Athearn Genesis G1027 HO Scale 4-6-6-4 Challenger w/Oil Tender Union Pacific UP 3939 DC NYS&W The model features a winding

The model features a winding key

real-life mechanical principles which the builder can observe and appreciate both while building the model and while watching it run after it's been finished

operational flaps and more

but it can surely apply to numerous other quirky little problems (Monorails

Athearn Genesis G1027 HO Scale 4-6-6-4 Challenger w/Oil Tender Union Pacific UP 3939 DC NYS&W The model features a windingAthearn Genesis G1027 HO Scale 4 6 6 4 Challenger w Oil Tender Union Pacific UP 3939 DC ALCO constructed the first 4 6 6 4 locomotives in the world, numbered 3900 to 3914, for the Union Pacific Railroad in 1936. These huge engines were named the Challenger Simple Articulated, or CSA 1, class. The railroad received 25 near copies, classified as CSA 2, the following year. Unlike compound Mallet engines that crawled along with drag freights, the