V4 2-6-2 No. 3403

It wasn't just company loyalties: he had a thing against the Lancashire & Yorkshire, despite having served his apprenticeship at Horwich.

 

That in itself is part of the problem, and I refer you back to the Thompson and Gresley threads where we have discussed this amongst other issues in railway history writing, at length.

 

I've read some of Cox s works and he didn't seem very keen on the LNWR either

 

Or perhaps because of having served his apprenticeship there?

 

The challenge is in distinguishing between the two motives, especially in a field where emotion is dominant. The idea of doing a low cost, high impact, thing like a smokebox is a good piece of marketing - the question I ask before parting with my hard earned is how that early PR gain is to be followed through and turned into success.

That is where some projects have done well, and others, well, less so.

 

At RA8 the Britannia had* no wider RA on Western lines than the Kings, so wasn't suitable to replace very many of the pre nationalisation express classes. They surely would have needed something with decent RA but more capable than a 5 had steam gone on long enough for post WW1 locomotives to need replacing.

(* or, it seems, arguably should have had. As discussed below it seems they were given red route availability in spite of having an appreciably greater axle load than any GWR red restricted locomotive)

 

Within this there are also different boiler designs - you can get boilers which are over/under barreled/fireboxed. Some locos have lots more boiler barrel (and thus steam space) for a given grate area than others.
If you are building a shunting loco, lots of steam reserve is good - it allows you to have a relatively smaller grate, burn less coal, then mortgage the boiler harder during bursts of activity to compensate. It does mean that you can often easily "wind" the loco if you attempt to use it hard for a sustained period. This can make some of the smaller industrials quite entertaining to fire when used for longer runs (an old boy where I'm involved will observe ruefully about some locos "she's not a line engine").

On the other hand, steam reserve is less valuable on a main line express loco, as most of the time you will be trying to work the loco in something of a "steady state", where the heat from the fire produces steam the rate at which is consumed.

This trade off is well known to boiler designers - more steam reserve is pretty much always a good thing, but available space and weight are limited, so you have to decide how much you really need!

 

Is that right, that a Class 7 Pacific, with its weight spread over one more axle than a Class 8 King's, had no wider route availability?
Even if you count the Counties as express locos, there were only three post WW1 GWR express classes, those and the Kings and Castles. Clans would hardly have been suitable to replace any of those. If you add the mixed traffic classes, Halls, Granges and Manors, the replacements would have been the Standard Class 5s and Class 4s, so again not a role for Clans.
Edit: BTW we have some serious thread drift here.

 

I don’t think it is correct, the Britannias were red route availability, the same as a Castle. They worked into Cornwall which the Kings couldn’t

 

Britannia's did, Plymouth to Penance, I've been pulled by one several times from Plymouth to Par a vv ,when holidaying at Newquay. When pulling hard the Britannia's suffered from a too and fro action,I remembered pulling away from Par with 70019 Lightning on the front, passengers heads were also too ing and froing. Please see attached 70016 Ariel waiting to take over the Cornish Rivera Express at Plymouth ,for Penzance. Summer 1953

 

Which was precisely the rationale in the boiler design of the Maunsell Z class 0-8-0 shunters. Holcroft writes (“Locomotive Adventure, vol. 1, page 150):

“It was recognised that the required conditions for the boiler were that it should have a large capacity for water and a moderate area of grate to minimise fuel losses during standing periods; the large water capacity stored the heat of the fire at the end of a movement, avoiding safety valve losses, and kept it available for starting the next movement. A standard Brighton non-superheated boiler which measured up to these requirements was adopted. Saturated steam was used because a superheater is useless and a source of waste of steam in intermittent duties of a shunter, and the engine is more responsive and controllable without it.”
​

Tom

 

Allocated red were they indeed! At 20-5 on the driving wheels according to the weight diagram I've found, and two cylinders at that, its quite a relaxation from the days when the Great Bear was heavily route restricted at 20-0 . The typical red limit was 19-10, although the Castles and Counties were 19-14. Am I right in thinking the Clan was 19-0?

 

As would mine, its almost there now, its 90% complete, possibly more and should be running sometime in 2024, the p2 will at some stage run, , as long as its trouble free for the final assembly, hopefully the issues identified with the boiler on Tornado the p2 doesn't suffer the same problems, will be learnt from, and measures taken foreward to ensure it does not effect the P2,

 

As E. S. Cox wrote of being quite chuffed that Riddles chose an L & Y chimney shape for the BR 'Standards', I don't think that statement really holds water.

 

The impression I have is that Cox wasn't very keen on anything he hadn't had a hand in designing!

 

I think it has also been noted that the fact that Cox and Eric Langridge somehow contrived to almost never mention each other in their combined works, other than an aside by Langridge that could be viewed as a dig, despite their quite obviously convergent spheres of operation, suggests that he wasn't exactly everyone's cup of tea at the time either.

Mind you, I could also imagine that being true of Langridge.

 

Specifically on the to & fro action, is that also linked to the number of cylinders - with 3 or 4 cylinder locomotives having a natural damping action?

 

In short, yes, although damping isn't really the right word.

With a two-cylinder engine and cranks at 90 degrees (which they all are) you cannot perfectly balance the reciprocating motion of the connecting rods, crossheads and pistons. You can add rotating mass to the wheels to cancel the longitudinal surging it causes, but that creates a vertical imbalance you did not previously have, creating the hammer blow to the track and underlying structures you will see referenced in various places. So most designs tried to strike some sort of compromise in their fraction of the reciprocating mass that was balanced. More balance means better running at speed (until the wheels start lifting off the rails) but worse route availability. The only mitigation really available is to make the lightest possible set of reciprocating components, relative to the mass of the locomotive.

Four-cylinder engines are easy. You have a pair of two-cylinder engines set 180 degrees apart, with immediate excellent balance because the forces cancel, unless you start using 135 degree crank angles for 8 exhaust beats per revolution. Three-cylinder engines can also be arranged to be pretty well balanced, as long as all the sets of motion are well matched in mass and near enough in the same plane. But two-cylinder engines are firmly in the realm of compromise.

 

He sounds a little envious talking about Hungarian 4-8-0 (twice I seem to remember) and impressed by the 2-6-4 from Golsdorf.

 

I think that as a designer of modern locos he just wasn't that impressed by some of the cruder efforts of his predecessors