In 1966 EMD introduced a new line of locomotives
based on the 16-cylinder 645-series prime mover. The ?40-series?
included a six-axle and four-axle model, the latter being the GP40.
A total of 1,145 units were produced between 1966 and 1972. These
turbocharged 3,000hp locomotives were used primarily in road
freight service. The GP40 was a versatile locomotive that could be
found across the US hauling drag freights over mountain passes and
leading high-speed intermodal trains across flat terrain. Three
rooftop radiator fans at the rear of the long hood differentiate a
GP40 from its lower horsepower counterpart, the GP38, which has two
fans at this location.
Concurrent with GP40 production, EMD offered a lower horsepower,
non-turbocharged locomotive based on the same 645-series prime
mover. The four-axle GP38 was rated at 2,000 hp and had the
advantage of costing less than the GP40. A total of 727 units were
produced between 1966 and 1971 when the model was superseded. The
wheelbase of the GP38 was identical to that of the GP40. Both units
shared the same EMD road-switcher style body that was introduced
with the GP35 in 1963. A desire for standardization caused the GP38
to share the same wheelbase, frame and many external components as
the GP40. The GP38 was purchased by large and small roads alike. It
was routinely found in local and road freight service throughout
the US. Many GP38s and 40s are still in service today.
Options on the Atlas GP38 and GP40 models include a long hood
with or without dynamic brakes and an underframe with 2,600 or
3,600 gallon fuel tanks.