EMD SD60 - History and Development

History and Development

The development of the SD50 and SD60 series locomotives in the late 1970s and early 1980s was spurred by the introduction of 3,600 horsepower (2,700 kW) GE B36-7 and GE C36-7 locomotives by EMD's main competitor General Electric. In 1980, the SD50 model was added to the EMD Catalog. However, the SD50 quickly became a 'dud' in terms of sales due to poor mechanical reliability and an overly complex electrical distribution and control system that was unique to the EMD 50-Series Locomotives. EMD therefore quickly commenced development of the SD60 series, which would eliminate the weaknesses of the SD50. Although the carbody and frame are nearly indistinguishable from the earlier SD50, the SD60 featured the new 16-cylinder EMD 710-G3A prime mover, AR-11 main alternator, D-87 traction motors and a microprocessor-based control system that governed various systems within the locomotive (e.g. wheelslip & transition). Mechanically, the SD60 proved to be more reliable and fuel-efficient than the SD50, but it was not a resounding success in terms of regaining the market share that was lost due to the electrical & mechanical issues that plagued the earlier SD50 model. EMD claimed that three SD60 units could replace four SD40-2s.