@@HotBulbEngines I genuinely need to see more about these engines and how they work, their history,mechanics. it is absolutely fascinating how machinery in this era was Built for Reliability and durability. Back then it was go big or go home and I wish in the modern day people would look back at history more to make things now.
It looks like he is trying to gauge the right moment to trigger the injection of fuel in order that the engine runs in the proper direction. The same method was used on Bolinder boat engines used on English canals. Judge it right and the boat instantly reverses. No need for a gearbox.
