In 1930, the celebrated success of the M1 Mountain-type locomotives prompted the Pennsylvania Railroad to order 100 more locomotives of the 4-8-2 wheel arrangement. The new locomotives became the M1a class and had a longer wheelbase than the M1's due to the addition of the Worthington feedwater heater. They also received new larger tenders, class 210F75, which became known as the coast-to-coast tenders.
The first 50 M1a locomotives, #6700 - 6749, were built by Baldwin. The Juniata Shops, which became knows as the "Altoona Works," built the next 25 M1a's numbered 6750 - 6774, and the remaining 25 M1a's were built by Lima and were numbered 6775 - 6799.
Starting in 1946, 41 of the M1as received further improvements by increasing the boiler pressure and adding circulators to the firebox. The improved M1as became the M1b class. The best way to tell them apart is to look for the circulators on the firebox just above the running boards. The circulators are those round objects in a diagonal line that look like wash-out plugs.
The PRR M1a/bs were considered to be the finest of the PRR's steam locomotives. They were designed as dual service locomotives, hauling passenger trains and also saw duty in general freight service. And in the end, they even hauled the heavy ore trains, which there were not originally intended to pull. They did it all in style!
- Paragon3 Sound & Control System with Rolling Thunder
- Integral DCC Decoder with Back EMF for Industry Best Slow Speed Operation in DC and DCC
- Motor Type: 5-Pole Can with Skewed Armature & Fly Wheels
- Authentic PRR M1a Sounds
- Premium Caliber Painting with Authentic Paint Schemes
- Prototypical Light Operation with Golden White LED Headlight and Reverse Light Jewel
- Beautifully Detailed, Accurately Modeled Locomotive
- Separately Applied Details such as brass bell, grab irons, and ladders
- Constant Intensity Directional Lighting
- Locomotive Composition: ABS plastic with Die-Cast Chassis
- Tender Composition: ABS plastic with Die-Cast Chassis
- Locomotive Length: 6.5 inches
- Tender Length: 3.8 inches
- Couplers: Microtrains #1015 compatible
- Recommended Minimum Radius: 9.75 inches