The Midland Railway experimented with "compound" steam locomotives, a system (and I may well get this wrong) where, instead of just exhausting steam after it's moved the cylinder once, the steam is put to further work in a secondary set of cylinders.
It was immensely complicated to pull off (something about balancing the steam pressures), and this engine, no.1000, was something of a noble failure. Compounding never became popular in Britain.
But this model... ah, there's something rather lovely about it.
Not just the Midland Railway's lush livery -- a shade of red known as Crimson Lake -- but the amazingly fine detail. The crest on the side of the cab is just 4mm across, yet the level of detail is quite extraordinary.
None of the three models the NRM has so far produced have been of prototypes in which I have a particular interest (I was hoping for a Class 76 electric, or better yet a delicious North Eastern Railway no.1 electric shunter), but I hugely admire what they've done and I hope it continues to be a big success for them.
2 comments:
This is indeed a superb model.
I think your description of the compound steam mechanism is essentially correct. It was devised for stationary engines, and is more suited to such, and to marine engines, where the rotational speeds are slower, and space is not so much at a premium. The complication of multiple pistons, and the space they occupy, makes them less practicable for locomotives, and the high speeds involved means that lubrication could be a major difficulty (especially before synthetic oil was invented, with its higher resistance to problems of contamination [ie in steam engines, water!]).
The greater efficiency in terms of fuel use was probably more significant in pumping or marine engines running for days or weeks non-stop, than with the (relatively) few hours' running of a typical steam loco.
(Turbo-charging of IC engines is of course an attempt to improve efficiency similarly by utilising heat that would otherwise be wasted, though by a radically different mechanical method. It's tempting to speculate on how that approach might have been worked out for use in steam engines.)
Noble failure is too harsh from my point of view. 45 MR 4P Deeley compounds were build (including no. 1000) and in the 20s those 4P compounds were more or less copied as LMS 4P Fowler compounds (190 locomotives).
And compounding became at least popular with Webb and the LNWR ;-)
Teutonics, Dreadnoughts, Greater Britains and 3 cyl. and 4 cyl 0-8-0 compounds.
Regarding the utilization of the heat otherwise being wasted (in steam engines):
1) feed water heaters used the steam exhaust by the cylinders to preheat the feedwater for the boiler (of type Knorr in Germany, ACFI in France, Elesco and Worthington in the US)
2) preheat (?) boilers used the heat from the smoke to preheat the water in the boiler; most prmominent example is the Franco-Crosti boiler chiefly used in Italy, but also in small numbers in Germany and Great Britain (an alteration of the class 9F)
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