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HO - Steam Loco Kits
PRR M1 Mountain 4-8-2

The M-1
was a single prototype model 4-8-2 that was designed and produced by Juniata
in 1923. This model was locomotive 4700, shop construction No. 3819. After two
years of testing and road trials, the M-1 was approved for fleet construction.
M-1
designers, W. F. Kiesel, Jr. and J. T. Wallis transplanted features from the
I-1s decapods. They allowed for a larger combustion chamber, but left most of
the other features unchanged. Other items borrowed from the I-1s included the
following: guides, crossheads, and various machinery parts. Some special
features of the M-1's were: pilot deck-mounted air resevoir tank, 27" x
30" cylinders, 72-inch drivers, medium sized tenders, 250 pounds of
boiler pressure, KW type trailing truck, Belpaire firebox, small steel cab, a
total weight of 385,000 pounds, and could haul a load of up to 64,550 pounds.
The
original engine was built with a very small tender and no mechanical stoker.
It was hand fired, which led to great difficulties in handling this massive
machine. Stokers and larger tenders were soon implemented.
Mountains
were the first classes of superheated power to drop the "s" from
class designation. All engines were superheated by this time, so the
"s" was no longer needed.
"Mountains"
are so-named because they were considered big and powerful for such work when
first designed during World War I. These were considered to be the best steam
locomotives the railroad ever owned; they replaced the Mikados, Decapods, and
Santa Fe's. They became known as "the hallmark of Pennsy fast freight
service".
Prototype
Specifications |
Model
Specifications |
Cylinders
27" x 30"
Firebox 125-15/16" x 79-7/8"
Steam pressure 250 lbs.
Tractive force 64,550 lbs.
Engine weight-working order 382,400 lbs.
Engine weight on lead truck 59,300 lbs.
Engine weight on drivers 266,500 lbs.
Engine weight on trailing trks. 56,600 lbs.
Weight of tender, loaded 217,900 lbs. |
Length with Tender
12-3/8"
Height
Weight 2 lbs 6 oz.
Minimum radius 22"
Power Bowser DC-71
Drivers 72"
Color Brunswick Green |
Kit Photos
Assembly - Exploded View
Drawings
Photos of Superdetailed Model
Prototype Photos
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