The locomotive had four main engines. Each engine was connected to the gearbox via a hydraulic coupling, which could be filled with oil to transmit power or drained to disconnect that engine from the transmission. One-way clutches prevented rotation of the input shafts when the couplings were drained. The engine outputs were combined in pairs by two sets of differential gearing, and the output shafts from these two gearsets were then combined by a third differential gearset to drive the main output shaft.