In 1929, H.J. Coventry designed (and made castings available for) a vertical, stationary marine engine, 1/3rd HP, 2-cylinder, compound style. Its construction was described in The Modelmaker magazine at that time, and castings advertised in same. It was described again to a new audience in the 1950s in The Miniature Locomotive magazine, and again to yet another audience in the 1970s in a series of articles that ran for a time inLive Steam Magazine.
Castings have been unavailable since the 1970s.
The complete set of castings for the "1/3 HP Compound Engine" will be ready in 2022. A preview of the castings can be seen below. The complete set of drawings, as well as Mr. Coventry's construction articles, are available at this time (please see below).
These are the initial castings produced by FRIENDS MODELS in 2022. You'll see the low-pressure and the high-pressure cylinders, the columns, the flywheel, the bedplate, the bearings, the eccentric rods, and the eccentric straps.
1-1/4" and 2-1/4" bores, x 1-1/2" stroke
Compound....exhaust steam from the high pressure cylinder, powers the low-pressure cylinder
Stephenson valve gear, reversed via hand wheel with worm gear
Develops 1/3 HP at about 600 RPM
All parts can be handled on a 9" lathe, and a small bench-top mill or mill/drill
Click the button at right, to purchase the complete set of drawings, and the construction articles, for the H.J. Coventry "Marine Compound" engine. $140.00, plus $35.00 shipping.
(For shipping to countries other than the USA, please inquire).
Mr. Coventry's ORIGINAL marine engine (built 1929), "live and in color".
A 1970s-era advertisement for the H.J. Coventry 1/3HP Marine Compound engine. This engine was designed in 1929 and has not been produced, or available, since the 1970s.
Another example of the 1/3 Horsepower Compound Marine engine by H.J. Coventry; this one by a different builder and featured in Modeltec Magazine some years ago.