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Re: Someone please explain shifting gears in a diesel
Author: PNWRailfan
Date: 12-16-2010 - 05:31
Nope, they are diesel electric, so there is no mechanical transmission. But even being electric, they have to transistion which is much like shifting gears. More info;
"Transition
Transition is the process by which the transmission of a diesel-electric locomoitve is brought from series wiring to parallel wiring. When in series, all current in the locomotive pass through all motors: this produces maximum low-speed force in the motors, i.e., maximum starting torque. When in parallel, current is divided among the motors: this produces maximum high-end efficency, i.e., highest motor speed. This is just as with the wiring internal to DC motors, where having the motor wound in series develops high starting torque, while placing the motor in parallel will develop high speed. Electrically, as current increases through the motors in a circuit with a given total current and voltage, the voltage drop across each motor will decrease: parallel circuits apply the total voltage to each load (i.e., in this case, motor), while series circuits apply the total current to each load.
Not all locomotives can make transition -- yard locomotives are often wired only for series. The motors on a diesel-electric road locomotives are often capable of making multiple transitions, with both trucks and motors on a truck capable of being switched into series or parallel wiring. "
From;
[members.localnet.com]
"Transition
Transition is the process by which the transmission of a diesel-electric locomoitve is brought from series wiring to parallel wiring. When in series, all current in the locomotive pass through all motors: this produces maximum low-speed force in the motors, i.e., maximum starting torque. When in parallel, current is divided among the motors: this produces maximum high-end efficency, i.e., highest motor speed. This is just as with the wiring internal to DC motors, where having the motor wound in series develops high starting torque, while placing the motor in parallel will develop high speed. Electrically, as current increases through the motors in a circuit with a given total current and voltage, the voltage drop across each motor will decrease: parallel circuits apply the total voltage to each load (i.e., in this case, motor), while series circuits apply the total current to each load.
Not all locomotives can make transition -- yard locomotives are often wired only for series. The motors on a diesel-electric road locomotives are often capable of making multiple transitions, with both trucks and motors on a truck capable of being switched into series or parallel wiring. "
From;
[members.localnet.com]
