In the twenties, ALCO offered a range of diesel-electric, or oil-electric locomotives under the name “AGEIR”. This name stood for ALCO as the manufacturer of the main mechanical construction, General Electric as the supplier of all electric traction equipment and Ingersoll Rand as the supplier of the diesel engine. The New York Central ordered a 150-ton variant for experimental freight service on its Putnam Division. It was numbered 1550 and designated class DEf.

It had the wheel arrangement 2-D-2 and the same traction motors as the Q-motor switcher. Multiple controls were installed in case more of this type were built. The 750 hp engine and four traction motors were enough for service with freight trains of 500 to 550 tons. Although no more were built, this locomotive is being considered the first successful diesel-electric locomotive in the USA for road service. In 1946 it was rebuilt into a slug for switching service. The class DEp No. 1500 that was built by ALCO for passenger service at the same time was no success.