Locomotive Tonnage/long trains

nw-mailing-list at nwhs.org nw-mailing-list at nwhs.org
Mon Aug 7 23:09:39 EDT 2006

In response to Chuck's question about tonnage ratings, this might be
a partial answer.

C. E. Pond outlined the steps for design of new steam locomotives in
a speech to the Delta Nu Alpha Transportation Fraternity on December 19, 1952:
''The General Superintendent of Transportation furnishes a list of
such items as:
Train Tonnage
Speed Desired - Maximum and Average
District or Districts over which the locomotive will operate.
From the Chief Engineer we obtain information on the grades,
curvatures, clearances and track structure limits. With this
information we are then in position to calculate the tractive effort
required, locomotive wheel arrangement and wheel size and approximate
weight of the engine. The boiler pressure and cylinder size are then
established as the tractive formula depend upon the boiler pressure,
diameter of the cylinders, length of stroke and diameter of driving
wheels. Having this basic information, we then calculate the steam
requirements, boiler heating surface, boiler diameter and length. We
also calculate the fuel requirments, grate area and firebox dimensions.''

Since this applies to new construction, it does not really answer the
question of existing power.

For those who are really math inclined, and interested "The Steam
Locomotive Its Theory, Operation and Economics" by Ralph P. Johnson,
Chief Engineer of Baldwin, published in various editions by
Simmons-Boardman beginning in 1942. There is an entire chapter
(Chapter XII) beginning on page 199 of the first edition entitled
"Tonnage Ratings" If you are an engineer type (mechanical not
locomotive) it is worth seeking out, and I think there is a new
reprint of it out in recent months. But be warned, if you are not
into formulas and calculations, this in not in your league.

Long Trains
As the esteemed Mr. Bundy reported
"On Oct. 25, 1967, N&W operated a 450-car coal train. According to
my source, it had three engines on the head end and five units pushing.
Thought I'd heard that they had a pusher in the middle also. "

This was an era of attempts at record setting, there were reports of
a Russian record train, so N&W set out to better the record. It was
also the time to try and run longer and longer trains. The N&W
Magazine of November 20, 1967 had a report of the 450 car train,
which was powered by 3 SD45s at the head end and five more remote
controlled SD45s near the middle of the train. It was nearly 3.5
miles long running from Iaeger to Williamson. In the same magazine,
on the facing page is a story about running remote controlled long
heavy coal trains of up to 189 car, 189,000 ton train on the
Shenandoah Division.

On November 15, 1967 the railroad ran a 500 car, 48,170 ton train
between Iaeger and Portsmouth, Ohio. It was powered by 3 SD45s on the
head end, and three more SD45s as remote control units about 300 cars
back. I seems that there was an extensive discussion on this list
about a year or so ago about these big trains.

Ken Miller

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