Invented to do the impossible, the Shay logging locomotive was designed to climb the steepest grades, swing around hairpin curves and negotiate frail temporary tracks. In addition, they had to haul incredibly heavy loads, from woods to mill. Power was all-important.
Unlike standard steam locomotives, Shays and the similarly designed Climax and Heisler engines are driven by direct gearing to each and every wheel. The smooth, even flow of power enables the engines to negotiate twisting mountain grades.