Quote:
Originally posted by beavis
they use the same method for the commuter train that i used to take.
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All modern diesel locomotives work this way. The diesel generates electricity and the wheels are actually turned by electric motors. (Which is one of the reasons why Westinghouse is a major manufacturer)
According to howstuffworks.com:
"The five- or six-speed transmission on most cars allows them to go 110 mph (177 kph) or faster with an engine-speed range of 500 to 6,000 rpm. The engine on our diesel locomotive has a much smaller speed range. Its idle speed is around 269 rpm, and its maximum speed is only 904 rpm. With a speed range like this, a locomotive would need 20 or 30 gears to make it up to 110 mph (177 kph).
A gearbox like this would be huge (it would have to handle 3,200 horsepower), complicated and inefficient. It would also have to provide power to four sets of wheels, which would add to the complexity.
By going with a hybrid setup, the main diesel engine can run at a constant speed, turning an electrical generator. The generator sends electrical power to a traction motor at each axle, which powers the wheels. The traction motors can produce adequate torque at any speed, from a full stop to 110 mph (177 kph), without needing to change gears."