The search for the perfict valve.

[WSMkid]

Hi all. I'm a Sr. at a small high school in southeast Ks. 5 or so years ago my dad got a ~16x54 leath and a ~49x16 mill. In the past few years or so I have gotten back into air/steam engines. about a year ago I turned out my first osolateing (I'm a terable speller I'm sorry) engine in about 6 hrs from plains in the 3 book set of Rudy Kouhoupt's. After that I "tryed" to buld a vertical engine with a spool valve out of the same plains.. to small so I scaled up 2x and this one really runs good. I had been workin on this one for probly 6mo... got out of the mood with the 100* temps and no A/C in the shop. Next I would like to buld a BIG walking Beam of my own desin. Growing up in the oil field you know how to make things work(mostly why I am going to PSU for Eng. tec.)

Back to the walking beam...
I cant deside what type of Valve I want to use. Valve's are the only thing that scare me about engines. I'm ok with the spool but the one I have in my 2x vertical is allready starting to leak bad and has less than 2 hrs on it. I know I didnt get a very good finish on the valve body and that it is just running its self in but I would still like to know more options.

The sliding chest type valves seam to be a pain to buld. IMO
So I guess I'm just asking every ones opinon on different ways to go..

Some spects on the beamer.. as of now.

bore : 3"
stroke: 3"
fly wheel:12" (thinkin about usin a shive off of the gear box on a pumpjack)
will probly stand 3' tall

base will probly be 18"x 36"
I would like to buld a small duplex water pump for it after this is all said and done.
buld should start 2 weekends from now and hoping to have it done befor Xmass.

I'm loving this site I have been creepin for the past 3 days and have spent probly 10 hrs on here.

Thank you all!

GJ

 

[Jasonb]

I'd put a slide valve on it, with that size cylinder and the mass of metal there is a risk of condensate so having the valve able to lift off the face to stop it hydralic locking is a big advantage, built right you should get 100s of hours use from it so worth spending the minimal extra time on it now.

J

 

[WSMkid]

All my engines are ran off of air. Its just to easy to grab the air hose and a reg. and watch them run. Does any one have drawings for a slide valve I could scale up and use on my buld? Im plaining on it being double acting so ill just run 2 valves on eather side of the cylinder and have them act independently oorr I could have two valves in one chest..hmm

Thank you all for the help!

GJ

 

[Maryak]

Even if it's double acting you still only need one valve per cylinder on a steam engine as below

Best Regards
Bob

 

[Jasonb]

Yep one valve will be so much easier to time and a lot less work as you only need one eccentric & strap, one rod, etc.

J

 

[black85vette]

You might want to go read through Brian's build of the popcorn engine. He has plans, 3D model and a description of the build. It is a double acting horizontal and you can see how the valve / cylinder work. Link is here:

http://www.homemodelenginemachinist.com/f31/brian-does-popcorn-15155/

Here is an animation of that valve action;

http://www.animatedengines.com/locomotive.html

 

[WSMkid]

Wow.. I feel dumb not knowing how slide valves worked.. I had my own Idea but I was waaay off. Thank you and I reckon that will work. guess I need to spend some time on wild fire tonight and get this baby modeled!

Thanks to all!!

GJ

 

[WSMkid]

Welp its 12:05 here and I after the 3rd try I think I finly have my valve chest modeled but I dont know how to put a pic form wild fire to here.

specs are

4" long
3" tall
2" deep

Cavity is 1.5" deep

ports are 3/8" .76" from eachother on centers
slide rod will be .25"

Thanks for then help every one!
Very ready to start this buld.

good night to all late night bulders
GJ

 

[WSMkid]

This is about the only drawing I'm going to use on this buld. I'm hopping I can get it all from my experance. Now I just need some stock..

GJ

 

[Jasonb]

If that is your valve chest then a few comments

The wall thickness is very thin, how will you get the studs in to hold the cover.

You have made no allowance for a stuffing gland around the valve rod.

You have no support for the tail end of the valve rod.

It is usual to have the exhaust passage larger than the inlet passages, about double is a good starting point

J

 

[Tin Falcon]

Hey kid IMHO build a couple of models with a known design or at least basses on a known design. steam engines have been around for a hundred plus years. Lots of info in archives. and old books. and as far as a 3 in bore that is a mighty big model . I suggest 3/8 to 1/2 bore for most people to start on the large machines you have bump it up to 1 to 1.5 if you need to.
are you aware of the laws of scaling ? if you take an engine with a 1" bore and it weighs 10 lbs the scaled up model will weigh 270 lbs in 3" bore. liniar measurements are proportional volume is proportional to the cube.
take an old set of drawings and redraw with your cad .
Tin

 

[WSMkid]

Tin Falcon this will be my 3rd buld, and yes she is gonna be big. I have been workin on and around our machines for probly 5 years or so and have probly 1000hrs on each as a guess. I would going to buld the beamer out of Rubbys but I really didn't care for the desine (not saying it was bad some thing about it didn't click) so I decided I would do what i really wanted to do and that was desine my own version I have never been one to like to follow plains. When I was 5 I bult a pulling unit like my dads using my Knects... loved thows things. I'm just wantin somthing that I can test my skills I guess.

Thank you for the words thow.
GJ

 

[WSMkid]

My plain for the studs was to bolt to the cylinder threw the cover and chest. Althow in my head (so far) I'm going to have my govn' mounted to "the cover", so my cover will not really be a plate it will be more of a reg/ disturbution block mounted to the bed and the cylinder. In this block I'm aslo planing on having an automatic oiler, have a small ecentric ran pump pushing threw a jet. That might be for latter thow.

I thank both of you for making me look back. Measure twice and cut once!

Thank you

GJ