Prototype for everything corner.

[SHMD]

6 hours ago, Steven B said:

How about a Webb 0-6-2 in LNWR colours, out on the mainline in 1986 with a blue/grey Mk1 BSK

Isn't it cute? by Arnie Furniss, on Flickr

 

Steven B

 

That's Stalybridge for anyone who was wondering. The then platform 2.

 

Lovely.

 

 

Kev.

[Mol_PMB]

59 minutes ago, montyburns56 said:

This one definitely wasn't supplying enough ETH....

 

Chester 1985

 

 

The lights are on though (but nobody’s home).  I wonder whether an eth loco was on the other end. Did the AC 

Mk2s still have dynamos? 

[ianmacc]

2 hours ago, melmerby said:

Which shows up the limits of the TOPS system.

 

There are of course the "new" Class 21s used around Eurotunnel and based on HP (1500 or 2100) are type 3s or type 4s.

I didn’t realise they were that high powered. There are even gaps in the 3x class range (32, 34 and 36) they could have occupied! Or 49… 

[45125]

2 hours ago, russ p said:

 

Seemed to give more power

It will have done. Having seen the effect of the ETH been turned on whilst on a load bank it certainly saps the traction power, turn it off again the traction power recovers.

[keefer]

From discussion on previous threads, it was estimated that ETH took about 350-400hp from the engine's output.

[DY444]

16 hours ago, ianmacc said:

I always thought that you couldn’t recover the ETH as engine horsepower on the 31s hence they were underpowered?

 

When the eth is switched on it imposes a load on the engine which thus has less power available for traction.  When the eth is switched off its load is absent and thus more of the engine power is available for traction.  So you can "recover" it for traction use by having the eth switched off.

[LMS2968]

I think it was Eric Langridge who commented that, until they began tests of ETH from diesel locomotives, it hadn't been realised how much work the old steam engine boiler had been doing!

[russ p]

16 minutes ago, LMS2968 said:

I think it was Eric Langridge who commented that, until they began tests of ETH from diesel locomotives, it hadn't been realised how much work the old steam engine boiler had been doing!

 

Never thought of that before,  but the amount of heat supplied to a train as steam must translate into to the amount of heat supplied to a train as electricity 

In theory the most efficient must be a oil fired train heat boiler from a diesel

And just to burst everyone's brain quite early in the day how would this formula apply to an electric boiler in EM1s and 2s ?

[Titan]

6 hours ago, keefer said:

From discussion on previous threads, it was estimated that ETH took about 350-400hp from the engine's output.

 

You have to remember that heating load was dependent on the length of train and the weather conditions.  A six coach train in cool, but not cold conditions would quite likely only need double digit horsepower to heat it.  The Class 31's had a high ETH index - much higher than required for any service train that they might operate, because the intended use was for pre heating/cooling of rakes of air conditioned empty coaching stock en-route to Kings Cross, where they could be heating 13 vehicles from cold in sub zero temperatures, which would require in excess of 300bhp. Just as well it was mostly downhill! Whenever a 31 would be hauling a sensible sized train for a type 2, the ETH requirement would probably be about half of that, even in frosty weather.

Edited September 22, 2021 by Titan

[melmerby]

57 minutes ago, Titan said:

 

You have to remember that heating load was dependent on the length of train and the weather conditions.  A six coach train in cool, but not cold conditions would quite likely only need double digit horsepower to heat it.  The Class 31's had a high ETH index - much higher than required for any service train that they might operate, because the intended use was for pre heating/cooling of rakes of air conditioned empty coaching stock en-route to Kings Cross, where they could be heating 13 vehicles from cold in sub zero temperatures, which would require in excess of 300bhp. Just as well it was mostly downhill! Whenever a 31 would be hauling a sensible sized train for a type 2, the ETH requirement would probably be about half of that, even in frosty weather.

When they were new the class 31 had a steam heat generator, powered by the diesel fuel.

 

To give you a general idea of what it's about, Convert to kW (746W = 1hp).

Therefore 300hp would be about 225kW of heat available from the locomotive.

 

The 31/4 had an ETH of 66 = 330kW

(according to wiki https://en.wikipedia.org/wiki/British_Rail_Class_31)

[St. Simon]

14 hours ago, ianmacc said:

There are even gaps in the 3x class range (32, 34 and 36) they could have occupied! Or 49… 

 

Not necessarily, TOPS numbers apply to coaches and wagons, so they may be (or were) coaches / wagons allocated numbers in the 32xxx, 34xxx, 36xxx or 49xxx ranges.

 

Simon

[SamThomas]

3 hours ago, DY444 said:

 

When the eth is switched on it imposes a load on the engine which thus has less power available for traction.  When the eth is switched off its load is absent and thus more of the engine power is available for traction.  So you can "recover" it for traction use by having the eth switched off.

I used to work for a well know supermarket driving HGV's - the fridge was driven by a generator deriving it's power from the road engine.

By terpory switching off the fridge the trucks would go up long drags in a higher gear so certainly auxilery power taken from any traction engine will mean less power at the wheels.

[melmerby]

7 minutes ago, SamThomas said:

I used to work for a well know supermarket driving HGV's - the fridge was driven by a generator deriving it's power from the road engine.

By terpory switching off the fridge the trucks would go up long drags in a higher gear so certainly auxilery power taken from any traction engine will mean less power at the wheels.

The wikipedia article I linked to said that on certain subclasses of 31 the power for ETH was taken off a seperate winding and couldn't be recovered for traction power.

 

As regards the fridge, on a car the aircon uses engine power that will result in a worse fuel consumption.

