by John

Just a quickie.

I am close to running my triple expansion steam engine, and I am thinking about what will be required to set the valve timing.

The high and low pressure cylinder valves can be visualised by removing the valve steam chest covers and should not be too much of a problem to set.

However, the intermediate valve steam chest is buried in the middle of the engine, and can be visualised only by close to totally dismantling the engine.

So I have made a protractor which has the 360 degree circle divided into 120 degree sectors, and single degrees, with 5 and 10 degree markers for easy counting.

The protractor will be mounted on the end or the crankshaft using 6 bolts located into 6 precisely drilled and tapped holes.


The protractor.  100mm diameter aluminium plate.

When the high pressure cylinder valves are set, the degrees of rotation of the crankshaft will be noted, the crankshaft rotated 120º, and the intermediate cylinders valves set to the same settings.  At least that is the theory.  I am sure that it will be more complex than that.


The triple expansion engine with the protractor attached.

I just wanted to show the completed protractor.  I have not stamped or engraved the degree numbers, because they would need to be in groups of 120º, and the protractor would therefore be a single use item.