Superheaters and Throttle Linkage

NW Mailing List nw-mailing-list at
Mon Sep 1 11:43:28 EDT 2008

This has been a great discussion for somebody who is trying to learn the
details of steam locomotive operations. I hope to hear more along this topic.

Many thanks to Jimmy Lisle for sharing the diagram. Some of us engineer
types can't talk without drawing or looking at pictures.
Keep it up!

Rick Huddle

----- Original Message -----
From: NW Mailing List
To: nw-mailing-list at
Sent: Wednesday, August 27, 2008 10:10 AM
Subject: Re: Superheaters and Throttle Linkage

I've always marveled at the 'American' brand front end throttle. It is
a beautiful complicated casting that uses an array of small valves similar
to an automobile engine valve that open progressively. The casting also
includes the superheater connections with what I call their A and B
chambers for saturated and superheated steam respectively. The whole thing
rested comfortably and readily accessible beneath the removable panel
behind the stack. The exterior operating rod and bell crank that Gordon has
referred to are a clue to where the throttle is.

It is one of the most modern and sophisticated components of the late
steam era. It would look good in my living room as a (large) coffee table.

Ted Goodman (Columbus)

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