Chelk it out

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csonics
Anne from Little Britan
Anne from Little Britan
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Chelk it out

Post by csonics » Wed Nov 18, 2009 4:05 pm

Posted on behalf of 87gn@tahoe:

87gn@tahoe
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Joined: 23 Feb 2009
Posts: 148
Location: South Lake Tahoe, CA
Posted: Sun Jun 14, 2009 11:30 am Post subject: Chelk it out
My Father's birthday present from my girlfriend and myself.

New block from Robert Scripps for the engine in my father's boat (Sitting outside curing for a bit).

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This is also a Scripps piece, though as you can see, this one has a inside admission piston valve on the HP and is one solid casting with the steam ports cored in. This is opposed to the slide valves, seperate cylinder castings, and heavy plate below the cylinders on the "version 1" engine in our boat currently.

It's a heavy duty casting at about 100lbs , but it will last 100+ years more than anything else out there.

Robert Scripps designed this casting to work with everything from his original engine, so it will be a "bolt on" piece, so to speak.

Dimentions are 3.5"&5"x4"..

Trying to convince my father that we should go with a Piston valve on the LP, or at the very least, a balanced slide valve.

Wes
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Wesley Harcourt
-S.L. Wayward Belle (Mr. Grosjean was/is a genius.)
-S.L. George H. Sandin (Father's boat. Cut my teeth on that one.)
-'64 Buick Riviera
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Maltelec
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Joined: 23 Sep 2007
Posts: 156
Location: Cumbria, UK
Posted: Mon Jun 15, 2009 12:37 am Post subject:
A piston valve on the LP is always an odd one to argue. True a piston valve works better generally than a slide valve, but at the same time a slide valve "should" push off the face if you get water in the LP, which is more common than in the HP. Its a good idea to have a relief valve on the LP anyway.

A balanced slide valve is a good idea as long as you design it correct.
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I've got the vehicle , just need the boat.
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87gn@tahoe
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Joined: 23 Feb 2009
Posts: 148
Location: South Lake Tahoe, CA
Posted: Mon Jun 15, 2009 10:46 am Post subject:
We were going to go with a relief valve on the HP and if we went the PV route on the LP, a relief there as well.

Trying to convince him to go with something other than the conventional SV on the LP will be a chore in and of itself. I had to get the block for his birthday because he is so set in his ways... Before I bought it, he hmmned and hawwed for months about getting the block.. I finally just sent the cheque and had it sitting outside the garage on his birthday.

I don't blame him though.. I'll probably be just like that when I'm his age.
_________________
Wesley Harcourt
-S.L. Wayward Belle (Mr. Grosjean was/is a genius.)
-S.L. George H. Sandin (Father's boat. Cut my teeth on that one.)
-'64 Buick Riviera
-'65 Buick Special WAGON
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fredrosse
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Joined: 26 Sep 2007
Posts: 19
Location: Philadelphia, PA USA
Posted: Sat Jun 27, 2009 3:21 pm Post subject:
A balanced slide valve can be made with an "O"-ring mounted on a circular riser machined on the slide valve, and mounted between the slide valve and the steam chest cover plate. With a good surface finish the "O"-ring will last ok. If it fails, then you are just back to an ordinary slide valve setup (unbalanced) until you can replace the "O"-ring.

Some recommend Viton, I am using Aflas "O"-rings, as they are more suitable for dynamic motion in steam. The best is probably an "O"-ring that is Teflon encapsulated, but they are costly.
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mcandrew1894
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Joined: 11 Oct 2007
Posts: 149

Posted: Sun Jun 28, 2009 8:17 am Post subject:
You can go with a piston valve without the relief valve if your disciplined with opening your drain valves after any stop. Sabino has done that for years.

My engine will give you warning signs of when there's water which is usually enough time to crack a drain valve.

The problem with the piston valve on the LP is you would really like to go to outside admission and with a piston valve, you need a rather complicated reciever pipe, or a hollow piston valve. Both can be a pain to build. A balanced slide on the other hand requires neither, and will lift if there is a problem........

My engine has a split receiver and a piston valve.....works well but more complicated.....

Dave
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steamboatjack
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Joined: 01 Oct 2007
Posts: 39

Posted: Thu Jul 02, 2009 1:55 am Post subject: balanced slide valves
a balanced slide valve of the simple o-ring backed type has very little room to lift off the face to relieve water pressure, and in my experience are not too successful. below is a design I am using on my new engine although I must stress it isn't built yet! too many projects on the go!!!!!

Image

the valve buckle is circular although the valve body is guided on each side so does not require a tail rod etc.
the two parts use an o-ring seal but the balance face uses water grooves, the respective areas are about 1 to 0.6, if you have a total balance you may find the valve face may "lift off" at compression.
There will be a light spring to maintain the faces for starting.
Regarding hollow piston valves (outside admission) these are easy, and work well, however I would imagine there is a lot of heat loss though the thin body of the valve. I have one fitted to Grayling's H.P. cylinder.
regards
jack.[/img]
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fredrosse
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Joined: 26 Sep 2007
Posts: 19
Location: Philadelphia, PA USA
Posted: Thu Jul 02, 2009 6:37 am Post subject:
I have made inside admission piston valves, with a hollow core for exhaust passage. These could also be used for outside admission, but in my application I wanted low pressure on the packing gland.

The core was made with double wall, to cut down on the heat transfer between the exhaust and live steam. A gap between the inner and outer sleeves of just a few thousandths of an inch will reduce heat losses across this surface very significantly.
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mcandrew1894
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Joined: 11 Oct 2007
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Posted: Fri Jul 03, 2009 10:09 pm Post subject:
Hi Jack!

Long time since we spoke! How are you!

Ok you say your hollow piston valve is easy to make......if you say so I believe it......but do show us mortals would you?

You wouldn't happen to have a picture of Grayling's valve would you?...and perhaps a brief description?

Dave
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steamboatjack
Urchin


Joined: 01 Oct 2007
Posts: 39

Posted: Sun Jul 05, 2009 11:07 am Post subject:
sketch of the item, I did try a few ideas before this but I wanted to have wearing surfaces which were easy to renew. the valve consists of a bobbin (bronze) with two cross shaped end pieces (stainless steel) and two renewable bushes (bronze) forming the valve lands these have the usual water grooves (not shown). The only problem is that its not "floating". Piston valves are best when made to float radially so they wear evenly and are not influenced by the spindle.

regards jack
Image

mcandrew1894
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Joined: 11 Oct 2007
Posts: 149

Posted: Sun Jul 05, 2009 4:59 pm Post subject:
Brilliant! Thankyou Jack!

I agree, the floating part is important, but not absolute as evident by your lovely boat!

Warm Regards,

Dave
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mcandrew1894
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Joined: 11 Oct 2007
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Posted: Sun Jul 05, 2009 5:41 pm Post subject:
Fredrosse,

Yes I made my LP valve outside admission also, My valves are just simple spools made in three pieces, so that the upper and lower valves float with respect to each other. That works great but makes the receiver plumbing a bit problematic. To solve it, I copied a design by Seabury for a 100 HP triple expansion engine that I participated in the restoration of. The receiver splits at a T just before the LP and is attached via 180 degree flange at the top and bottom of the LP valve. There are 5 bolts around the flange at the LP valve with a 6th long threaded stud passing through the center of the T. The T has a face seal on both top and bottom sides that are brought together by the this through bolt.
A rather ugly sketch....
Image
This design is effective and allows for a free flow of steam, but is a bear to make as the stackup must be made well.
I used Viton O-rings for the seals and my receiver fittings were fabricated with silver solder...

Dave
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