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From: darrelj@sdcrdcf.UUCP (Darrel VanBuer)
Newsgroups: net.railroad
Subject: Re: how do diesel engine transmissions work?
Message-ID: <740@sdcrdcf.UUCP>
Date: Thu, 15-Dec-83 11:40:37 EST
Article-I.D.: sdcrdcf.740
Posted: Thu Dec 15 11:40:37 1983
Date-Received: Sun, 18-Dec-83 02:59:16 EST
References: <417@ihuxq.UUCP>
Reply-To: darrelj@sdcrdcf.UUCP (Darrel VanBuer)
Organization: System Development Corporation, Santa Monica
Lines: 12

Diesel locomotives have no transmission as such.  Instead, the diesel drives
a DC generator which drives a series-wound electric motor which is coupled
to the wheel trucks.  A series-wound motor at very low RPM has very high
torque (and very high current consumption) so has very good starting
characteristics.  The truck motors can also run as generators for braking
and send the electricity to an extremely large "toaster".
Strings of locomotives depend on the use of accurate speed governors to run
all locomotives at close to the same speed out of a set of about 10 speeds.
Also, the electric motors are fairly good about load sharing.
(Steam locomotives were almost never ganged because there was never a way to
do good load sharing; that's why they're so big).