Vernon Davy has written:

'Diesel and diesel electric locomotives' -- subject(s): Diesel locomotives

Diesel electric is used on locomotives because the diesel electric system is much cleaner and quieter and more efficient than the old steam locomotives. The diesel

fuel is used to run a generator which produces electric power which is used to power

the electromagnetic drive motors mounted on the locomotives axles!

locomotives are used to propell railcars. They can be in a push or pull mode. Locomotives are generlly diesel or diesel electric. If a locomotive starts to lose its propullsion power it will require maintenance.

John Draney has written:

'Diesel locomotives, electrical equipment' -- subject(s): Diesel locomotives, Electric apparatus and appliances, Electric machinery

I am not an expert but my understanding is the electromotive configuration is better suited to locomotives. An internal combustion engine is used to run a generator or alternator and the electricity then runs the electric motors that drive the wheels.

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The diesel engine IS used in small locomotives, usually with a hydraulic transmission. Larger locomotives use either electric or hydraulic drives but the prime mover is still a diesel engine.