The 9F 2-10-0

Should it have been a 2-8-2 instead?

Discuss.

 

No, as built and in traffic it worked just fine, often exceeding expectations, I doubt usefulness and changes in check rail height decades later were a design consideration.

 

Agreed, a splendid locomotive which did exactly what it was designed to do plus more!
Andy

 

Big, plenty of power and a rather handsome beastie too, what's wrong with that?

 

I read some years ago that Riddles did consider a 2-8-2, but decided a 2-10-0 would be a better proposition.

 

Pity it came too late. It would have been most useful during the war, as the Austerities were.

 

Is there anything to discuss? There was nothing wrong with the 2-10-0 that turning it out as a 2-8-2 would have improved and an eight coupled has got to be a weaker loco than a ten coupled if the axle loads are the same.

 

Depends on how partisan you are. Initially the 9F was proposed as a 2-8-2 BUT Riddles had appreciated the quality of the German 2-10-0s during his time in Germany and thought that a redesign to create the 2-10-0 would provide a better locomotive. Although not of engineering bent I presume that the major point of difference between the 2 options would have been the driving wheel diameter hence the only interest I can now see is the discussion of which would have been the better design to adopt.

 

Actually I believe the major consideration was that BR would be stuck with loose coupled box-on-wheels freight wagons for most of the life of the locos, therefore the better ashpan design and higher speeds permitted by a 2-8-2 weren't relevant and the better adhesion of a 2-10-0 was. Even so there was concern over the restricted ashpan and redesigned boiler that were found to be necessary for the 2-10-0 and it nearly caused a reversion to the 2-8-2 which had been intended to be the same as a Britannia except for the wheel arrangement. Neither the boiler nor the ashpan turned out to be a problem in service, at least I've never seen any reports of poor steaming that were blamed on the design.

No-one on the design team expected that the 9F's would haul passenger trains at 80plus as they did on occasion!

If you were doing a new build now for modern conditions I think one would pick the 2-8-2.

 

Bit of a leading question and my answer is no ( surprisingly) - The clues in the name '9F'. Perhaps there might have been fewer 9f's and they could have been built as a more task specific loco with smaller drivers - would have allowed smaller cylinders or even more grunt, more ashpan space and a shorter coupled wheelbase - the speeding up of freight services and block freights didn't happen soon enough for them
Yes there should have been a 2-8-2 but instead of the Clan - intended as a 6 / 7mt in the same mould as the V2.but with better route availability.
Able to do the jobs too fast for an 8 or 9f, too heavy for any of the '5's'and able to operate on routes that 7 and 8 P's were too heavy for. Building 100 of these instead of Clans, 5mt's and 9fs would have worked out fine...

 

" A booster fitted 2-8-4 with a wide firebox... on the other hand..." would have been a treat as a new Lickey banker, but it would have been a struggle to try and find anything else useful for it to do...

 

But weren't 9Fs timed at up to 90mph on passenger duties on occasion? So it is hard to imagine just what jobs there were available that were too fast, save absolute top-link expresses.

There's always an interesting debate to be had about exactly which (if any) BR standards were or weren't justified, but it is hard to see what a 2-8-2 with presumably the same or similar boiler to a Britannia could do that couldn't be met by either a Britannia, or a 9F. So why do you need yet another class?

The 9F's combination of high adhesion, high tractive effort, but surprising speed where permitted, proved very effective on the S&D when they were allowed to operate passenger trains. Presumably that is the sort of duty that you would have in mind for a 2-8-2, but actually the 9Fs performed just fine.

Tom

 

A big fan of Berkleys are you?

 

Yes Tom, You could also argue that a 9F Can do anything that a 5MT can do
In my scenario the 9F is a smaller wheeled version ( so only good for about 70 then). The 9F is an amazingly versatile machine, probably more versatile than its designers envisaged, and its only limitations would seem to be its ashpan capacity and flangeless driver neither of which is a major concern - but both would be improved as a 2-8-2 as would route availability

But on your second point since we are in effect playing Fantasy standards MPD then there would be:
7+XP 4-6-2 (3 cylinders /42sqft/6ft 2's) a Slight step up from a Britt. More like a WC/BofB
6MT 2-8 -2 (2 cylinders /36sq ft/ 5ft 8's 250psi) - Produced instead of the Clan and 5MT
4+MT + 4-6-0/ 2 -6-4 tank - As produced
2+MT 2-6-0/ 2- 6-2 Tank - as produced
9f 2-10-0 (4ft 8's otherwise as produced)

 

I'd say driving wheel diameter is rather irrelevent considering the speed 9F's got up to, clearly no handicap to staggering performances by freight loco's.

 

I do wonder what they did in wear to their connecting rod bearings while they were doing it though. My guess is that was why TPTB had kittens when they found out.

 

Doh! That's what I meant.

 

All that reciprocating motion thrashing around at 90mph must have given the maintenance people something to do. I believe it was after one of the exploits on the GCR got into print in C J Allen's column in Trains Illustrated that a speed limit was put on the class, I may be wrong but, if true, it was very rare to apply speed limits to particular loco classes in this country