British Railways Power Classification

Quite so. I suspect that imperical data determined many of the BR ratings.

Regards

Reply to
Peter Abraham
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I think the problem with the Fowler 4F is that, in the interests of standardisation, Derby used axle boxes & other fittings that were designed for smaller, less powerful locos. However, what worked O.K. in a 2F or 3F was unable to cope satisfactorily with the higher power output of the 4F. The Fowler 7F 0-8-0 took this problem to even greater extremes, with essentially a LNW 0-8-0 boiler fitted on to an inadequate Derby mechanical design, leading to poor reliability / high maintenance costs, and thus their early demise, once the WD 2-8-0's became available to BR after WW2.

Bevan

Reply to
Bevan Price

Not sure it was standardisation, more conservatism - if it was good enough for Johnson then .... Have read one or two biographies where fireman hated them as they were pigs to fire. Wouldnt help with steaming.

Cheers, Simon

Reply to
simon

"Bevan Price" wrote

I think the main problem with the 4Fs was an unwillingess to steam adequately.

John.

Reply to
John Turner

In message , John Turner writes

Nothing that couldn't be solved by sending them to Swindon, then.

Reply to
Jane Sullivan

"Jane Sullivan" wrote

Gosh, for a moment I thought you'd typed 'Sweden'. Mindst you lot talk funny darn sarf. ;-)

John.

Reply to
John Turner

Did they have a lot of experience with poor steamers ?

Cheers, Simon

Reply to
simon

Didn't Bob Essery write somewhere that in his firing days he found out that the best way to work a 4F was to fill the firebox completely - literally up to the top of the firehole door - then let that burn through and the loco steamed well.

Jim.

Reply to
Jim Guthrie

OK, many thanks for all the replies. I now have the book suggested by Kevin Martin, 'The Last Steam Locomotives of British Railways', and have read up the section on power classification at the back. Presuming it is basically accurate, this is what I have gleaned:

BR did quite a re-examination of how locomotive power was calculated around

1949, and though it superficially looks like the MR/LMS systems, it is quite evolved from it.

It seems that the first value to reach was a calculation of drawbar pull, based on a series of values and a chart of Mean Effective Pressure. Boiler size, grate size, cylinder size (both diameter and stroke), coupled wheel diameter, and tube area are mentioned, as are some assumed values for firing rate, the fireman's capacity to shovel coal, and evaporation of water. Once calculated, this all comes down to a *calculated* drawbar pull figure (in imperial tons), which is then compared on a chart to where BR put the various power rating numbers (different for passenger/mixed traffic, and freight). How BR came to the comparison chart is not explained.

But, in the case of freight locomotives, the ability to brake an unfitted freight train comes into play and could change the figure for a locomotive.

And then, on top of that, real world knowledge was also often applied to adjust the figure further.

So, in no way is tractive effort alone usable to calculate the power of a locomotive. But, even here the 9 for 9F isn't listed in the straight listings of the classifications, though it is present in the comparison chart for the drawbar pull...

And what was all this in aid of? An academic exercise of me trying to understand what model locomotives I have in my collection and their suitability to haul given train types, based on theory rather than practice... :-)

Reply to
Ian J.

"simon" wrote

Only at Swindon! ;-)

John.

Reply to
John Turner

Like the Ivatt class 2, which only steamed properly when they gave it the draughting from a Dean Goods.

Reply to
Christopher A.Lee

Ivatt would have sorted it out but he was too busy. Anyway Stanier had taught him to delegate so it was given to one of the new LMS regional centres.

cheers, Simon

Reply to
simon

Actually, no. It was sent to S.O.Ell at Swindon, who was _the_ draughting guru.

Reply to
Christopher A.Lee

Sorry, meant one of the new BR regional centres :-)

CHeers, Simon

Reply to
simon

Whoosh

;-)

Kevin Martin

Reply to
Kevin Martin

The message from Christopher A.Lee contains these words:

Isn't that what Simon wrote: Swindon = new LMS regional centres...

Reply to
David Jackson

From what I've heard it is, especially when it comes down to interpretation and opinion - then everyone can be right.

Cheers, Simon

Reply to
simon

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