Posts Tagged ‘#9939’

BNSF #9939 (EMD SD70MAC)

Thursday, January 31st, 2013

BNSF #9939 (EMD SD70MAC)
electric trains
Image by cliff1066™
The SD70MAC (colloquially known as a "Mac" or a "Mac 70") is very similar to the SD70M and SD70I (the SD70I’s WhisperCab feature was a build-to-order option), the main difference being that the SD70MAC uses AC traction motors. AC motors, while more simple and reliable than DC motors, require substantially more expensive inverters to generate a variable-frequency AC signal. The majority of SD70MAC models were produced with 4,000 horsepower (2,980 kW) EMD Model 710 prime movers, while later-production SD70MACs are rated at 4,300 horsepower (3,210 kW) and feature SD45-style flared radiators. They were also offered with a head-end power generation system for passenger trains. (The SD70MAC is no longer produced due to EPA regulations and has been replaced by the SD70ACe.) Over 1,500 examples of this locomotive model were produced. Purchasers include Burlington Northern (now BNSF), Conrail (engines now owned by CSX), CSX, TFM/Kansas City Southern and the Alaska Railroad. (Wikipedia)

BNSF #9939 (EMD SD70MAC)

Thursday, November 15th, 2012

BNSF #9939 (EMD SD70MAC)
electric trains
Image by cliff1066™
The EMD SD70 was a series of diesel-electric locomotives produced by the Electro-Motive Diesel beginning in 1992. Over 4,000 locomotives in this series were produced, mostly of the SD70M and SD70MAC models. All locomotives of this series are hood units with C-C trucks. All SD70 models up to the SD70ACe and SD70M-2 have the HTCR Radial truck, rather than the HT-C truck; the self-steering radial truck was designed to allow the axles to steer in curves, reducing wear on the wheels and railhead. With the introduction of the SD70ACe and SD70M-2, in an effort to reduce cost EMD introduced a new bolsterless non-radial HTSC truck as the standard truck for these models. The radial truck, now the HTCR-4, is still an option. (Wikipedia)

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