Author Topic: Steam chest question  (Read 395 times)

Offline Sky King

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Steam chest question
« on: June 06, 2019, 01:24:07 PM »
This applies to Elmer's #29 mine engine.

Since the steam chest is .250" high and the valve is .203" high, that leaves a gap of .041" between the valve and the top cover.
Question is ,,what keeps the incoming steam from pushing the valve up and steam escaping instead of flowing through to the cylinder passage???  I am thinking the nut holds it down but still curious..

Julian
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Offline cwelkie

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Re: Steam chest question
« Reply #1 on: June 06, 2019, 01:34:11 PM »
I think you will find that the supply steam fills the steam chest and helps hold the sliding valve down onto the sealing surface.  The valve diverts the cylinder exhaust to the exhaust port.

Online crueby

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Re: Steam chest question
« Reply #2 on: June 06, 2019, 01:50:31 PM »
I think you will find that the supply steam fills the steam chest and helps hold the sliding valve down onto the sealing surface.  The valve diverts the cylinder exhaust to the exhaust port.
Agree - sometimes with steam chests on the side of the engine (where the valve face is vertical) you may get some leakage past the valve when first starting up with low pressure, but as soon as some flow goes past it will draw the valve in tight, then the pressure difference from inside the chest to the exhaust port holds it there.

Offline b.lindsey

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Re: Steam chest question
« Reply #3 on: June 06, 2019, 01:54:23 PM »
Also important is a good flat and smooth interface between the valve and steam chest face (ports) to further eliminate any leakage.

Bill

Offline Sky King

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Re: Steam chest question
« Reply #4 on: June 06, 2019, 01:55:47 PM »
I thought that too, but with the exhaust port hole in the cover all of the pressure seems to be escaping via it... I get a LOT of air escaping out the cover port,,,
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Offline Sky King

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Re: Steam chest question
« Reply #5 on: June 06, 2019, 02:06:10 PM »
A little history behind this... I completed the engine and test ran it. I ran quite well even down to< 5lbs. I dissembled the valve parts to clean up and polish.
Now when I reassemble I cannot get  it to run..I even cannot get the cylinder to snap up and down by removing the valve rocker and manually moving the valve assemble by hand. If I take and inject air directly into the cylinder passage the piston will react... got me stumped
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Online crueby

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Re: Steam chest question
« Reply #6 on: June 06, 2019, 02:08:03 PM »
Exhaust port hole in the cover? The steam chest chamber should be filled with steam/compressed air, and the exhaust would come out the side of the steam chest base. Sure you dont have the exhaust/inlet ports reversed?

Offline b.lindsey

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Re: Steam chest question
« Reply #7 on: June 06, 2019, 02:10:35 PM »
Exhaust port hole in the cover? The steam chest chamber should be filled with steam/compressed air, and the exhaust would come out the side of the steam chest base. Sure you dont have the exhaust/inlet ports reversed?

That would be my guess as well...after all it did run the first time as you say. Easy fix if that is the case.

Bill

Offline Sky King

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Re: Steam chest question
« Reply #8 on: June 06, 2019, 02:12:37 PM »
on this engine (#29) there is no hole for exhaust in the side of the chest...It appears to be in the cover...  all of the others I have built were in the chest side,,,
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Online crueby

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Re: Steam chest question
« Reply #9 on: June 06, 2019, 02:15:11 PM »
Can you post pictures?

Online Jo

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Re: Steam chest question
« Reply #10 on: June 06, 2019, 02:27:58 PM »
On page 124 (second page of the instructions for this engine) Elmer writes: The steam connection on the Steam chest cover is for 3/16" tubing.

The exhaust is the hole on the side of the cylinder, which seems to have been tapped 5-40.

Jo
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Offline TerryWerm

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Re: Steam chest question
« Reply #11 on: June 06, 2019, 02:34:36 PM »
To add yet another drawing of the cylinder, showing where the exhaust port should be. If you apply air or steam pressure to this particular port it will blow right out the port in the steam chest cover because the pressure will lift the valve right off the seat.

Other than plumbing it backwards, did you by chance leave out the valve plate when you reassembled your engine?
Terry

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Offline Sky King

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Re: Steam chest question
« Reply #12 on: June 06, 2019, 02:42:44 PM »
Good Grief!! I feel so Stupid!!!!  I guess it happens when you don't work on it for a month,,, It took you guys to pull my head out of where the sun don' shine!!!  As soon as I switched ports it took off,,,
This is embarrassing !! Thanks for getting me back on the right track..
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Offline TerryWerm

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Re: Steam chest question
« Reply #13 on: June 06, 2019, 02:45:47 PM »
Don't feel embarrassed, Julian. It is an easy error to make. We've all had our share of brain farts, for lack of a better term!
Terry

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Offline b.lindsey

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Re: Steam chest question
« Reply #14 on: June 06, 2019, 02:53:00 PM »
Happens to all of us. Just happy you got it sorted in an easy way.

Bill

Online Jo

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Re: Steam chest question
« Reply #15 on: June 06, 2019, 03:48:31 PM »
Pleased it was easily sorted out  :)

Jo
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