Re: Stephenson Valve Gear

[William P. Davis]

Vance and all:
You can find both of the Bridgewaters' books; "more" is listed from several 
sources in the 21-25$US range on:

http://www.fetchbook.info/
I often do better than Amazon using this book search source (and it 
includes Amazon listings as well).

Will Davis
PS I wish that I was there, running trains !
At 10:01 AM 9/4/04 -0600, Vance Bass wrote:
Bob, good news and bad news: The good news is that the Levy book (the one 
I have) is
readily available used for under $10. The bad news is that the Bridgewater 
book is
readily available used for around $60, and the second volume ("More...") 
fetches about
$100.

If you had bought a hundred of the Bridgewater books ten years ago and put 
them in a
warehouse, you could afford one now!

-vance-
If you were here, we'd be running trains by now.

Re: Stephenson Valve Gear

[Dave Cole]

At 9:24 AM -0400 9/4/04, Walt Swartz wrote:
That might be a nice item for The Naples Depot to have on display.
fwiw, if memory serves, there is a full-size cut-away at the chicago 
museum of science  and industry that illustrates pistons and gear.

\dmc
--
^^^
Dave Cole
Gen'l Sup't:  Grand Teton & Everglades Steam Excursion Co.
  Pacifica, Calif. USA  
List Mom: sslivesteam, the list of small-scale live steamers
  
ATTEND THE NATIONAL SUMMER STEAMUP IN SACRAMENTO, JULY 21-24, 2005
For more information, visit the web site at 
^^^ 

Re: Stephenson Valve Gear

[Vance Bass]

Bob, good news and bad news: The good news is that the Levy book (the one I have) is 
readily available used for under $10. The bad news is that the Bridgewater book is 
readily available used for around $60, and the second volume ("More...") fetches about 
$100.

If you had bought a hundred of the Bridgewater books ten years ago and put them in a 
warehouse, you could afford one now!


-vance-

If you were here, we'd be running trains by now.

 

Re: Stephenson Valve Gear

[Cgnr]

I found the books available thru Amazon.com.  The title is:  Making 
Mechanical Marvels out of Wood by Raymond Levy; cost is $14.95.  Again, it's quite a 
delightful book, but I never did build any of the mechanisms.  This is a great 
book if you ever decide to do any Automata sculptures.  The other book that I 
was refering to is called:  Making Wooden Mechanical Models by Alan 
Bridgewater; $21.95.  It is out of print, but seems to be available used.  Both books 
come up on Amazon and you can look at the table of contents.
Bob Starr 

Re: Stephenson Valve Gear

[Walt Swartz]

Vance,
That might be a nice item for The Naples Depot to have on display. It would
be even better than a diagram because it would give a "hands-on" item for
the visitors. Keep me  in mind if you decide to go ahead with the project.
Something about 12" x 18" would be good for public display and use.
Keep your steam up!
Mr. Lunkenheimer's associate, Walt

 

Re: Stephenson Valve Gear

[Keith Taylor]

Vance,
While I am lucky to have an original cast iron valve gear demonstrator,
I do think that would be not only a nice display piece, but would go a
long way to helping folks understand just what is going on. It's a case,
again, of "a picture being worth a thousand words."
Keith Taylor
- Original Message - 
From: "Vance Bass" <[EMAIL PROTECTED]>
To: "Multiple recipients of sslivesteam" <[EMAIL PROTECTED]>
Sent: Friday, September 03, 2004 2:36 AM
Subject: Re: Stephenson Valve Gear


> I have been thinking lately that it would be cool to design one of
those hand-cranked
> valve gear models to laser-cut from wood. Is that something that would
interest anyone
> else?
>
> best regards,
>   -Vance-
>
> Vance Bass
> FH&PB Railroad Supply Co.
> 6933 Cherry Hills Loop NE
> Albuquerque, NM 87111 USA
> http://www.nmia.com/~vrbass/fhpb/
>
>

 

Re: Stephenson Valve Gear

[Vance Bass]

> There are two books published by Dover books that has designs of
> mechanisms made from wood that actually operate.  

