Jay Pat wrote:
Looking at the link, there are several images of the throttle valve and body.
These images are a rare look at the throttle valve.
I believe this design is such that if the throttle linkage inside the boiler became disconnected, the throttle valve would shut off the steam going to the cylinders. In other words, the locomotive would no longer have any power. This protects from a runaway locomotive due to linkage failure inside the boiler.
Pat
I did not know that, thanks for the information.