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From: avsdT:willett@avsdS.UUCP
Newsgroups: net.railroad
Subject: Re: how do diesel engine transmissions work?
Message-ID: <637@avsdT.UUCP>
Date: Fri, 16-Dec-83 18:01:37 EST
Article-I.D.: avsdT.637
Posted: Fri Dec 16 18:01:37 1983
Date-Received: Sun, 18-Dec-83 09:06:30 EST
References: ihuxq.417
Lines: 22

* *

It is my understanding that a diesel uses electro-mechanical  means  for
transmitting  power.   The big diesel engines power a generator with the
potential being varied by the control of the engineer. The power  output
of  the  generator is then wired to the truck under the locomotive which
contains the fixed ratio gearbox and electric motor.  By changing  field
winding  potential of the generator, the generator puts out less or more
power.  The field winding can also have the polarity changed to  reverse
the  potential  to the motor to make the motor run in the reverse direc-
tion.  The large diesel engines have a very small RPM envelope and would
require  an  infinitively changing gearbox. Since that is not practical,
an electro-mechanical means of torque conversion is practical since  mo-
tors have a  much larger RPM envelope than the big diesel engines, great
torque, and can keep the diesel engine at a relatively unchanging speed.


				By no means an only answer,
	
				Michael Willett
				Ampex Corporation
				Redwood City, Ca.