The 2-6-6-2T Mallet, exemplified by Weyerhauser No. 9, was perhaps the ultimate development of the logging locomotive. Compact, powerful, and flexible, the type was ideally suited to pulling heavy loads over rough, sharply curved track. Geared locomotives like the Shay also possessed these traits, but could not make the speed of a rod engine. Baldwin Locomotive Works photo
Classic logging Mallet

