Function over form. Sumpter Valley's 40-ton, 2-Truck Heisler covers its train with a steam blanket in the chilly air of a fall morning.
It is difficult to find adjectives to describe Heisler Locomotives. When Charles Heisler first started putting his designs to paper back in the late 1800s, beauty was definitely not high on his list of priorities. These engines were built for hauling logs off out of remote locations, where grades were steep and track was often pretty darn bad. Tractive effort was the primary design consideration. The Heisler utilized a two-cylinder steam engine, with those cylinders arranged in a V-configuration. You might say it was one of the first V-Twins. Those cylinders drove a central drive shaft, which extended down the longitudinal centerline of the locomotive. The drive shaft was, in turn, geared to the front wheel set of each truck. The rear wheel set on each truck was connected to, and received power from, the front wheel set via side-rods. Yup....it was a real piece of work. A particularly efficient piece of work at that. The Heisler design minimized the number of times that direction of motion was changed within the drive train, and in doing so, got more power from the cylinders to the track than its relatives, the Shay and the Climax. Heislers were also the fastest of the geared engines, which made them somewhat more versatile. Unfortunately, no machine is perfect and the Heisler had its shortcomings. That central drive shaft made the running gear a little tougher to maintain than on a Shay and it also limited the size of the firebox. The ride? Well, let's just say that a long day on a Heisler was like a long day on a Harley Davidson!