Abstract: A regulator system for both the Diesel and the electric portions of a Diesel electric locomotive allowing more reliable operation at all locomotive speeds. Said regulator has a regulator to regulate the electric power by varying the excitation (43) of the main generator by means of orders coming from a driver control (1, 8) which set a reference current level and (17) a voltage reference level (19) for the main generator and a Diesel engine gas oil reference level (18). These levels are compared with measurements of true corresponding values (24, 30, 27) and orders (43) for increasing or decreasing excitation are delivered so that the excitation of the main generator remains inside the scope delimited by the various reference levels and a Diesel power regulator which sends out orders to increase or decrease the gas oil injection in accordance with a predetermined Diesel engine speed/injection law and in comparison with the true measurements of the injection and of the Diesel engine speed.