The Sarawak Trophy Engine

by LBSC

Meet "Dyak"

The type of engine illustrated is one which was asked for in my little "locomotive election," and I finally decided upon it after sounding the wishes of the "rank and file," as you might say, of brother loco. men who follow these notes. It can be built by even a tyro brother quite easily within the year. The few castings necessary are on: sale by our advertisers, and the cost is low. All the rod and sheet materials needed are to the usual commercial sizes. The average small lathe will tackle all the turning; one reason why I avoided large driving wheels was to make easy work for tyro brothers whose lathes are not "up to scratch." The boiler, too, whilst being a free steamer, capable of supplying the cylinders with all the steam they are ever likely to need, is of quite moderate dimensions, and the average amateur's brazing outfit will do the needful. All details are as simple as possible, consistent with efficiency. One point I want to impress on all "Dyak" builders is this˜that I have started to build the engine myself (not for competition !) and unless something unexpected happens, I shall keep the job in advance of the notes, so that if any snag should turn up, it will be found and corrected instead of getting into print. First we'd better survey the job. To make the work as easy as possible, the main frames are practically cut in straight lines, the only curves being the clearance for pony wheel, and the radius at back of trailing wheel. Buffer beams are made of angle; and with 3/32 in. frames, the only stiffeners needed will be the pump stay and pony bracket. The pony truck can be knocked up out of a bit of frame steel, or a casting can be used, as desired. Cast horns are fitted, with single-flanged axleboxes like "Fayette," two springs being used to each axlebox. The driving wheels are the same as "Mary Ann's," and in full size would work out at 5 ft. 2 in. diameter.

The cylinders of a big engine of this type would be about 19 in. by 26 in., so we can make the small ones somewhere about the "scale" equivalent, say 13/16 in. by 1½ in., the castings supplied for "Helen Long" and similar engines working in quite nicely. The valves are fiat slide, in an ordinary steam chest with removable top, and big gland and tail-rod bosses. Steam and exhaust pipe connections are inside the frames. Oil is supplied by a mechanical lubricator between the frames at the leading end, driven from an eccentric on the front coupled axle.

The valves are actuated by Walschaerts gear. I personally prefer Baker gear, and would unhesitatingly fit it to an engine of this type built for my own use; but as you know, it is always my policy to face facts. Everybody is entitled to their own opinion, and I respect the opinions of others; therefore, as I happen to know that some of the prospective builders of this little locomotive are red-hot "Buy Britishers" and wouldn't tolerate an American valve gear. on their job at any price, and as Walschaerts gear (a Belgian invention˜forgive my smiles) is fitted to both Southern and L.M.S. 2-6-0's, Walschaerts gear is specified for the little "Dyak." It is arranged in simple and sturdy fashion, the link swinging in brackets bolted to the overhung guide bar yoke, and the radius rod going right past the link, the rod being lifted and lowered by the simple slot-and-pin arrangement used on both L.M.S. and L.N.E. locomotives. The engine is arranged for left-hand drive, which is the handiest for getting at the cab lever in an engine of this size, without burning your fingers.

To get back on the main line again; the little "Dyak's" boiler is a straight-barrelled gadget with a big Belpaire firebox. I thought at first of specifying a taper barrel, as on both L.M.S. and Southern engines; but remembered that the parallel barrel would save bur friends the tyres one brazing job. The Belpaire wrapper is easiest for staying, using my pet crown girders which are easily riveted to the flat top. The same former does for both back-head and throatplate, so really there is no extra work, because if the boiler were round-topped, you'd still have to rivet on a separate wrapper to go between the frames. The firebox is of ample capacity without being a "barn," and there is plenty of steam space in the wrapper. The backhead of a Belpaire boiler also gives more space for fittings, which will be of my usual pattern, all made up from rod material.

Regarding top works, straight-topped running boards. with no splashers will call forth sighs of relief from the tyro brigade! The cab is the same as "Fayette's," and the whole lot can be made from 20-gauge hard-rolled brass sheet, with the minimum bf trouble. The tender will be a six-wheeler, almost exactly similar to "Annie Boddie's."

Now trot along to the Exhibition and take a large-sized eyeful of the silver casket; then, if you covet same, make a main-line dash to any of our advertisers' stands there castings and parts are on sale! The instructions for building the little "Dyak" will, all being well, run on non-stop week by week until completed, and sketches will be supplemented, where possible, by pictures of my own engine 'under construction. I leave the rest to your good selves!

The constructional series appeared in The Model Engineer between 6th September 1934 and 21st March, 1935.
The Association can supply photocopies of the constructional series to members.

Drawings, castings and some materials are available from GLR Distributors.

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