Reader Brain Barber in Benoni, South Africa, sent us a letter asking about a monovalve, sidevalve diesel engine he remembers once being made in the U.S. He didn’t have a name, and was curious if any of these engines had survived. The engine Brian is referring to is undoubtedly the American Monovalve Diesel Engine designed by Charles A. Winslow in 1931 and manufactured for several years by the American Diesel Engine Co., Oakland, California. Warwick Bryce wrote about the engine way back in the October/November 1994 issue of GEM, and we’ve recently been in contact with California engine and tractor historian Jack Alexander who, not surprisingly, has not only researched Winslow and his monovalve design, but also has available a reprint service manual for the monovalve engine (go to lulu and enter “monovalve” in the search window). Briefly, the monovalve worked by using the flow of exhaust gas to draw in the fresh air charge. The exhaust valve remained open for both the exhaust and intake stroke, drawing in fresh air as the spent gases were expelled. At least two different engines were made, a 2-cylinder and a 4-cylinder, in versions for stationary, marine and automotive use, with a range of engines up to eight cylinders planned. Look for a further examination of this fascinating engine in the next issue of GEM.
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