[calex59]

Ok, there has been a question I have wanted ask someone who knows, for years(more than I care to admit), being an electronics tech, of sorts, earned my living at it more or less for the last 15 years of my working life, I have always meant to study, but never got around to it, why diesel electric motors were used in Trains and not diesel motors. Does it take less fuel to run the generators for the electric motors than it does to run a straight diesel engine? If so, then why are not the hybrids being built today utilizing diesel engines instead of gas?

I know, it is probably simple but if anyone on here has the knowledge and feels like taking the time to answer I would appreciate it.

[bert]

The electric motors provide power to the wheel directly and don’t need lots of energy sapping transmissions and gears

The swame is true of very large earth moving machines and trucks

[nascarnation]

You need to power all the wheels to propel a locomotive because steel on steel is a very low coefficient of friction.

It’s easier to use a bunch of electric motors to do this than a complex mechanical drivetrain.

[skeptoid]

Besides the answers in 54 and 67, diesel-electrics can be operated as Multiple Units (2, 3 or 4 locomotives controlled by one engineer. Controls are standardized for simple universal synchronous coupling of units. (each unit provides the same drawbar pull)

Another advantage is dynamic braking where the motors now generate current that is wasted through a heater grid and fan in the roof of the locomotive. Have you ever noticed the diesels taking a load and the fans spinning up as a train arrives. Why are the diesels producing poweras the train slows? It's because the generators are exciting the fields of the motors causing the armatures to convert rotation to current that heats the grids and causes the fans to spin. It saves the airbrakes, and is a safety feature on long descents.

.

Hybrids aren't diesel because diesel power is heavier and more expensive - undesireble in an already heavy and expensive vehicle. There are also costs for soundproofing the noisy contraptions.

[usmcobra]

Electric motors need no clutch, where as diesel motors do.