Trevithick

[Brian Rupnow]

The way that the 1/8" control rod attaches to the brass slider is somewhat complex. The rod is threaded into a rectangular "nut" that "floats" inside the towers on the back side of the slider. It has to be a tight enough fit that the nut doesn't rattle around, but loose enough that it doesn't bind on the slider. If it does bind at all, it may be enough to keep the face of the brass slider from making a perfect seal against the steel face with the ports milled into it. This can be one cause of air escaping past the slider. That is easily  corrected by a little creative file work on the nut or the slider.---or---It could be passing air because the face of the slider wasn't lapped against the steel. I find that I don't generally have to lap the faces, and if it is only a very small air leak, then running for half an hour will generally correct any differences in the faces. That video was made about five minutes after I had first assembled things and they were operating okay.  I will do a bit of detective work tomorrow and see what is causing the air leak.---Brian

[Brian Rupnow]

Today I completely disassembled the slide valve on the cylinder, and lapped both mating surfaces on a sheet of glass, beginning with 400 grit and finishing with 600 grit. It worked !!  I have never had to do that before on any of my engines. It's one of the ten thousand things I know about but haven't actually done before. The air leak is gone---or at least so gone that it is no longer audible.---Brian

[Brian Rupnow]

You don't have to be crazy to work here---but it helps!! Actually, what you see here is setting up the motor to run without the boiler. Since I can't get at any of the valve linkage when it is all inside the boiler, I will set everything up here and make all the adjustments required, then tear it down and reassemble it inside the boiler. --Sorta kinda like building a ship in a bottle.

[crueby]

Getting close, looking forward to seeing the TreviBrian engine going!

[Brian Rupnow]

All things cometh to he who waiteth---If he worketh like Hell while he waiteth!!! This is the Rupnow-Trevithick engine on it's very first run with the new slide valve. The 1 1/4" square aluminum bar and the two vices are there just to hold the end-plates securely so that I can run the engine without the boiler in place in order to make adjustments. I think my waterjet cut flywheel is too light, but I can alter that. It is very gratifying to me to see this engine run for the first time.----Brian
<a href="https://www.youtube.com/watch?v=BhVR7tLgEJ8" target="_blank">http://www.youtube.com/watch?v=BhVR7tLgEJ8</a>

[propforward]

Nice work Brian, great runner!

[crueby]

Great runneth!   

[Craig DeShong]

    

Wow!  Nicely done.  Anyone standing in the track is going to take a thrashing just before they’re run over   

[Brian Rupnow]

Hi Craig--I feel a bit like I've taken a thrashing myself just getting to this stage. Some engines just go together and run without a lot of drama. This one has been ahhh---difficult. It's going to look neat when I'm done, and I think I'm going to paint this one like I did the Stephenson's Rocket, but a different color.---Brian

[Mike Bondarczuk]

Hi Brian,

Have been watching this build from the outset and despite some initial stumbles you have persevered and finally arrived at a working solution, so full kudos for all of your efforts and also the descriptions of the various steps.

I shall be starting a build of one of your earlier works which is the simplified beam engine I believe based on Julius's drawings.

Mike

[Brian Rupnow]

Hi Mike--Good luck with the engine. it was based on an Elmer Verbourg design.---Brian

[Brian Rupnow]

Todays game plan got changed a bit. My waterjet guy was able to make my two steel rings yesterday afternoon, so today I drove over and got them, brought them home, drilled and tapped them and mounted them to the existing flywheel. It's been a cold dreary, rainy day here, but I was glad to get out of the house for a while. The flywheel was originally a piece of 3/16" mild steel plate. I have added a 1/8" steel plate to each side of the rim to make it a little heavier, in hopes that this will let me run the engine slower.

[Brian Rupnow]

This video shows the engine running with the extra plates added to the flywheel. I'm very happy with this result. The engine will run much slower now.---Brian
<a href="https://www.youtube.com/watch?v=Bwn5rP4Oxwo" target="_blank">http://www.youtube.com/watch?v=Bwn5rP4Oxwo</a>

[crueby]

Very good!!  I wonder what it would do with the same pressure but putting a needle valve inline just before the steam chest to restrict the flow - have gotten good results with that on some engines to slow them even more.
 

[Brian Rupnow]

There are two ways to control the speed of these engines. One is to control the pressure like I am doing. The other way is to hold a high pressure and control the volume of flow with a needle valve. I think the high pressure and needle valve give more control. I have a bank of needle valves here that I used at a steam show to control a bunch of engines about 8 years ago. I may try running my feed hose thru that and see what the results are.