You can never be sure what will initiate a train of thought. Lets face it, a vague relative of Ann’s once got hit on the head by an apple and look what happened to him.
I was quietly reading the latest copy of my magazine when I came upon a large picture of Gresley’s “Cock of the North”. I always thought that this was a magnificent engine, almost good enough to have come out of Swindon (I can pay it no higher compliment). By the time Gresley and his team built this they had studied a Castle and absorbed some of Mr. Churchward’s ideas’ so it should have at least steamed well and pulled a bit better than his early efforts.
It had a number of its problems (according to the magazine) which came about by the fitting of a water preheater, a ghastly looking thing strapped to the side of the boiler. Many of the Companies tried this system in various forms only to find that they created more problems than they solved and despite the savings seen, the cost of maintaining them, adding them in the first place and repairing the damage they initiated far outweighed any benefit. On the GWR, Mr.Curchward took his usual phlegmatic approach to railway engine construction, he fitted top-feed and ignored the problem. However, some “herberts” don’t learn and continued to struggle with the problem, how many of us remember the Crosti boilered 9Fs with that weird arrangement stuffed in and under the left or should that be right side of the loco, anyway the side with all the extra gubbins, it had exhaust leaking from everywhere other than the chimney? They didn’t last long!
The next to try this wheel arrangement was Mr.Bullied, who built his Merchant Navy class during WW2 and followed them with the West Country and Battle-of-Brittan classes. These were all lighter than the LNER and LMS versions and had even worse problems moving trains from a stand-still or hill climbing. Due to a number of other problems most of the three classes were rebuilt, A shame really because and I loved the “spam cans”.
Finally, we move on to Mr.Riddles, who by this time should really a known better. His Britannia class locos were either loved or loathed depending on the sort of classes they replaced, the GWR men disliked them because they were intended to replace the Kings and Castles which were efficient, had good riding qualities and were very sure-footed. Something for which the new introductions were not known and from memory seemed to preclude them from being used on the Devon Banks.
By now you must have grasped my thinking 4-6-0s are very sure-footed,
4-6-2s slip and slide and are poor at starting or climbing with heavy trains.
Mr.Gresley must have found this to be more and more of a problem when his trains became longer and heavier and he looked for new answer rather than building more and heavier 4-6-2s.
The logical answer was either 2-8-0 or a Mikado wheel arrangement 2-8-2, which gave the best pulling power and spread engine weight where it could do the most good. His thinking eventually gave us the P2 class (“Cock of The North”), which, logically, should have solved his haulage problems and consigned the 4-6-2 to history. So what happened? Personally I haven’t a clue so I had to find a man who does and I wish to thank those at www.p2steam.com . I quote:-
No. 2001 was put to work in Scotland, followed shortly by the other members of the class. The ACFI feed water heater fitted to No. 2001 proved troublesome, requiring, as it did, exhaust steam to pre-heat the injector supply which required the locomotive to run with the regulator constantly open, something that was not possible on the Aberdeen route.
The locos did prodigious work hauling 550 ton trains on the Aberdeen route but No. 2001 had an appetite for coal. As their careers progressed other faults became apparent, they showed a tendency to run hot axle bearings and develop excessive wear in the motion.
As noted before, Cock o’ the North and Earl Marischal were both equipped with the A4 front end and when No. 2001 was at Doncaster in 1937 for this work the opportunity was taken to fit the loco with Walschaerts valve gear as well as removing the feed water heater. If the class had a common Achilles heel it was the leading pony truck which proved poor at “steering” the leading driving wheels and set up frame stresses which led to big-ends running hot and crank axle trouble. Gresley had given the locos a leading truck similar to type fitted to his K3 moguls, a design which was perpetuated in the V2 class (although these were successfully modified to resolve the issue).
As a small class which required higher than average attention it inevitably came under close scrutiny from Edward Thompson, the L.N.E.R.’s new C.M.E. following Sir Nigel Gresley’s premature death. The issues with the leading truck may well have contributed to his decision to rebuild all six P2s as A2/2 Pacifics during 1944. Thus the magnificent Mikados effectively became extinct, the final blow falling when the rebuilt engines were scrapped in 1961.
So why did the LNER give up? Again, I don’t know, but Mr Thompson did make some controversial decisions, which are still debated today. Myself,
I think Gresley’s decision was a good one, a 2-8-2 was the answer and that with experimentation and experience any of the problems could have been solved. After all, around the world the 2-8-2 seemed to be the answer to many a maidens prayer. MPT
The side without the offending clutter, it has much cleaner lines.
Having got the above off my chest, it does have some relevance to the story, I shall begin to unravel my contorted thinking……...WHY?
Why did the 4-6-2 Pacific become so popular in the UK? Mr.Churchward was the first to try the arrangement and he found it big, heavy and very slippery to manage, both in starting and hill climbing, something which was very important given the GWRs mainline into the West Country. The sure-footedness which the Castles showed in the early interchanges between the GWR and the LNER, when the 4-6-0 moved the long and heavy trains cleanly out of Kings Cross and up the Gasworks Tunnel incline without faltering. Mr Gresley modified his creations so that they steamed better, but still retained their slippery characteristics.
The next advocate of the 4-6-2 was Mr.Stanier, who built a variety of fine engines for the LMS, but despite his GWR training and friendship with Churchward decided to adopt the 4-6-2 for his top link locos, and these like those before them were slippery when starting or when called upon to climb, their saving grace as with most 4-6-2 was probably their sheer weight on the tracks, something which is of doubtful benefit.