Horizontal miniature steam engine

I have finished making miniatire steam engine yesterday and tried running it on compressed air. It started moving at about 1bar and I was satisfied with the result. Later on today I tried testing in on actual steam. I opened steam valve at about 1.1bar in boiler and tried running it. Piston only had enough power to push the wheel for half a turn. Then I tried again at 1.5bar and 2bar and it didnt want to start running. Now Im thinking that I havemaybe made a bit to big cilinder and to big piston (8mm diameter). Should I make smaller piston maybe like 5-6mm diameter and smaller cilinder?

Thanks for replies,

Martin

Try it with less pressure and the nut on the spring would out. If you have the pressure too high it can lift the cylinder off the port face or you end up tightening the spring more to keep it in place which causes friction.

I usually air run at 0.2-0.3bar

Also check for a hydraulic lock if condensate is trapped in the cylinder

Edited By JasonB on 02/09/2023 13:40:38

I could make hole on the exit for the condensate that I can do, but I dont understand - my cilinder runs with very small friction. If I rotate it with my hand it can easily makes 3 turns. Im more looking towards the size of the piston hole, do you think that surface of piston could be the problem? As steam flow is slower than compressed air.

Martin

Edited By Dark Knight on 02/09/2023 13:59:08

Edited By Dark Knight on 02/09/2023 13:59:46

Edited By Dark Knight on 02/09/2023 14:00:32

If it stopped as in the photo on tdc or bdc it wont start again.

flicking the flywheel may help?

The steam may be too cold by the time it gets to the cylinder - insulate the pipework