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Bowser - HO - Steam Loco Kits
PRR M1a Mountain 4-8-2

History:  In 1930, 100 engines of class M-1a were developed. They were built by Juniata, Baldwin, and Lima. They were slightly heavier than the M-1's, and had Worthington feedwater heaters with the mixing chamber back of the stack. Two compressors were mounted on the left side. Ten M-1a's, along with twenty M-1's were used for passenger service.

In 1946, several M-1a locomotives were upgraded and re-classified M-1b. Some important changes made to the locomotive included a twenty pound increase in steam pressure to 270 pounds and installation of circulators in fireboxes, which increased heating surface by thirty-five square feet. These changes occurred after the locomotives were sixteen or more years old; consequently, their final years were spent hauling the heaviest loads of their lifetimes.

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.

Part #DescriptionPrice
1-100435  Assembled Valve Gear Kit, PRR M-1 & M-1a * n.a.
1-100442  Engineer & Fire-Man PRR M-1, M-1a * n.a.
1-100443   Assembled Piping, PRR M-1, M-1a * n.a.
1-100450  Pennsylvania M-1a Mountain Kit * n.a.
1-100460  PRR M-1a Super Detail Kit * n.a.
1-100416  Smoke Unit, M-1, M-1a, N2, Northern, USRA Mountain * n.a.

Kit Components and Replacement Parts:  The following parts are listed in order to identify parts in your kit or to replace parts that have been lost, damaged or simply worn out.  This is not a complete list of all of the individual parts available for this model - please call Bowser with your specific requirements if you cannot find the parts you need.  You may also use our on-line catalog to find parts by description.  Please note that part numbers with a price of "Call Us" may be part of an assembly and may not be available as a separate purchase item.

Part #DescriptionPrice
1-100431  Side Rod Kit (included in M-1 & M-1a Kit) * n.a.
1-100434  Lead Truck Kit (included in M-1 & M-1a Kit) * n.a.
1-100437  Trailing Truck Kit (included in M-1 & M-1a Kit) * n.a.
1-100444   Instructions (included in M-1 Kit) * n.a.
1-100451  Boiler, Frame, Drivers, Tender, Trucks (included in M-1a Kit) * n.a.
1-100452   Instructions (included in M-1a Kit) * n.a.
1-100453  Miscellaneous Kit (included in M-1a Kit) * n.a.
1-100456  Casting Kit (included in M-1a Kit) * n.a.
1-100458  Frame, Drivers, Cylinders (included in M-1a Kit) * n.a.
1-100459  Casting & Walk Kit (included in M-1a Kit) * n.a.
1-100461  Long Haul Tender Parts Kit (included in M-1a Kit) * n.a.
1-100469   Mechanism Kit (included in M-1a Kit) * n.a.
1-100471   Use #3 - 202 (included in M-1a Kit) * n.a.
1-111019   PRR M1a Heavy Mountain Mechanism Kit * n.a.

  Cylinders 27" x 30"
  Firebox 79-7/8" x 125-15/16"
  Steam pressure 250 lbs.
  Tractive force 64,550 lbs.
  Weight of engine in working order 390,000 lbs.
  Weight of engine on drive wheels 271,000 lbs.
  Weight of engine on front trucks 59,000 lbs.
  Weight of engine on trailing trucks 60,000 lbs.
  Weight of tender 378,360 lbs.
  Length with Tender 15-1/4"
  Weight 2 lbs. 10 oz.
  Minimum radius 22"
  Power Bowser DC-71
  Drivers 72"
  Color Brunswick Green

  Note: To make Eight Wheel
    Tender, purchase #7006 Trucks
    and screw onto tender.

Assembly- Exploded View Drawings
(click on any image to enlarge)
Boiler & Mechanism Boiler

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