Author Topic: Trevithick  (Read 11826 times)

Offline Brian Rupnow

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Re: Trevithick
« Reply #45 on: August 29, 2020, 08:35:06 PM »
I have been asked how the Trevithick compares size-wise to the Stephensons Rocket. It's roughly in the same ballpark, but far from being identical.

Offline JULIUS

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Re: Trevithick
« Reply #46 on: August 29, 2020, 09:50:55 PM »
Brian

Attached are the drawings which I mentioned before.
This steam engine uses a 4 port valve
I have a video of how this valve works, but I have to send this to your e-mail address because it is too large to put it on this forum

Julius

Offline Brian Rupnow

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Re: Trevithick
« Reply #47 on: August 30, 2020, 12:00:32 AM »
I have been moving the piston and steam valve around on my CAD system to see if everything makes sense. It seems to, with the exception of one cylinder port and I have asked Julius to check the position of the one hole in question. I have also asked again if anyone has actually built this configuration that he has drawn. Once I am completely happy with what Julius has sent me, I will start modifying it to give the bore and stroke that I need for my Trevithick model. Julius makes beautiful drawings. I have been badly spoiled by the practice in Canada of putting a detail of each part on it's own individual drawing. I've had to do some serious hunting on his drawings to find the parts I need to model.

Offline Brian Rupnow

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Re: Trevithick
« Reply #48 on: August 30, 2020, 12:09:33 AM »
Julius sent me this today, an animation of how the four way rotary steam valve is operated on the original Trevithick engine.

Offline sbwhart

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Re: Trevithick
« Reply #49 on: August 30, 2020, 12:39:20 PM »
Is this what your building Brian


I've actually bin to a Travithick day and seen Puffing Billy come up the hill in Canborne and seen the steersman fighting to keep control of it:- Scarry  :ShakeHead:

Her's another one bit longer and with more detail


Stew
« Last Edit: August 30, 2020, 12:46:00 PM by sbwhart »
A little bit of clearance never got in the way

Offline Brian Rupnow

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Re: Trevithick
« Reply #50 on: August 30, 2020, 12:53:35 PM »
I am building the Pennydaren which can be seen in this video.
feature=emb_logo

Offline fumopuc

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Re: Trevithick
« Reply #51 on: August 30, 2020, 03:08:53 PM »
Hi Brian,
may be this is of interest for you to watch.
A member of our German forum has build one some years ago.
https://youtu.be/5i3S_dqMMoM
Here are two videos from this summer, he has installed his own tracks in his garden now.
https://youtu.be/IuQbT753kmo
And a ride around one or more laps.
https://youtu.be/OaFAzVg9KXY
And here the model of the steam wagon, also build by him.
https://youtu.be/FNfDD81BOnY
« Last Edit: August 30, 2020, 03:16:17 PM by fumopuc »
Kind Regards
Achim

Offline Brian Rupnow

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Re: Trevithick
« Reply #52 on: August 30, 2020, 04:27:38 PM »
Fumopuc--great videos. The engine seems to perform very well.---Brian  I am going a bit batty this morning, checking to see that the correct ports are covered and uncovered in the cylinder as the piston and valve move back and forth in the cylinder. This is the kind of thing that you really want to get right on paper (or computer) because the next phase, building it in metal gets costly and time consuming if the ports aren't where they should be.

Offline Brian Rupnow

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Re: Trevithick
« Reply #53 on: August 30, 2020, 11:50:07 PM »
It's been a long and interesting day. I have taken the cylinder that Julius sent me, changed the diameter and the stroke length, eliminated some of the seals that crossed ports in the cylinder and changed the piston rod size. All I can do now is hope that I got it right and build it. I don't have a "safety net" of other designers and engineers to check some of this stuff for me. I won't build anything else on the project until this cylinder is finished, because this cylinder is the heart of the whole operation. There are no cams or eccentrics on this engine. The spool valve inside the end of the cylinder replaces all of that. There are seven ports on the sides of this cylinder. I am going to solder short lengths of small brass tubing to the outside of the cylinder at the ports and use flexible nylon tubing to connect them all. It will all be hidden inside the body of the Trevithick boiler.  I will keep you posted as this develops.

Offline Art K

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Re: Trevithick
« Reply #54 on: August 31, 2020, 03:24:30 AM »
I can totally understand fighting to steer that up the hill, it does look like steel shod wooden wheels & no suspension, and a tiller to boot. I wouldn't want to be in his shoes, he's a brave man!
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline Brian Rupnow

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Re: Trevithick
« Reply #55 on: August 31, 2020, 03:34:31 PM »
This morning the new cylinder is completely designed. I have moved all of the ports around into the bottom 60 degrees of the cylinder so they can be connected with flexible tubing. I have also redesigned the cylinder and end caps so that there is no welding or silver soldering, because I am concerned about warping the long cylinder from heat related issues. The cylinder body is now made from much heavier wall material so that I can tap the ports for 1/4"-20 threads, which lets me screw in the hose barbs with a bit of loctite so no heat is involved. I got some rather disturbing news this morning from Julius. He doesn't know if anyone has ever actually built this cylinder or not. To my knowledge I have never seen one like this myself. I don't care to be a guini pig for untried designs that haven't been built successfully by somebody else.


« Last Edit: August 31, 2020, 03:43:48 PM by Brian Rupnow »

Offline michaelr

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Re: Trevithick
« Reply #56 on: August 31, 2020, 04:03:42 PM »
Hello Brian,

This site may be of interest to you, it's a build log for a model Trevithick Dredger Engine which has a similar cylinder/valve arrangement only it's a vertical cylinder.
https://johnsmachines.com/2019/02/16/a-tour-of-the-model-dredger-engine/

Michael.

Offline Brian Rupnow

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Re: Trevithick
« Reply #57 on: August 31, 2020, 09:20:26 PM »
Thank you Michaelr---I haven't had time for an in-depth look at what you posted, but I will certainly have a look at it later today. I have decided to go ahead and build the cylinder even though nobody knows if it has been built before to Julius' drawings. If it works, then Hooray, I'll be a hero. If it doesn't work, I will be able to salvage most of it to work with a more conventional valve system. I picked up the material for it today. The main cylinder body is going to be made from hot rolled steel. This is not something that I would normally use, but since the engine will be ran on compressed air it should be okay. I generally would use grey cast iron for a cylinder if it was for an i.c. engine or driven by steam.


Offline Brian Rupnow

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Re: Trevithick
« Reply #58 on: August 31, 2020, 11:48:47 PM »
And the ugly 1 1/2" piece of hot rolled has yielded a nice cylinder. 1.375" o.d. x 0.75" i.d. x about 5 1/2" long.    O.D. machined with brazed carbide at 680 rpm, inside drilled and reamed to 0.75". Hot rolled steel is such a nice steel to machine. I can get a much nicer surface finish on hot rolled than I can on cold rolled. Tomorrow I have about a billion holes to drill and tap.

Offline crueby

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Re: Trevithick
« Reply #59 on: August 31, 2020, 11:53:09 PM »
Moving right along! Watching along here!   :popcorn: :popcorn: