You can read the full article on this locomotive at brickmodelrailroader.com
Norfolk & Western Railway, Y6b class 2-8-8-2 Steam Locomotive
The Norfolk & Western Y6b class was one of the most efficient steam locomotive designs ever built. With a starting tractive effort in simple configuration of 152,206 pounds, and in compound mode, a tractive effort of 126,838, the Y6b was capable of producing more tractive effort per pound than any other locomotive built including the C&O H-8 "Allegheny" and the Union Pacific "Big Boy",
My LEGO model of 1218 features working Baker valve gear, and is powered by two Power Functions XL motors in the tender driving through the tender trucks.