Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

You have an interesting engine!

If you remove the steam chest cover you will be able to figure out the porting.

Regarding a gear driven cam or eccentric shaft, the design is an older one.

The New England Wireless and Steam Museum has a Herreshoff Triple Expansion Marine steam engine built 1904. These were originally designed and built as torpedo boat engines in the late 1800's.

Here:
https://newsm.org/steam/herreshoff-triple-expansion-steam-engine-1904/

Gil