Also known as a "Walking Dudley" This was the first attempt to climb short but steep grades. The Shay, Heisler and Climax put it out of business in short order. Lines would be secured at the top of a grade and then wrapped around the capstans to drag itself up the grade. there were several down on the Columbia. Louis Saldern's KM Mountain Logging had one. It's photo is is several books about early logging.