Electro-Motive Division SD70ACe

When the new EPA Tier 2 emissions standard came into force in 2004, the SD70MAC was replaced by the SD70ACe. The core was a new variant of the 710 series prime mover, which worked with a lower internal pressure and therefore emitted fewer exhaust gases and particles. As already the last SD70MAC, they again made 4,300 hp. Due to more modern traction electronics, the starting tractive force could be increased to 191,000 pounds. 

With the Tier 3 emission standard from 2011, the locomotives were sold unchanged as SD70ACe, but these in turn had a revised engine with now 4,500 hp. In the meantime, the cab has also been revised because many crews had previously complained about excessive volume and rattling noises.

In addition to the standard variant, modified variants were also built for individual customers. The Canadian National received four SD70ACe-P6, which have a traction converter on each axle and not just one on each bogie. The BNSF ordered 20 SD70ACe-P4, which have only four traction motors. In contrast to the GE AC44C4, however, the inner axle of both bogies is not powered.

The largest customer was Union Pacific, which received a total of 799 units. Of these, 281 are designated SD70AH, weighing 8,000 pounds more. In second place was the BNSF with 660 units. Other railroads that each ordered more than 100 units were the Kansas City Southern, Norfolk Southern and Ferromex.

The SD70ACe/LCi was developed for export to mining companies. The LCi stands for “Low Clearance international”, as these have a smaller loading gauge for the special area of application. 184 of the 205 LCi are being used by BHP Billinton in iron ore mining in the Pilbara region of Western Australia. Another variant is the SD70ACe/45, which is being manufactured in Brazil.

Before the introduction of the new Tier 4 emissions standard from 2015, attempts were made to adapt the engine accordingly. However, since this did not succeed, no new SD70ACe could be registered in the contiguous USA. It was succeeded by the SD70ACe-T4, which used the four-stroke engine from the 1990s that now had been upgraded. The cheaper locomotives with two-stroke engines were still built for export and some could still be sold in the USA due to the emissions credits that were still available.