Engines > Restoration of Model Engines

Help with a Little Husky ....... I think?

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Sanjay F:
More exhaust holes drilled, followed by drilling out the broken inlet and replacing it with a 3/16" union. I had to lap the cylinder and the valve guide as both those operations created some severe burrs.

It's together and moving smoothly with the aid of some oil and and the timing is guesswork, but it said open at TDC .....

https://www.youtube.com/shorts/vzuFJLMVn98

Sanjay F:
Wow! Beginners luck or what!!!! Check this out after a few spins ...................... ;D

https://www.youtube.com/shorts/IczXLPONNMY

What a fabulous noise these engines make ................ and I thought this was a scrapper, I think I'll make a little wooden base for it

Sanjay F:
I've cleaned her up and mounted it onto a wooden base; I'm pleased the Little Husky is running but still unclear how it works. I have read the Wikipedia page on Uniflow engines but that hasn't really helped me and the animated diagram on that page isn't helping in relation to this engine.

Can someone explain simply what is happening during the cycle of this engine please?

http://www.youtube.com/watch?v=ISbjzJXsd7o

Jasonb:
Based on them being meant to run on steam.

As the piston starts to decend from TDC the valve opens and lets in some steam which pushes the piston down.

About 2/3rds the way down the valve closes and the expanding steam continues to push the piston down further.

Just before BDC the exhaust holes are uncoverd and any remaining steam that has not fully expanded goes out the exhaust.

As the flywheel carries the piston back past TDC the exhaust closes

The piston continues to rise and any remaining steam will condense or be compressed by the piston as it nears TDC.

Flywheel carries piston over TDC and that trapped steam expands slightly and the cycle starts again with the valve opening

As steam is only coming in the valve and out the exhaust it is a Uniflow, unlike a single or double acting engine where the steam comes in and is than pushe dout via the same passage.

As yours has that extra slot in the valve and a bleed hole it is not quite a true uniflow as some of the steam goes back out the way the steam came in. But that does make it easier to run on air where you do not get the condensing that steam gives

PaulR:
Nice one Sanjay, yes they make a great sound!

I don't know how the valve works in your engine but in one of mine it's simplicity itself. In this image air flows in when the ball is lifted, pushes the piston down then exits through the exhaust holes when the piston is at the end of its stroke. As the piston travels back up some residual air is left in the cylinder which needs to be compressed to get the piston 'over the hump' to start the next cycle.

And yes, that Wikipedia page isn't great.

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