Abstract: A split-torque transmission in which a high-speed engine drives a substantially lower speed drive shaft, such as a helicopter rotor drive shaft, comprises a pair of selectively laterally inclined cross shafts for drivingly connecting a corresponding pair of helicopter engines with the helicopter rotor drive shaft. The transmission arrangement achieves a relatively high overall speed reduction, such as required in the transmission of power to the main rotor of a helicopter, with a minimum number of reduction stages, gears, and bearings. The lateral inclination of the cross shafts and the adjustable positioning of the associated gears to vary that inclination permits the engines of a two or more engined helicopter to be relatively widely separated and at the same time compact the drive arrangement in the longitudinal direction.