In July 1938 the SNCF put into service a 225 ton twin unit diesel locomotive powered by a pair of Sulzer 12 cylinder twin bank engines.
At the time of construction they were the most powerful engines ever installed in railway traction. The 12 cylinder twin bank engines were each rated at 2,200hp at 700 rpm on the one hour rating. Cylinder size was 310mm by 390mm (12.2in by 15.4in).
Electrical equipment was supplied by les Forges et Ateliers de Constructions electriques de Jeumont, each half unit having a main generator, three traction motors, an axle driven exciter, an auxiliary generator and other subsidiary equipment. The total of six tractions motors are of the four pole series, with forced ventilation, permanently coupled in parallel.
The Sulzer powered 262BD1 was one of a pair of twin units ordered by the PLM, the second twin unit, 262AD1 is shown below, this machine was powered by four MAN 1,050hp engines.
Fittings on the locomotives were standardised where possible to keep spares to a minimum, likewise the bodyshells reveal much similarity.
Both twin units were retired from service during 1955.