- Geared Locomotives - Pacific Coast Shay (Lima
- The Shay geared locomotive was invented
by Ephraim Shay in 1879 to meet the
- needs of the logging industry. There
was a demand for a strong, flexible type of
- locomotive to negotiate steep grades
and tight curves. The Shay was first built
- with diminutive two cylinder vertical
steam engines and used on locomotives
- weighing twenty tons. A three-cylinder
vertical engines were soon added.
- The steam engine is mounted on the
right side of the boiler and the boiler is offset
- to the left to compensate for the
engines weight. The front view of a Shay shows
- the boiler being offset from the
centerline of the locomotive; however, it is the
- offset of the boiler that keeps
the locomotive in perfect balance.
- The connecting rods of the engine
are coupled to a crank shaft which is connected
- to the drive shafts by universal
and slip joints. Small pinions are attached to the
- driving shafts and engage the gears
on the truck wheels.
- The geared wheels are only located
on the engine side of the locomotive with
- two geared wheels per truck. There
are two trucks under the locomotive. In later
- years, one or two additional powered
trucks were used under an auxiliary tender.
- The Shay locomotives were built
by The Lima Machine Works (later called The
- Lima Locomotive Machine Works) of
- Shay locomotive near Antigo, Wisconsin, about
- Shay Locomotive near Aberdeen, Washington.
- The Iron Steed, a Shay geared steam locomotive
owned by the
- Mt. Tamalpais and Muir Woods Railway (a "gravity"
- Marin County, California.