In 1925, Baldwin turned out boxcab No. 58501 that can be considered the USA's first diesel locomotive. Its official designation 12-OE-1000/1 CC can be understood as “12 cylinders, oil engine, single 1000 hp engine, wheel arrangement CC”. In fact the middle axle of each bogie was not powered, leading to the A1A-A1A wheel arrangement. Power came from an inverted Knudsen V12 two-stroke diesel that sat between the two cabs. After trials, the locomotive was deemed unsuccessful and scrapped after a short time.

Baldwin's first attempt at a diesel road locomotive was the DR-12-8-1500/2, which was also called the “Centipede” because of its many axles. Each locomotive had one cab and two bogies, which in turn were divided into four powered axles and a two-axle leading bogie. Power was provided by two eight-cylinder engines with 1,500 hp each.

The type designation was formed from this data, as well as the total number of twelve axles with eight powered ones. Usually two locomotives with a total output of 6,000 hp were coupled together. The UP initially ordered two Centipedes, which were not accepted and were then used together by Baldwin as demonstrator.

The series variant was ordered by only three railroads. The largest customer was the Pennsylvania Railroad with 24 Centipedes, which were later provided with a shorter gear ratio for freight traffic and were derated to 2,500 hp. Seaboard Air Line and Nacionales de Mexico each ordered 14. The NdeM locomotives were later equipped with multiple controls and used as helper locomotives. Ultimately, all Centipedes were scrapped because they could not assert themselves against their competitors.

The DRS-6-4 series included road switchers that had a total of six axles, four of which were powered. The three less powerful variants each had a six-cylinder with 660, 750 or 1,000 hp, with only the most powerful variant having a turbocharger. 

SNCF A1AA1A 62030 in September 1983 at Bobigny depot

Didier Duforest

The first variant with 660 hp was manufactured from 1946 and 100 of the 106 locomotives went to the SNCF. They were derived from the four-axle VO-1000 and had a carrying axle in each bogie to reduce the axle load. They were given the designation A1AA1A 62000 and remained in service until 1994. The remaining six went to Morocco.

Sectional drawing of the DRS-6-4-660NA

Didier Duforest

The DRS-6-4-1000 received the same six-cylinder engine as the 660 hp variant, but here it delivered 1,000 hp thanks to a turbocharger. From 1948, 20 of this variant were delivered to Algeria on behalf of France. In 1949 a single naturally aspirated 750 hp locomotive was delivered to Morocco and used to transport phosphate.

The variant with 1,500 hp was powered by an eight-cylinder with turbocharger and was also available from 1946. In the USA it was replaced by the AS-416 in 1950. The DRS-6-4-1500E was manufactured for export until 1952. Ultimately, more than half of a total of 91 DRS-6-4-1500 were sold to Algeria, Morocco and Tunisia.

The prototype of the DT-6-6-2000 was commissioned by the Elgin, Joliet and Eastern Railway, which ultimately used 27 of the 45 locomotives of this type. These were transfer switchers for handing over freight trains between marshalling yards. A central cab lay between two engines. Two naturally aspirated eight-cylinders were used in the prototype, which were replaced in series production by six-cylinders with turbochargers. Many locomotives were later modernized with new engines from Baldwin or EMD, each with 1,200 hp.