The Michel engine was an unusual form of opposed-piston engine. It was unique in that its cylinders, instead of being open-ended cylinders containing two pistons, were instead joined in a Y-shape and had three pistons working within them. These engines were produced by Hermann Michel of the Michel Engine Company of Kiel, Germany, in the 1920s and 1930s. A US patent application was filed in 1921 and granted in 1926. This Michel engine should not be confused with the contemporary Michell engine, which was a swashplate engine.