Bob, I tried to find them online, too, without success. If you happen upon the titles, 
maybe we'll track one down one of these days.

Landon wrote:
> Any thoughts as to size, type of gear, price point?

None whatever. It's just one of those things on my mental list of cool things to do. 
Occasionally, I see one of those cast-iron demonstrators at a show or auction, and I 
think "why pay hundreds for that when you could make one yourself for pennies -- plus 
untold hours of design work?".  

But, given the visual interest and the relative simplicity of design, not to mention 
the 
pervasiveness in application, I would probably stick with Stephenson's.  

thanks,
  -vance-

 

Re: Stephenson Valve Gear

[Landon Solomon]

That would absolutely interest me.  I don't know that I could afford it 
anytime soon but that would be cool as... stuff... to have!

Any thoughts as to size, type of gear, price point?
Trot, the easily excited, fox...
|  /\_/\   TrotFox \ Always remember,
| ( o o ) AKA Landon Solomon\ "There is a
|  >\_/< [EMAIL PROTECTED] \ third alternative."
From: "Vance Bass" <[EMAIL PROTECTED]>
I have been thinking lately that it would be cool to design one of those 
hand-cranked
valve gear models to laser-cut from wood. Is that something that would 
interest anyone
else?

best regards,
  -Vance-
_
Express yourself instantly with MSN Messenger! Download today - it's FREE! 
hthttp://messenger.msn.click-url.com/go/onm00200471ave/direct/01/

Re: Stephenson Valve Gear

[Cgnr]

There are two books published by Dover books that has designs of mechanisms 
made from wood that actually operate.  I looked for it in their store, but 
could not find it readily.  I had the books and lost them in the fire; it did have 
the plans for making a hand cranked steam engine.  They are very nice book, 
as is all of Dover's stuff and well worth getting if you want to build 
something like that.
Bob Starr 

Re: Stephenson Valve Gear

[Vance Bass]

I have been thinking lately that it would be cool to design one of those hand-cranked 
valve gear models to laser-cut from wood. Is that something that would interest anyone 
else?

best regards,
  -Vance-

Vance Bass
FH&PB Railroad Supply Co.
6933 Cherry Hills Loop NE
Albuquerque, NM 87111 USA
http://www.nmia.com/~vrbass/fhpb/

 

Re: Stephenson Valve Gear

[Keith Taylor]

> Forget that, use Dockstader.  Do you know that when designing a
true
> Walschearts gear from scratch there are over 50 variables to be chosen
or
> set and most of them affect all the others.  It boggles the mind.

Harry,
Even with Dockstader, try to figure out what the heck you are watching
when working with baker valve gear! You have so many layers of
superimposed lines wiggling all over, it is easy to get confused. You
sit next to a nice model equipped with baker gear, and watch what the
bell cranks do, and it will all of a sudden start to make sense. Now, if
you are talking about designing a valve gear, and coming up with exact
dimesnions, then by all means Dockstader or the texts (I have a copy of
Auchinsloss, unfortunately, mine is the way more modern 1885 edition!)
are the way to go. But, to begin to understand just why a valve does
what it does, and not to worry about creating a design from scratch, I
still think taking some time to sit down with somebody that has been
through it before, and to watch the bits flailing around, it is a heck
of a lot easier than trying to figure out which dotted line goes to
which bell crank!
By the way, I personally think the easiest text to understand on
locomotive valve gears, is the Yoder & Wharren book reprinted by Camden
Miniature Steam Services in England. While it is a British Publisher,
the text is actually an old American text, and I believe at least one of
the authors worked for the Pennsylvania RR.
Keith

 

Re: Stephenson Valve Gear

[Harry Wade]

At 05:06 PM 9/1/04 -0400, you wrote:
>Now, my turn!
>If you can, the best way to begin to understand valve gears, is to sit
>along side a model that has the gear in question, and gently move the
>locomotive along the tracks, and while it slowly revolves, watch to see
>what the different links and lever do!

