Simple Oscillating Steam Engine - Running and Testing

The engine needed some tweaking to reach a running state, this page details some of the likely problems.

The engine was assembled with some light oil on the mating surfaces.









Turning the engine over by hand revealed some stiff spots. In fact it could been seen that at one particular orientation of the crank the cylinder twisted slightly on the pivot pin causing a gap to appear between the cylinder and the frame.

To find the source of the problem first the axle/flywheel/crank assembly was tested independently in the bearing. This span freely by hand.

The piston was also tested in the bore and this was free to slide.

The piston pivot was free to turn.

So the cause was some mis-alignment between the crank pin and the piston/cylinder assembly. This was confirmed by the fact when the crank pin hole was expanded by 0.1m, the engine ran very smoothly.









Next the engine was put on an air test. Before connecting the air line a drop of oil was placed in the inlet port to lubricate the engine on the first stroke.

The engine ran but there was a lot of air leaking from the port face. Closer inspection showed that the cylinder was not square to the frame. Turning the cylinder over so it was upside down showed that the pivot pin was square but that the hole in the frame was not. Again this was adjusted by opening the pivot hole by 0.1mm, this allowed the spring to pull the cylinder square to the face.









After these 2 adjustments had been made the engine ran well on compressed air. It was noted that a lock nut would be required to stop the pivot nut undoing over time.

Another problem which was observed once the engine was runing on steam,  was one where the engine started and made several turns before stopping.
This was found to be due to a lack of lubrication.
Addition of oil to the cylinder helped the engine run continuously.

Steam oil is best or the thickest oil available as it can become very thin at elevated temperatures.

Adding oil to the cylinder










Click image to see a Video of the engine running on air.