3 cylinder shays

[dunoon]

While watching RFD-TV the other day there was a program about Cass RR.  I noticed that the locos have 3 cylinders,  it got my thinking, are they a regular compound, 1 high press.cyl.  and 2 low press. cyls or are they a triple expansion? 

Rich

[tree68]

I believe all three cylinders on a Shay are high pressure - much like a standard rod locomotive.  No compounding involved.  Look at the relative cylinder sizes - all the same.

[CSSHEGEWISCH]

Shays are all simples, compounding would be an unnecessary complication.  Three cylinders are used to smooth the effect of power strokes on the drive shaft with six power strokes per revolution.

[vsmith]

Indeed, Shays are noted as beeing the smoothest running steam locomotives of all time. The power transmission is constant...none of the rocking or hammering associated with rod locomotives, this and the greater adhesion and better abitilty of the trucks to track on the rails weight allows them to run over poorer track that the hammering of a rod engine might cause its own derailment. I've always though of geared locos being the forbearers of the Diesels, indeed the lessons learned from the success of the geared engines often showed in the designs of early diesel engines, and eventually to all of our modern diesels.