 

In India on holiday we heard from our tour guide that the cost of hiring a TATA coach depends on whether the aircon is on or off due to the change in fuel consumption.

 

[montyburns56]

21 hours ago, Mol_PMB said:

The lights are on though (but nobody’s home).  I wonder whether an eth loco was on the other end. Did the AC 

Mk2s still have dynamos? 

 

I was wondering that myself.

[Silly Moo]

When your loco is too long for your Ratio engine shed. Seen at the Swanage Railway. 

Edited September 22, 2021 by Silly Moo
Adding photo

[Jeremy Cumberland]

5 hours ago, melmerby said:

The wikipedia article I linked to said that on certain subclasses of 31 the power for ETH was taken off a seperate winding and couldn't be recovered for traction power.

That's just on the electrical side though; you cannot use the ETH windings to drive the traction motors. However, the ETH still requires engine power, and if you turn off the ETH, you will have more engine power available for the main generator. It is only when you have an entirely separate engine for the ETH generator that ETH is decoupled from traction power (until you run out of fuel, when you find the ETH generator engine has been using it all ).

[melmerby]

3 minutes ago, Jeremy C said:

That's just on the electrical side though; you cannot use the ETH windings to drive the traction motors. However, the ETH still requires engine power, and if you turn off the ETH, you will have more engine power available for the main generator. It is only when you have an entirely separate engine for the ETH generator that ETH is decoupled from traction power (until you run out of fuel, when you find the ETH generator engine has been using it all ).

Quote from Wiki:

"The early conversions tapped off the main generator such that none of the ETH power was available for traction even if the ETH was not being used. The traction power output of some of the 31/4 subclass was therefore limited to a maximum of two-thirds of that of the non-ETH variants, this did not help the performance of an already somewhat underpowered locomotive"

[montyburns56]

Yeovil Town 1964 by KDH Archive

 

 

[Jeremy Cumberland]

1 minute ago, melmerby said:

Quote from Wiki:

"The early conversions tapped off the main generator such that none of the ETH power was available for traction even if the ETH was not being used. The traction power output of some of the 31/4 subclass was therefore limited to a maximum of two-thirds of that of the non-ETH variants, this did not help the performance of an already somewhat underpowered locomotive"

Ah, I see. They didn't get a separate ETH generator. Instead, main generator windings were used for ETH, on a separate circuit from the traction motors.

 

I suppose that if the locos were intended for pre-heating and ECS then this would have made sense. It would have made them pretty useless for hauling trains, though (as the article says).

[rab]

Taking us almost back to where this thread started, how about this for a 

Definitely Mixed Up formation

(Posted by Johnathan Coop on the

Saltash Community Club Facebook page):

 

[irishmail]

On 21/09/2021 at 15:03, ianmacc said:

I always thought that you couldn’t recover the ETH as engine horsepower on the 31s hence they were underpowered?

Back in the day as a Second Man we had a turn working the 02:04 newspaper train to Nottingham, usual power was a class 45/1, but one day we had a 31/4,  We tuned the ETH off until we got up speed so yes it does give more power. 

[russ p]

1 hour ago, melmerby said:

Quote from Wiki:

"The early conversions tapped off the main generator such that none of the ETH power was available for traction even if the ETH was not being used. The traction power output of some of the 31/4 subclass was therefore limited to a maximum of two-thirds of that of the non-ETH variants, this did not help the performance of an already somewhat underpowered locomotive"

 

It's not actually electrical the engine is turning both generators and obviously with a load on both it takes more horsepower to turn both but if only one is loading its easier to turn the other 

Think of riding an old bike with a dynamo on the wheel if they were set too tight you used more energy to turn the pedals 

[45125]

1 hour ago, melmerby said:

Quote from Wiki:

"The early conversions tapped off the main generator such that none of the ETH power was available for traction even if the ETH was not being used. The traction power output of some of the 31/4 subclass was therefore limited to a maximum of two-thirds of that of the non-ETH variants, this did not help the performance of an already somewhat underpowered locomotive"

All class 31/4s have a Brush dual wound alternator (BL100-30) fitted, one set of windings is for the auxiliary supply and the other one is for the ETH supply. The engine governor on a 31/4 has the idling speed raised so as not to flog the engine to death when suppling ETH and give the right voltage range .The 31/0 that were converted for static ETH duties used the main generator but could supply traction power. The only locos that tapped the main generator for ETH are the Deltics.

 

Don't believe everything on Wiki.

 

 

Al Taylor

[DY444]

2 hours ago, melmerby said:

Quote from Wiki:

"The early conversions tapped off the main generator such that none of the ETH power was available for traction even if the ETH was not being used. The traction power output of some of the 31/4 subclass was therefore limited to a maximum of two-thirds of that of the non-ETH variants, this did not help the performance of an already somewhat underpowered locomotive"

 

Ah the joys of Wikipedia.  I'm afraid that is a complete load of nonsense. 

 

The eth was not taken from the main generator on any of the 31/4s; all of them had Brush dual wound alternators to supply the eth and auxiliaries as indeed did most BR diesel classes not built with eth and subsequently converted. 

 

That renders the rest of it irrelevant but in any event it is total drivel as the reduction in traction power in such a scenario would not be fixed and permanent; it would depend entirely on the heating load.

Edited September 22, 2021 by DY444

[ianmacc]

That Wikipedia entry is the basis of my thinking so yes that does suggest that Wikipedia is inaccurate. Having tried previously though I wouldn’t waste valuable time attempting to correct it as there is a hardcore of reactionaries on there who’ll constantly change it back again!