Wet rails and a heavy train might leave a conventional rod locomotive slipping the tires on the mountain grades, but for a geared engine like this Willamette, it's a piece of cake. Much like a Shay, the Willamette has three vertical cylinders, all of which are on the right side of the chassis. These cylinders turn a massive drive shaft, which is geared to every last wheel set on the engine's three separate trucks. It's the locomotive equivalent of All Wheel Drive. The gearing ratio ensures that while the drive shaft is spinning at a speed that will allow the engine to make a lot of power, the wheels are turning at a much slower speed, similar to a car in low gear. With all of that heavy machinery on the right side of the engine, the designers of both the Shay and the Willamette shifted the boiler to the left side of the chassis in order to maintain lateral balance. The resulting combination of evenly distributed power and low gear allows this type of engine to climb grades much steeper than any rod engine could ever handle. And yes, like most western steam engines, virtually all of the Willamettes were oil burners. Back in the day, they burned heavy bunker oil. Today, most preserved oil burners, like Rayonier #2, burn waste oil.