Why not diesel electric trucks?
If a single diesel electric locomotive can pull 27,000,000 pounds, why has it not been scaled down to pull 20-40,000 pounds yet?
Forum Discussion
Turtle n Peeps wrote:Why has it not been scaled down to pull 20-40,000 pounds yet?
Because of this pesky problem.
Trains don't do this for fuel efficiency. They do it for reasons Ben stated. If you have 4 engines pulling a train it would be a nightmare to get all 4 to dump the clutch at the same time! :B
This is the reason.
The electric in diesel-electric locomotives is acting exclusively as a transmission.
To build a mechanical transmission capable of absorbing thousands of horsepower and then smoothly meshing it across 4-5 locomotives would be massive, complicated and expensive.
Using a generator and some electronic controls to feed electric motors in place of a transmission is dramatically simpler and allows much easier means of meshing across multiple locomotives.
It's actually slightly less efficient if you compared it to a mechanical transmission once the train is up to speed but getting the train up to speed is a huge issue.
On the other hand for trucks putting our just a few hundred horsepower with no need to mesh with other trucks, a mechanical transmission is comparatively small and simple (keep in mind, simple is a relative term).
