Bulleid Pacifics - Past or Present

Bulleid also had the cylinders re-designed, with 10" piston valves rather than 8" and improved steam passages. All but one got those.

Less obviously but still significant, this freed them up from having the same valves as the Schools. There had been a lot of tweaking of the lead and valve heads to solve starting problems with the Schools, and since the LNs had common components they got the same modifications. Unfortunately, the effect of these was to reduce port openings at short cutoffs and this was more of a problem for the way in which Nelsons were used than for Schools. The re-cylindered Nelsons could have settings to suit them.

The high sided tenders as sported by 850 were also a Bulleid-era modification, as built the tenders were mostly similar to the one behind 847.

 

Once again, a very concise reply. Thanks. Fascinating locos, the Nelsons. 'Spose we'd best let this thread get back on on topic now!

 

Regarding other modifications, one of the Nelsons was equipped with a Kylchap exhaust before the war, AIUI Bullied sold this fitment to the LNER after he fitted the Lemaitre exhaust to all of the Nelson "fleet".

Cheers,

Alan

 

Yes, I was maybe being a bit mischievous. But the point is, as often with loco design, that the real situation was far more complex than what becomes the accepted story. People often discuss the Bulleid reverser issue as a simple “they fitted the Drummond pattern instead of the Stirling pattern” (sometimes imbued with vague accusations of drawing office politics), whereas in fact there was not one “Bulleid reverser”, but two significantly different designs fitted over the years, as well as a number of incremental design changes that had the effect of enhancing the reliability - maybe not to perfection, but still an enhancement.

Tom

 

Does that apply to the big African Garratts?

 

I believe the later Garratts were fitted with the Hadfield steam reverser, patented in 1950. This had a feedback arrangement. It is a long time since I read a description of it but from memory if this type alters the feedback arrangement will drive it back to the original setting. It was similar to the ones that I had experience of on steam turbines.

 

Not exactly what you asked I realise, but may be of some relevance. The Hadfield power reverser used on postwar Garratts seems to have been one of the most reliable flavours of that component. Whatever criticisms I've seen on different Garratt loco designs from several different builders, I've never seen a single one complaining about the reverser .... with the sole exception of the electric reversers driving the Cossart valve gear (No, I don't know either!) on the short lived SNCFA (Algerian) Garrats of Class 231-132BT, one of which still holds the world record for an articulated steam loco, at 82mph, set on test in 1937 at Survilliers on the Paris (Nord) - Calais line.

The only specific special instructions I've noted for drivers are connected with drifting steam supply off, when Porta-esque front end mods are used and apply equally to non-articulated locos (NGG16A, Bure Valley No.9, L&B "Lyn" etc.).

For no other reason than to gratuitously horrify strictly UK loco design afficionados .... here, posted by 'dieselpunks', is Franco-Belge's design for North Africa. I don't know if this was taken in France or Algeria, as this loco 231-132BT11 is the record holder itself and was the very one tested in France ahead of delivery. The clothing suggests the former, but the background looks more like the backdrop to the City of Algiers than the Pas de Calais.

 

So do I .... but having just gone back to check, Hadfield's 1950 patent is described in terms of the arrangement of a locking cylinder. By itself, I can't see that being sufficient to describe an entire reverser eponymously, so my guess is the wider features you describe must be encompassed within the term "Hadfield Reverser".

Beyond a reference to valve gear layout redesign by BP quite early on, to revise the layout on one engine unit such that both sets of gear moved up or down simultaneously to control desired direction and cutoff, I've little detail on reverser arrangements. I'd be grateful if anyone could shed any more light on this.

 

10" piston valves, would that make them have the best valve to cylinder diameter ratio going? Must of been impressive machines.

 

Must HAVE indeed....

Cheers,

Alan

 

Well, with convenient thread relevance, both Bulleid Pacific classes had 11" piston valves, the MNs with 18" and the Lights with 16.375" cylinders, so no, the Nelsons didn't have the largest valve to cylinder diameter ratio going. Bulleid didn't believe in small valves, clearly.

 

As an aside, on Southern Locos FB page, 34072 in steam today

 

Brilliant news, well done to the Southern Locos team


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Good stuff, and I look forward to seeing it in person. I have a bit of an attachment to 34072 as it was my first ever flat-top, having had a ride behind it during a camping holiday with my father to Weymouth in 2001. It was a great holiday as we combined the Swanage Railway with the Tank Museum, and I seem to recall it was mostly sunny- apart from the overcast afternoon we had whilst on the railway! I also remember 80104 was the second locomotive. SLL indeed work miracles, and I'm glad what little money I've been able to contribute to the cause has been put to good use in 34010, 34053 and 34072. I'm sure a bit more of it will eventually head south, as there's still another two Bulleids to contribute to...

 

Warming fire at present, steaming soon.

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On the way home tonight back from Eastleigh I saw 34070 on the M3 between Eastleigh and Winchester. Any idea where 34070 is be moved to.


Thanks

 

On its' way to Tyseley for repairs necessary as a result of the shunt earlier this year. Then back to Herston for overhaul.

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Cheers
Lee

 

All being well, 34028's chassis will head back to Swanage as a return load.