BR's unrated locos

No, not the beginnings of something naughty [oh, matronnn .... ]

I was recently reading about the LMS' Big Bertha and the LNER's Garratt and noticed that neither loco seemed to be given a power classification by BR. I know these were two fairly unique engines unsuited to normal train workings, so there might not have been much point classing them, but it got me thinking,

a) How many engines/classes went unrated by BR

b) Just going off their tractive efforts, if these two had been classed, what would they likely have been? Well into double figures I imagine, though presumably tractive effort wasn't the only consideration and I reckon my quick calculations are a bit off. I get ~20F for Big Bertha and ~30F (!) for the Garratt
(I couldn't find a proper guide to working out BR's power class, so extrapolated from an MR scheme I did find which went up roughly in increments of 2000lbf)

 

I'd suggest that they were unclassified for a reason. The Classification was an indication of a loco's ability to work a train over a distance. I believe that both of these locos were tried on traffic duties - and both failed miserably. As you say, there was more to it than Nominal Tractive Effort, a pretty useless figure in its own right.

 

Little bit harsh. The LMS garratts were unclassed too, according to my Observers book, and, if something less than a triumph of engineering, they did work trains for many years.
Might it be simply the case that if the object of the exercise was to provide equivalence points between different types, there was little point where there were no equivalents?

 

Bertha was only ever a banker and never intended to work a train, I understand, so I can see why it was never classed.

I forgot about the LMS Garratts, though I was surprised to read t that they escaped classification too, given how many were built

 

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