Conversion of 4 Cycle Utility Engine to Steam

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vtsteam:
You can't get the valve timing I want from an oscillating valve. Hard to explain. I've worked my way through this with many drawings, and finally grasp it as a principle. The same thing happens with a conventional slide valve. The midpoints of the openings must be 180 degrees apart for a single slide valve or oscillating valve. I want an asymmetric opening sequence.

RussellT:
I have been wondering what would happen if you used a belt drive and a coupling rod - the belt to maintain drive in the right direction and the coupling rod to keep timing accuracy. It wouldn't be very elegant - but I can't help wondering.

Russell

vtsteam:
Russel, I'm certain that would work, as well. And where new cogged pulleys and belts weren't available, and there was a need to link two wheels, it's one more possibility.

In a sense that is what is happening with wheels running on a surface tied with a rod -- the surface enforces direction. I don't know very much about locomotives, and so maybe an 0-4-0 has the rods out of phase on opposite sides of the driven wheels, as well as the tracks to enforce direction. Railroad modelers will certainly know the answer to that, and I would like to hear about it.

vtsteam:
Just to give an update on progress, the cogged pulleys have arrived, and I've bored them out to fit the valve and crank shafts.

I've measured the belt length after checking with the head and head gasket installed. I hope I got that right so I don't have to use an idler. :zap:

I ordered the belt I think will work and it should be here in a few days.

I changed the valve design yet one more time :wack:, and so had to plug the ports I had already drilled. This head is definitely just a practice head!

I've re-drilled the ports, and am now filing them to a profile I think will work by hand. I haven't shaped the valve spindle itself yet, but that would be the next step. I'm a bit nervous about making a mistake doing that -- it would be very easy to get them 180 or even 90 degrees out of phase, or in reverse positions -- I'm having more trouble with orientation puzzles these days than I did 20 years ago! :bang:

vtsteam:
Milled the valve body today. As predicted I made one orientation mistake, but managed to save the piece as I'd left the stock extra long, and simply reversed it.

Still waiting on the belt. :coffee:

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