I bought an old model steam engine at an estate sale today, and I am
puzzled by the valve gear. There is no mechanical connection between
the crankshaft and the valve!

The steam chest has a shaft protruding from the fore and aft - these
will slide in and out. Haven't gotten it to run yet - I would like to
try to find out more about it before dis-assembling.

Can anyone fill me in on this beast?

TIA,
Wally