History:  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".

Complete Kit and Accessories:  The locomotive and tender complete kit has all of the parts to build a working model. You may wish to add your own details or purchase our "Super Detail Kit" if available. Some models have an optional painted engineer and fireman, smoke unit kit and other assemblies available as optional equipment to compliment your kit-building needs.