 A metadyne unit consists of a rotating machine, which converts the constant voltage supplied by the battery to a constant current, which feeds the motor.The metadyne system is more efficient than conventional starting resistances, particularly when the locomotive starts and stops frequently, or when it needs to run for long periods at slow speeds.For cable laying work, the metadyne-equipped locomotives could pull trains of 100 tons at for considerable distances, without any sign of overheating.