Smith steam engines were designed and built by E.W. Smith & Sons Pty Ltd. of Coffs' Harbour, NSW, Australia. They were built from 1921 to early 1950, when the firm closed its doors.
This engine was designed specifically to drive the bench rollers on the main bench of the steam-powered sawmills through sprockets and chains. The requirements of the design were: It must not stick on center when required to start or reverse; it must be reversible at any steam pressure up to maximum; and all steam control and reversing must be from a single lever control.
The cylinder bore is 3-3/4 inches and the stroke is 4 inches. The three cylinders are single-acting with early manufacturing fitting cast iron pistons from a Ford Model T. Reversal is by a plate valve actuating through 45 degrees. The main valve is rotary, held against the face by spring loading, shimmed up to only a few ounces of pressure on the face. Thus, cylinder drain cocks have never been fitted and are not necessary to release condensate.
Lubrication to the cylinder bores and valves is done by an elementary design of lubricator, using steam cylinder oil. The crankshaft, big-end bearings and lower ends of the pistons are lubricated by oil filled in the crankcase to the crankshaft level floating on the water. Any condensate that passes the piston rings in operation is expelled through the gooseneck pipe, which rises from the bottom of the crankcase, thus leaving the oil floating inside. No drains, stopcocks or plugs should be fitted to the gooseneck. Improper use of such could easily cause water build-up, or by accident could drain the water and oil, damaging the engine.
As an apprentice steam and sawmill maintenance engineer at Lowanna Easter Dorrigo (25 miles from Coffs' Harbour), I worked on repairs and installation of Smith engines - both used and new units - from 1934 to 1939. The sawmilling company had 14 steam powered mills. The Smith engines were used extensively in all eastern states, I believe, in New Guinea and perhaps New Caledonia and Fiji, but never in Western Australia.
The builders never painted the engines and so it is now left to the restorer to treat the engine with the color desired. The disposition of the steam valves, pipes, rods and single-lever control has required condensing in size to fit onto a 3-by-2-foot cart, as opposed to installation on a mill bench of approximately 8-by-5-foot. Where steam is not available at exhibition, the engine can be operated on compressed air. Lubrication may be done by using a heavy grade of mineral oil.
The flywheel throws the balance off some in the absence of being connected to bench rollers by sprockets and chains.