Hi Daniel,
Looks like you are planning a three-cylinder oscillator to go with that boiler, and if that is the case, it would appear that the centre cylinder will have to be set up to work opposite to the two outer cylinders. Am I understanding this correctly?
https://youtu.be/p031jM1VrVA?si=NeINltzAvEKcQxzpTesting the engine with the boiler to be used. Yes the centre cylinder crank runs in the opposite direction to the two outer cranks.
Take care Tony.