(Redirected from
EMD SD70M)
Two SD70M locomotives of the Union Pacific refueling at Dunsmuir, California
The
EMD SD70 is a series of
diesel-electric locomotives produced by
General Motors Electro-Motive Division from
1992 to the present. Over 2000 locomotives in this series have been produced, mostly of the SD70M and SD70MAC models. All locomotives of this series are
hood units with
C-C trucks. Originally produced with 4000
horsepower (2,980 kW)
prime movers, later production models are rated at 4300 horsepower (3,210 kW).
Models
GM-EMD has produced several different models in the SD70 series for different customer requirements.
SD70
The SD70 is the low-nose model of the series foregoing the larger new comfort cab for the smaller standard or spartan cab common on older locomotives. This model also has DC traction motors which are more prone to failure, but simplify the electrical system by cutting out the need for inverters.
SD70M
The SD70M has a wide nose and a large comfort cab, allowing more crew members to ride comfortably inside of the locomotive than the older standard cab designs. Like the SD70, the SD70M also uses DC traction motors. The SD70M is no longer produced due to EPA regulations, and has been replaced by the SD70M-2.
SD70MAC
The SD70MAC is much like the SD70M. The main difference is that the SD70MAC uses AC traction motors. AC motors are simpler and more reliable than DC motors, but at the added cost of requiring inverters to generate a variable-frequency AC signal. The SD70MAC is no longer produced due to EPA regulations and has been replaced by the SD70ACe.
SD70I
The SD70I is a version of the SD70M which has been fitted with a cab that is isolated from the frame of the locomotive with shock absorbers. The isolation gives the crew in the cab a smoother ride. A seam is visible across the nose and on the long hood where the cab connects with the body. Due to EPA regulations, the SD70I is no longer produced.
SD70ACe
The SD70ACe is basically the SD70MAC updated to meet the latest EPA regulations for road locomotives, but several other changes were included as well. The radiator on the locomotive is nearly as wide as the cab, and looks similar to the radiator on the SD90 series of locomotives. The nose has been modified to provide more visibility to crew in the cab, producing a much more angular nose than previous models. The cables and brake lines have been routed beneath the walkways, allowing for easy access by maintenance workers.
SD70M-2
The SD70M-2 is GM-EMD's DC traction version of the SD70ACe, and the two models are nearly identical in every other respect.