Model Trevithick Dredger Engine on Steam. Fail. Well, maybe a bare pass.
by John
Well, I was really not expecting this.
After all, the engine was running well on compressed air at 30psi, and the burner appeared to have a good flame.
And Stuart was coming to be involved with the big event. So nothing could go wrong!
I set up the iphone on a tripod. Checked the light. Oiled the bearings and slides. Filled the boiler. It takes 2 litres of water. And hooked up the propane. when Stuart arrived I lit up the burner, and sat back to see how long it would take to raise steam.
Some steam leaks were expected, on this first steam run. Leaks don’t show on compressed air, unless they are severe. As the water heated up, some leaks appeared. The water feed clack valve and the sight glass were bad. The clack valve just needed some goo. Later I disassembled the sight glass, and cleaned the valve, with some improvement, but more work needed. Or a new sight glass valve. A couple of other trivial leaks were easily fixed.
So we watched the clock, and checked the temperatures. Ot took 20 minutes to start raising steam. That is a bit slow. Eventually it reached 20psi, but the pressure refused to go any higher, despite fiddling with the gas and air controls.
At 20psi, I opened the throttle and gave the flywheel a swing. You can see the result.
After that, we let it cool down and fixed the clack valve leak. The sight glass valve leak was looked at later, but could not be fixed simply.
The burner flame. A bit feeble. A bit yellow. And occasionally blown out by the cylinder exhaust gas puffing into the chimney. Stuart says that I need to angle the cylinder exhaust gas upwards in the chimney. Apparently Trevithick did not do that on the full size models, but perhaps he should have.
The burner was definitely not up to the job, so in this last video, it got some assistance.
It does go! Just needs a few tweaks. Lovely sound.
johnsmachines 
Looks like you are coming down to the wire John. A job well done!
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Nice run John,
As I expected the bunner has not enough spirit to keep the boiler on pressure, beyond that it need to heat up a lot of material and keep it warm, isolating the boiler will be even an improvement.
I bigger hole in the nozzle and bigger airholes will power up the burner,
If that is not enough maybe a second firerod unther the caremic stone.
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Congratulations on the first live steam operation of your engine.
A few details, some prettying up, and it will be quite handsome!
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Get it working properly first. Then pretty up. Mainly need an adequate burner. John
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I don’t know why my “Congratulations on the first live steam operation of your engine.A few details, some prettying up, and it will be quite handsome!”reply came across as anonymous, but I sometimes have trouble with this site and it’s probably my fault.
The burner problem will be easy to fix. That’s the reason I asked about the boiler capacity, etc. a couple of weeks ago. I’m pretty sure a slightly larger gas orifice with sufficient air will do the trick. Wish I could just drop in and have a look.
Cheers, Richard
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I wish that “someone” who knows about gas burners would drop in! But check out today’s post. I think that I am winning. The answer was not just about gas and air flows.
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Thought of you when I saw this. I’ve been following the restoration of the Union Big Boy #4014 for a few years. I want to go see it running. You may find the story interesting; this is but a tease.
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Thought of you when I saw this. I’ve been following the restoration of the Union Big Boy #4014 for a few years. I want to go see it running. You may find the story interesting; this is but a tease.
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Looking back at your posts, I can’t figure out how you control primary or secondary air into the combustion system.
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No air control. Just gas control. It might benefit from air control too!
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