The Travel Town Museum in Griffith Park, Los Angeles, has a special treat for visitors. On display is a three-truck Shay built by the Lima company in 1922. Unfortunately, this one is not operating, but it is still work viewing up close.
The Shay design was not intended for speed. Its main purpose was to haul extremely large loads, and that is why they were very popular with logging companies. Many Shay engines ran through the mountains for the American West pulling cars loaded with logs.
The Shaw design featured a gearing system that provided power to the trucks. Each truck swiveled independently of the others, which meant that the engine could operate on very tight turns. Power was delivered to the wheels on the trucks by vertical drive rods instead of the horizontal rods of the “traditional” steam locomotives.
Seeing one of these engines at work is a true sight to behold. The vertical driving rods activating the horizontal geared shafts look like they are going to fly off the engine. Parts spin, turn, and fly back and forth with a great deal of huffing and puffing. Despite all the animation, the Shay does not move very fast. The contrast between huge activity and little speed is one of things that makes this sort of machine interesting.
You can learn more about this engine on the Travel Town Web site at www.laparks.org/traveltown/locomotives/camino-placerville-and-lake-tahoe-2.