EMD E-unit - Engines

Engines

While there were some cosmetic differences between E-unit models, the major line of development was technological, and largely that of increasing power. For example, the first model in the series, the EA/EB, was rated at 1800 hp (1300 kW). An intermediate unit, the E3, was rated at 2,000 hp. The last unit in the series, the E9, was rated at 2,400 hp (1800 kW). This enabled heavier trains to be pulled by the same number of locomotives, or the same weight of train could be pulled faster.

Early models (EA/EB through E2) used the Winton 201-A engine that had been purchased by Electro-Motive Corporation, the immediate ancestor of the Electro-Motive Division of General Motors. This engine was originally designed for submarine use, and wasn't well suited to the sustained full throttle operation often demanded in railroad service (especially in mountain operation). It was not unusual for heavy repairs to be done en route on one non-functioning engine while the other engine propelled the train at reduced speed. The 201-A engines used in E-units were 900 hp (700 kW) V12 units.

Models E3 through E9 used the EMD model 567 engine, named after its engine displacement in cubic inches per cylinder. Although similar in some ways to the earlier Winton design, the 567 model had been developed by EMD specifically for locomotive use, and exhibited excellent performance and reliability in high speed passenger train service. The 567 had a greater displacement per cylinder than the 201-A and ran at a higher maximum rpm, elements which when combined gave greater engine output. The 12V-567 V12 model used in the E3 through E6 developed 1000 hp (750 kW). The E7 model used the 12V-567A rated at 1000 hp (750 kW). The E8 used the more advanced 567B unit, with improved exhaust manifolds and other enhancements to give 1,125 hp each. More development resulted in the 1200 hp (900 kW) 567C engine used in the E9.