. . . "A U engine is a piston engine made up of two separate straight engines (complete with separate crankshafts) joined by gears or chains. It is similar to the H engine which couples two flat engines. The design is also sometimes described as a \"twin bank\" or \"double bank\" engine, although these terms are sometimes used also to describe V engines.This configuration is uncommon, as it is heavier than a V design."@en .