In order to be able to operate the existing narrow-gauge railways more efficiently, SGP developed a diesel locomotive to replace steam locomotives. It had a box shape and two driver's cabs like standard-gauge diesel locomotives and was correspondingly smaller with a 600 hp engine. The power was transferred to the outer axles via a Voith gearbox and then passed on to the inner axles via coupling rods. Only the first three locomotives were equipped with a train heater, because ultimately all passenger cars got their own heater. To this day, about ten of the 15 locomotives are still in use on various narrow gauge railways.