35011 General Steam Navigation

As we showed in the podcast, there was weight on the inner face of the centre wheel sets (381lbs on the rhs, 305lb on the lhs), but there was also additional weight inside the other four wheels, about 161 lbs in each of the leading drivers, and 163lbs in each of the trailing drivers. The inner motion was balanced by the centre driving wheels, the outer motions was balanced by all six wheels (if I'm understanding the text in the drawings)

 

So Bulleid encountered similar problems and rather failed with steam reversesr as the GWR had done about 40 odd years previously.

 

The big problem seems to be about placement. Stirling steam reversers had a good reputation, but were always mounted on the running plate where access for maintenance is very easy. The harder you make access, the more likely you will have reliability problems, IMHO.

Tom

 

I seem to remember something about a crank axle breaking on an unrebuilt, can't remember any details, but I think that the unrebuilt axle webs were unbalanced, the rebuilts were balanced, was there some experimenting going on inbetween?

 

There was an accident at Crewkerne in April 1953 in which the crank axle broke on 'Bibby Line'. The whole class was withdrawn for inspection, and some other cracked axles were found (some were fine); the class returned to service starting in May 1953, i.e. after about a month.

Subsequently (i,e. more than a year later, long after the class had returned to service with their original pattern crank axles) some, but not all of the class had a new design of balanced crank axle; and subsequent to that (another year or more later) rebuilds started. I am not fully clear on how the chronology of those events stack up; for example, was the revised pattern crank axle a consequence of redesign from Crewkerne, or independent; and if so, why did only some of the class receive it - was it because rebuilding was on the horizon?

Tom

 

The revised design was a consequence of Crewkerne; if I recall correctly some, if not all, the Merchant Navies had a temporary fix applied to relive the stress in the axle, all of them received greater and more frequent inspection until they received the revised, balanced, design. From the research I've done at least one MN (35019 French Line CGT) received the replacement design before rebuilding, and all Bulleid pacifics received the replacement design upon rebuilding, if they didn't already have it, hence my comment on the podcast that if we could get a crank axle from a rebuilt locomtoive we'd be happy. The replacement design was such that it could be used in any Bulleid pacific, all that had to be swapped was the chain driver sprocket for the eccentric for the new middle set of valve gear.

 

There were three Arrangement of Driving Wheels drawings done, dated 1940, 1953 and 1957.

 

DL Bradley (RCTS Locomotives of teh Southern Railway, Part 2) gives the following data:

Found faulty on inspection after Crewkerne:
35001
35012
35023
35024

Not found faulty after Crewkerne, but replaced anyway:
35025
35026

From the above, I assume that the remaining locos continued in service with the original axles - possibly with the minor modification you mention, but not having a replacement.

Subsequently replaced with a balanced crank axle:
35023 (October 1954)
35027 (November 1954)
35026 (January 1955)
35011 (February 1955)
35019 (April 1955)
35010 (June 1955)

Rebuilds commenced from mid 1956.

From the above list, 35023 and 35026 had new crank axles after Crewkerne, and then again with the new pattern but before rebuilding. 35011 was one of six to receive a new crank axle before rebuilding.

Tom

 

Useful information, I don't have that book. If it's correct, that furthers our case for using the balanced design with an unrebuilt machine. Any possibilty you could take a picture of the info and send it to me via email ro direct messenger or something?

 

PM sent.

Tom

 

Like I regularly tell my esteemed colleague,
"Old loco drawings are for the guidance of wise men and the obedience of fools."
As locos were to some extant hand-built by the fitters on the shop floor and don't always conform to the existing drawings.
As other groups have found to their cost.

(also quoted as "...for the obedience of fools and the guidance of wise men.") In Douglas Bader's Reach for the Sky, this quote is attributed to Harry Day, the Royal Flying Corps First World War fighter ace.)

 

And Harry Day was channelling Solon from well back in the BC era, whose quote was "Laws are for the guidance of wise men and the blind obedience of fools", which is the version I prefer - blind obedience is more the sin than obedience per se.

 

Not watched yet all of the podcast, and lots of discussion about the wheel balancing. The A1 trust practically checked their driving wheels. You can read about how it was done here.
https://www.p2steam.com/2016/10/31/getting-balance-right/

The biggest priority I would have though it getting the loco undercover as it is still sat basically outside, What is happening with that ? The barn which partly covers it only seems half built. There was a photo in the SCR magazine showing the barn at its previous location when the farmer donated it and it seemed longer, so is some of it still lying around somewhere waiting to be put up ? Will the sides get sheeted in etc. It would seem sensible to me to concentrate on that first so you have somewhere inside to work.

 

Alwayss

Always struck me as ironic that Bader would quote that, since he lost his legs due to dangerous low flying in blatant breach of the rules... The challenge being that you only find out that you were in fact the fool rather than the wise man after the event, which may be too late.

 

The barn is being worked on, the SCR are making good progress with it, and we're supporting them for the reasons you've laid out, having a building to work in makes the work more pleasant and helps protect the locomotive.

 

We all start as fools but some gain wisdom as the years pass.

 

Presumably there are two components which need to be balanced - the mass of the coupling rods, which will be approximately the same for all 6 wheels, plus the proportion of the rotating mass of connecting rods - which affects the centre two wheels. The horizontal reciprocating forces of the pistons and rods will be largely cancelled by the three cylinders although there will be a slight "Wiggle" due to off-centre effects.

 

Broadly speaking, that is what the original design calculation drawing shows

 

Thanks srapley
- just a thought, but didn't they change to a stronger coupling rod design with a higher strength steel and non fluted design and heavier? Might this be why they increased the balance weights?

 

Finally had a listen to this today whilst doing some housework, very impressive as is usual regarding @Corbs work, I’ll try and throw some cash in 35011’s direction after a few bills are paid off, it came across as a very interesting piece (certainly to this Midland man out in the Eastern )