9F why does not having a flange on the centre wheels stop it being mainlined

Check rails are only fitted on the inside of curves, so the problem doesn't arise on plain curves per se. It's the wing rails on point vees which are effectively on the outside of the curve of the turnout and thus more likely to be struck by the flangless wheel.

 

Exactly, hence my enquiring how much offset there might be at those places between the wheel and the running rail.

 

This from above might help

I think it wouild be more complicated than that - there's side play in the wheelsets and the frames actually bend slightly too. The flangless wheels are also wider than standard, though how much and whether the widening is evenly spaced between front and back of the wheel, I'm not sure.

 

Further to this, Ian Mellor (Redgate Models) did another take on the mikado and also a 'BR Standard 8F'

 

Whatever else this thread has done, it has shown that this subject is very complex and that the consequences of getting it wrong could be very serious. Small wonder, then, that NR go for the cautious option; ban 9Fs outright. It only involves (less than) a handful of locos of one class and I doubt if the total number of people who are seriously interested would fill one train. I'm sure NR have bigger fish to fry, at least they should have!

 

Please don't blame Network Rail, this restriction goes back to early 1980s.
David Shepherd discusses the 9F flangeless driving wheel ban in "A Brush with Steam" published in 1983.

Has anybody actually applied the RSSB T&RS subject committee in the past 20 years to take a 9F on the mainline? I undsterstand it is this committee (with representatives across the industry) who would assess such a proposal rather than NR directly.

 

Seemed a certainty at one point with a lot of work done to get the loco to required standard but as you say it never went further. Think the ownership changed to JH mid repairs too.

 

I was on that tour and it doesn't tell the whole story!

RAB3L

 

What would the turning circle of a 9f be if its wheel was flanged ?, would it still be practical ?

 

Depends on the diameter of the turntable

 

Or its radius. ;-)

 

Do tell...? 34 years is long enough for the bodies to be decomposed by now!

 

You're right, most of the railwaymen at Didcot seemed to die very soon after retirement! It was timed at 90mph down Hatton by more than one person.

 

Not bad for a 'freight' engine... ;-) Wouldn't have fancied hitting any check rails at 90 though...

 

And black 5's are restricted to 60mph! 5000 when on the SVR went over 80mph and was a bit of a rough runner by all accounts.

Cheers Dave

 

in those days its widely accepted that control would have a flexible approach to steam loco maximum speeds, for instance ,i can remember the first after dark run with 34027 on electrified southern metals and she was going really fast though hook on the fast, i would say nearer the old speed limit for steam, than the 75 mph she was ment to be timed at.

 

And wouldn't it increase flexibility if they did so now.

Cheers Dave

 

I hope you're refering to its mainline stint while at the SVR.

9fs were regularly timed in the 60s. Wouldnt like to watch the motion at that speed.

 

All interesting stuff.
If there is a risk of the wheel hitting a check rail, is there also a risk of it running off the side of the main rail ? and if it did would it de-rail the rest or would it be forced back on.
Just wondering.