Prototype History
The EMD GP40 began as a four-axle diesel locomotive originally intended for freight service, and was one of a series of models introduced in 1966 with the introduction of the EMD 645-series engine. It used a turbocharged 16-cylinder version of the engine and was built alongside the GP38 (with a Roots-blown 16-cylinder engine) and the GP39 (with a turbocharged 12-cylinder engine). All three which were built to GP35 expectations; aside from serving as an initial replacement. The SD38, SD39, SD40 and SD45 were contemporary six-axle models of the series.
The high-horsepower GP40 often struggled while hauling long and heavy freight trains because of its adhesion problems. This was mostly solved by the GP40-2.
While the GP40 shared many components with the GP35 (as well as the GP38 and GP38-2), a simplified electrical system and the introduction of an alternator-rectifier system (replacing the DC generator) improved reliability. The 16-cylinder 645 engine subsequently gained a reputation for reliability and solid performance. The GP40 was a sales success, selling over 1,200 units over its production run. It was discontinued and replaced by the GP40-2 (its "Dash 2" series upgrade) in 1972.
In early 2014 one UP GP40 was rebuilt by EMD into a GP59ECO mated to a slug.
Source: Fandom.com
