I am thinking that it is simpler than that. First the locomotive is charged with 1000psi air. There is a regulator that only allows 150psi to the cylinders no matter what. The tractive effort is a product of pressure against a known cylinder size. I think that Kelly is also correct in that this is the size cylinder space that they could work with and so used two cylinders per side to get the required sq inches of cylinder surface area.

> I am thinking that it is simpler than that.
> First the locomotive is charged with 1000psi
> air. There is a regulator that only allows
> 150psi to the cylinders no matter what. The
> tractive effort is a product of pressure
> against a known cylinder size. I think that
> Kelly is also correct in that this is the
> size cylinder space that they could work
> with and so used two cylinders per side to
> get the required sq inches of cylinder
> surface area.

Oops. I deleted the message this posted to rewrite my original posting (new software will fix this problem ).

The regulator would work, but would be fairly maintenance intensive at the volumes of air required by the working engine. The two valve method would somewhat simpler from the perspective of reliability.

Maybe someone knows how the really work!

Ed

ff1044@aol.com