Keith,
  Knowing what the little sticks do is not the problem.  The problem
comes when I decide I need to consult, say, my Auchincloss ("Practical
Applications of Slide Valve and Link Motion", Van Nostrand, 1875) and do it
too late at night.  Then all those little lines and digits run together.

>was an ancient cut away model of a Stephenson's Link Motion,

For whatever reason, in rural Southern quasi-suburbia, we had one too.

>But, you can do the same by taking the diagrams in any of the books, make
mockups

Forget that, use Dockstader.  Do you know that when designing a true
Walschearts gear from scratch there are over 50 variables to be chosen or
set and most of them affect all the others.  It boggles the mind.

Regards,
Harry
 

Re: Stephenson Valve Gear

[Steve Shyvers]

Thanks for piping up, Keith. Your recommendation to make a moving model 
from a book diagram is great one! And not at all confusing. I will do it 
this coming weekend and will make it BIG so I can see it. The samples of 
valve gear simulation graphic software that I have seen are commendable 
efforts, but they're tough for me to really see. A set of cardboard 
valve profiles with different laps and leads would go a long way to 
helping improve my understanding.

I went back to one of the scholarly tomes tonight, and found reasonable 
definitions  for most items except there is no discussion of 
"advance".  Nor, of course, is there any discussion of simplified valve 
gears with no lap and its consequences for steam efficiency.

Thanks again to all. Enjoy your holiday in Italy, Bert. When you get 
back I'd like to ask you some questions about the small steam train I 
saw in a village south of Graz a number of years ago. I don't know if it 
was on display or operational, but it was parked next to a railway 
station in the village. My impression was that it ran, or used to run, 
to Ljubljana.

Steve
- Original Message - >
Steve wrote:
>I consulted a couple of ancient, dusty, and dog-earred tomes
 

both of them had good diagrams but lacked sufficient explanatory text
 

Then Harry wrote:
 

   I usually find the best old ones have such complex theories,
explanations, and diagrams as to be overwhelmingly tedious.  I suppose
   

you
 

could say that an "authority" could simply be someone who has been
   

able to
 

endure the tedium until they at last actually understand the subject.
   

Now, my turn!
If you can, the best way to begin to understand valve gears, is to sit
along side a model that has the gear in question, and gently move the
locomotive along the tracks, and while it slowly revolves, watch to see
what the different links and lever do! I was lucky, in that back when I
was in Middle School, hidden in a dark corner of a supply closet, was an
ancient cut away model of a Stephenson's Link Motion, as applied to
locomotives. There was one drive whell, with a hand crank on the axle.
As you cranked the model over, you could watch the valve move back and
forth on the valve seat, and as you linked up the reverser, you could
physically see how it shortened the stroke. Not everyone will have
access to such a model today, as I believe that schools no longer feel
it important to teach how anything works, and have removed most "shop"
classes from the choices available! But, you can do the same bytaking
the diagrams in any of the books, and cutting out cardboard bits and
pieces, suing a thumb tack at the pivot points to give you a hands on
way to explore valve gears.
I have come to the point where I now no longer believe that if I build
to a published plan, that the locomotive will automatically run! So, I
take the drawings, and make cardboard or masonite mock ups, at several
times the size of the model, and try the drawn dimensions. Then, you can
physically observe the valve events, and you wouldn't believe how many
times this method has pointed out errors in the published design! (I
won't mention the 3/4" scale Friend's Models Atlantic by name here) But,
it is easier to make changes to cardboard and hard board at an enlarged
scale, than to have to redesign the gear and make all new parts in
steel, when you find the locomotive will only run well in one direction!
(this is from the voise of experience here!) So, get a copy of any of
the valve gear books mentioned, and play around with cardboard mock ups,
it's amazing how quickly it comes to you! Looking at intersection dotted
lines on a drawings, is easily the worst way possible to learn how a
valve gear works. Particularly Baker gear, where one lever sits on top
of another, you begin to forget which line is which part!
Oh well, hope this hasn't confused you even more!
Keith
 

