Followers of these notes who own and operate 2½-in. gauge lines have called your humble servant "over the coals" for running two 3½-in. gauge "serials" consecutively ("Molly" and "Iris") and then promising yet another ("Petrolea"), and want to know what I am going to do about it. Also, other correspondents have been making enquiries about the latest type of engine oh our railways, to wit the 2-8-0 "Austerities," and suggest that a small copy of one of these would make a fairly simple and exceptionally powerful job, besides being up-to-date and possessing a certain "historical interest." Well, Curly always tries to do his best to oblige ; so with the kind approval of our good friend the Knight of the Blue Pencil, I propose to describe how to build one of the "Austerities" in 2½-in. gauge, and thus dispose of all queries and complaints at one fell swoop. Those good folk who favour the old-timers and are, waiting for the commencement of the notes and instructions for "Petrolea" won't be disappointed, for the "Austerity" notes need not interfere with that at all: On the contrary, we can "co-ordinate" (ugh !) because some of the "Petrolea" work will be detailed out in full for the benefit of novices and inexperienced workers, and the same methods can be used on the 2-8-0. Jobs like cylinder boring, wheel turning, boilersmithing, etc., are pretty much the same whatever engine one happens to be building.
British and American
The "Austerity" engines are interesting from an engineman's point of view, because we have two kinds of engines of similar size and type, but widely differing in construction, as one is built to British conventions and the other to American. The former has plate frames, a narrow firebox, and typically British details ; the latter has bar frames, a wide firebox, and transatlantic blobs and gadgets. The British engine has a greater nominal tractive effort, but the American has a much bigger grate area! I have already made a number of drawings for the American engine, and many 2½-in. gauge editions are already under construction ; so if I now proceed to describe the British version as Curly would build it, there ought to be a fine chance of comparing the working of the two varieties on sundry club tracks, or even at the next MODEL ENGINEER Exhibition.
A General Survey
In adapting the locomotive to 2½-in. gauge, I have made the usual alterations and amendments to suit the small size. The pony' truck carries the front end via a bolster below the cylinders, and has separately-sprung axleboxes. The main axleboxes have overhead spiral springs. The cylinders have slide valves instead of piston valves, as despite what I have said about them, very few followers of these notes seem to be able to turn a solid-bobbin valve and ream the liners accurately enough to obtain the proper clearance for free working without any blow. This necessitates reversing the combination lever connections and lowering the whole of the valve gear to match. The wheels are slightly smaller than "scale," in order to make use of existing castings with bosses of the size necessary for the long stroke ; this is an advantage, as it gives the engine a bigger tractive effort and renders the starting and acceleration very lively, which will be appreciated by non-continuous track owners (the "great majority !") It also allows a wider firebox than could otherwise be got in, because the foundation ring can rest on top of the frames, and the grate be made full width between them. This is not essential--far from it !--but a little extra width on a 2½-in. gauge engine is a wonderful help to an inexperienced fireman. I have added an eccentric-driven feed pump, but shall describe in full a suitable injector; you can fit both, and with the usual tender hand pump, shortage of water should be unknown.
As the boiler is big enough to supply cylinders with my "economical" valvegear and setting, there should be no shortage of steam, either. Nobody can complain about the "austerity" of the top works and trimmings.
Note : At the end of the series, LBSC went on to describe how to build the 2-10-0 version.
The Association can supply photocopies of the constructional series to members.
Drawings, castings and some materials are available from GLR Kennions.
The Association can supply the correct pattern driving and coupled wheel castings.
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This page was last changed on 06/05/2016