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Gallery, Projects and General => The Design Shop => Topic started by: sbwhart on August 17, 2011, 12:07:20 PM

Title: Triple expansion engine valve arrangement
Post by: sbwhart on August 17, 2011, 12:07:20 PM

I've been doing a little research into a triple expansion engine I saw in one of George Watkins books.
 
The high pressure cylinder has a Corliss valve arrangement, and the low pressure a slide valve arrangement I reasonably understand these arrangements: but the intermediate is described as follows :-
 
"The intermediate cylinder is fitted with two slides and cut off plates, worked directly by eccentrics. These valves can be regulated to cut off earlier or later as required to equalize the amount of work done by the respective cylinders. In order to facilitate the adjustment of the valves the cut off spindle has a screw index and wheel"
 
I can understand why they would want to regulate the steam flow between the cylinders, but I can,t get my head round the how,  :scratch: I've got a picture of the engine and they are two valve rods going into the intermediate valve chest.
 
Can any one shed a little light on this
 
Thanks for your help
 
Stew

Title: Re: Triple expansion engine valve arrangement
Post by: sbwhart on August 17, 2011, 05:09:36 PM

Got it sorted  :smart:

from her http://www.archive.org/stream/steamengineprinc00crofrich#page/28/mode/2up

Page 28 fig 34

Stew

Title: Re: Triple expansion engine valve arrangement
Post by: doubleboost on August 17, 2011, 05:25:31 PM

Hi
Stew
You going to build one  :drool: :drool: :drool: :drool:
John

Title: Re: Triple expansion engine valve arrangement
Post by: sbwhart on August 17, 2011, 05:57:30 PM

Hi John

I've got one sketched out, got most of the how too issues sorted in my head, need to translate them into a drawing that will take a little time as I want to start doing something on the loco.

(http://i431.photobucket.com/albums/qq32/sbwhart/Potty%20Over%20Crank%20Wall%20Engine/scan0003.jpg)

Also got a 1/3 scale popcorn engine sketched out that I've started to draw up.

In the mean time I've got my mill in bits swaping the Y DRO over to right side so that it doesn't get in the way of the power feed.

I've really got an itch from the triple, got loads of info from the English Heritage archive, but I will have to sort out copyright issue with them as I think it would make a good subject for an article.

Stew

Title: Re: Triple expansion engine valve arrangement
Post by: HS93 on August 17, 2011, 07:29:36 PM

YEA Go Go Loco   :lol: :lol:  no realy lets have some more of your loco please  :nrocks:

Peter

Title: Re: Triple expansion engine valve arrangement
Post by: Stilldrillin on August 18, 2011, 03:38:07 AM

Stew.
Don't you think that little loco has been ignored/ waiting patiently, for some while now?    (http://freesmileyface.net/smiley/love/love-172.gif) (http://freesmileyface.net/free-love-smileys.html) 

Isn't it time to pay her a little attention?   :D

David D

Title: Re: Triple expansion engine valve arrangement
Post by: Bluechip on August 18, 2011, 05:15:25 AM

Stew


What's a 'POP CORN' engine ???

Dave BC

Title: Re: Triple expansion engine valve arrangement
Post by: sbwhart on August 18, 2011, 05:25:05 AM

Hi Dave

A popcorn engine is a little steam engine that they used in the US on carts to drive the drum that they roasted pop corn and salted peanuts in in the 1890.

the're are a few different types, ones a wobler another is a small horizontal.

If you google Creators popcorn engine or Dunbar popcorn engine you'll get lots of hits.

Stew

Title: Re: Triple expansion engine valve arrangement
Post by: Bluechip on August 18, 2011, 05:53:40 AM

Hi Stew

The only involvment I've had with pop-corn is some bagged-up stuff my mates daughter had to shove in the microwave .. which turned out to be edible to my amazement. ( Or very nearly!! )

Got some pics here for the Dunbar Engine .. and oven wotsit.

http://modelsteam.myfreeforum.org/viewtopic.php?t=32977&start=0

Very nice little-ish engine. Would make an attractive model.

Learn something every day ... thanks Stew ..

BC

Title: Re: Triple expansion engine valve arrangement
Post by: sbwhart on August 18, 2011, 08:16:47 AM

Thanks for the link Dave

Every engine seems to be different in some small way, I think they were for ever developing them, with this one its how they are supporting the valve rod with the curly up bit from the cylinder cover, I've seen them with nothing at all and with a column coming up from the base to give support. The plumbing around the governor is always different as well.

They all have flywheels with curved spokes that seems to be a common theme, got to work out how to fabricate one of those up, got a few ideas not sure how it will work out when I get round to making it the fly wheel is going to be the first bit if I can't get curvy spokes I may abandon the idea.

Stew

Title: Re: Triple expansion engine valve arrangement
Post by: AdeV on August 19, 2011, 05:44:37 AM

Didn't Bogs post an article about curved-spoke flywheels a while back?

I'll go a-hunting...

Edit to add:

I was wrong, it was Bernd, here: http://madmodder.net/index.php?topic=3392.0

The off-site link leads to a post with several pictures, but no real description, so I guess we'd all be interested in one of your most excellent descriptive how-tos, Stew (hint hint!)  :nrocks:

Title: Re: Triple expansion engine valve arrangement
Post by: doubleboost on August 19, 2011, 07:03:11 AM

If you make a woodern pattern i would cast you one in bronze :drool: :drool: :drool:

Title: Re: Triple expansion engine valve arrangement
Post by: sbwhart on August 19, 2011, 08:10:10 AM

Quote

If you make a woodern pattern i would cast you one in bronze

Quote

so I guess we'd all be interested in one of your most excellent descriptive how-tos, Stew (hint hint!)

If I fabricate one up could that be used as a patern that way we will all be happy.

I've had an offer of a cast flywheel by another member that may be the correct size.

But I'll fabricate one up any way just to see if it can be done.

Stew