TRUNCH TROJAN

BEAM ENGINE

Part one by Bob Middleton


When I started the drawings for the double side beam engine I fully intended to design both the double side beam engine and the single cylinder version concurrently. As the design progressed the single cylinder version became sidelined. When I came to look at it again I did not want to just draw a ‘cut in half' version of the first engine, but draw something that was an engine in its own right and substantially original. I came up with the idea of mounting the valve chest on the end of the cylinder rather than the more usual location on the side of the cylinder.

I did some searches on the internet, but to date I have not been able to find any examples of an engine of this type. I, therefore, went ahead and to try to design an engine that would A) be different B) chunky and C) provide the builder with a few construction challenges! think I have with this design gone some way towards these objectives.

The main cylinder block (elements A to E) can be machined from slices cut out of a 3" diameter by 6" length of bar stock. I have priced this material and found that aluminium (OK for non steam running) would cost about £20. In cast iron it would cost about £30 and in brass the cost would be about £86 (guess who will not be making his from brass!).

The remaining components can be made from easily obtainable stock materials. The flywheel is 6" diameter as drawn, which is the maximum that could be fitted into the engine frame. A flywheel of 5 3/4" diameter would, I feel, be better. As this engine is a long stroke engine it should produce good power at slow revolutions, and thus require a flywheel on the heavy side.

The day that I finished the design, I caught sight of an engine on the internet that had the barrel part of the cylinder (element B in my design) clad in vertical hardwood slats bound by a couple of nice brass boiler band strips. This made me think that the Trunch Trojan would look great with this type of cladding. I would guess that slats sized at 1/4" width x 1/8" thickness would be about right.

Why have I used so many dome nuts? Because I like them!

Why have I called the engine "The Trunch Trojan" - I thought that it was about time that I gave at least one of my engines a proper name! By common consent, I live in the village of Mundesley, but due to quirk of Norfolk boundries, I am actually in the parish of Trunch (by just 30 yards) Hence the name of "Trunch Trojan" At least I thought it sounded better than the Mundesley Monster!



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Part one here  Part two  Part three

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