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Posting-Version: version B 2.10.1 6/24/83; site rabbit.UUCP
Path: utzoo!linus!philabs!seismo!harpo!eagle!allegra!alice!rabbit!jj
From: jj@rabbit.UUCP
Newsgroups: net.railroad
Subject: Re: how do diesel engine transmissions work?
Message-ID: <2295@rabbit.UUCP>
Date: Fri, 16-Dec-83 15:06:27 EST
Article-I.D.: rabbit.2295
Posted: Fri Dec 16 15:06:27 1983
Date-Received: Sat, 17-Dec-83 08:16:05 EST
References: <417@ihuxq.UUCP>, <740@sdcrdcf.UUCP>
Organization: AT&T Bell Laboratories, Murray Hill
Lines: 40


Hmmmm.  The little baby GE yard engine we used in a coal
yard went like this.

1)  Two deisel engines, on governors, running at constant
speed, throttle varied by governor automatically.

2)  big control in cab varied the PRIMARY current in generators
connected to each engine.  This varied the amount of voltage/
current that was generated by each generator. 

3)  Generators were connected directly to traction motors,
with a HUGE contactor to reverse things or stop things.

The control was, I thought, done most reasonably in the
lowest power part of the machine. <i.e. using a generator
as a gain device with a mechanical power input.>

Braking in the yard engine was strictly by shoes on wheels,
and by car brakes (cursed baby compressor!  Took DAYS to get 50 cars
pumped up!))

I don't have any experience with bigger engines, but
the system seems really nicely adaptable.  The addition of
a big "toaster" for braking seems reasonable enough.  

Comments?   How do road engines work?

(It seems to me that, since current in a motor and torque
<at any given speed> are a more or less monotonic and linear
function, controll of multiple engines in the D.E. style
is trivial, you just set each for equal traction motor
current, this just about guarantees equal loading and tractive
torque.)


-- 
-Diogenes stopped here-

(allegra,harpo,ulysses)!rabbit!jj