Diesel locomotive engines work using a combination of diesel fuel and electricity; these engines rely on an internal combustion system to provide some power, which is used to turn a large shaft. This shaft then signals a generator to produce electricity; this electricity is distributed to power motors in the wheels, called traction motors, which then help the train move.
Diesel engines, like other internal combustion engines, are larger and heavier than electric and gasoline engines. For locomotives, this means diesel engines must work in conjunction with another power source, as they generate limited amounts of power.
Diesel engines come in two main forms: diesel-mechanical and diesel-electric. Diesel-electric engines are most common. They contain several key components: a main generator, traction motors, and a large control system that contains an engine governor, gearbox, electrical components and rectifiers.
When diesel trains turn on, power is first generated in the prime mover, or the body of the diesel engine. It is then converted into electricity, which moves to the gearbox in either AC or DC currents. The gearbox then accepts, processes, and distributes electricity to the wheels. It uses a complex system to convert power and supply the right amount of power to the wheels. Meanwhile, the engine governor regulates RPMs and fuel consumption. It is connected to the throttle that conductors use to drive trains. As conductors change throttle settings, engine governors respond accordingly to match engine power with the appropriate gear.