

 

Yes I always wondered that too - not just a case of beefing up the prime mover. 

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14 minutes ago, Phil Bullock said:

 

Yes I always wondered that too - not just a case of beefing up the prime mover. 

Possibly, or was it done to exploit the short term capability of the electrical equipment, which can exceed the maximum output of the engine?

 

Jim

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It was the limit of the cooling system that determined the EE engine was set to 1470bhp. The electrics could handle the extra power. The updated class 30 had pressurised cooling systems, and had a roof access hatch booted down. BR always disliked pressurised cooling systems, instead using the much simpler non pressurised systems that were easier to top up when required. A giveaway to the problems is the more in later life of the upturned fan surrounds on the roof and the radiator intake with the missing horizontal bar to try and improve the cooling.

 

If they could have increased the HP they would have as when they were ETH fitted, the power available for traction was poor today the least. 

 

And as to the type 3 with a inferiority complex, I think people are referring to the HP to tons ratio. 

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