Re: Stephenson Valve Gear

[Keith Taylor]

- Original Message - >
Steve wrote:

 >I consulted a couple of ancient, dusty, and dog-earred tomes
> >both of them had good diagrams but lacked sufficient explanatory text
>
Then Harry wrote:
> I usually find the best old ones have such complex theories,
> explanations, and diagrams as to be overwhelmingly tedious.  I suppose
you
> could say that an "authority" could simply be someone who has been
able to
> endure the tedium until they at last actually understand the subject.
Now, my turn!
If you can, the best way to begin to understand valve gears, is to sit
along side a model that has the gear in question, and gently move the
locomotive along the tracks, and while it slowly revolves, watch to see
what the different links and lever do! I was lucky, in that back when I
was in Middle School, hidden in a dark corner of a supply closet, was an
ancient cut away model of a Stephenson's Link Motion, as applied to
locomotives. There was one drive whell, with a hand crank on the axle.
As you cranked the model over, you could watch the valve move back and
forth on the valve seat, and as you linked up the reverser, you could
physically see how it shortened the stroke. Not everyone will have
access to such a model today, as I believe that schools no longer feel
it important to teach how anything works, and have removed most "shop"
classes from the choices available! But, you can do the same bytaking
the diagrams in any of the books, and cutting out cardboard bits and
pieces, suing a thumb tack at the pivot points to give you a hands on
way to explore valve gears.
I have come to the point where I now no longer believe that if I build
to a published plan, that the locomotive will automatically run! So, I
take the drawings, and make cardboard or masonite mock ups, at several
times the size of the model, and try the drawn dimensions. Then, you can
physically observe the valve events, and you wouldn't believe how many
times this method has pointed out errors in the published design! (I
won't mention the 3/4" scale Friend's Models Atlantic by name here) But,
it is easier to make changes to cardboard and hard board at an enlarged
scale, than to have to redesign the gear and make all new parts in
steel, when you find the locomotive will only run well in one direction!
(this is from the voise of experience here!) So, get a copy of any of
the valve gear books mentioned, and play around with cardboard mock ups,
it's amazing how quickly it comes to you! Looking at intersection dotted
lines on a drawings, is easily the worst way possible to learn how a
valve gear works. Particularly Baker gear, where one lever sits on top
of another, you begin to forget which line is which part!
Oh well, hope this hasn't confused you even more!
Keith

 

Re: Stephenson Valve Gear

[Harry Wade]

At 08:46 PM 8/31/04 -0700, you wrote:
>I consulted a couple of ancient, dusty, and dog-earred tomes, Harry, 
>both of them had good diagrams but lacked sufficient explanatory text 

Steve,
I usually find the best old ones have such complex theories,
explanations, and diagrams as to be overwhelmingly tedious.  I suppose you
could say that an "authority" could simply be someone who has been able to
endure the tedium until they at last actually understand the subject.

Regards,
Harry
 

Re: Stephenson Valve Gear

[Steve Shyvers]

Mike, Keith, and Harry:
Thank you for the quick response. I got curious after comparing the 
Stephenson valve gear on my Graham single vertical to the C-16's valve gear.

I consulted a couple of ancient, dusty, and dog-earred tomes, Harry, 
both of them had good diagrams but lacked sufficient explanatory text 
for the tyro.

Steve

Re: Stephenson Valve Gear

[Landon Solomon]

From: Harry Wade <[EMAIL PROTECTED]>
<>
"Without laborious study of the ancient texts (which I ain't about to
do anytime soon) I can't say whether you are close or correct but IML&HO a
single eccentric does not a Stephenson's gear make.  I'd say that permutes
it into something else but what I don't know."
Regards,
Harry
Who knows if they are correct but I have seen the manufacturers refer to 
this arangement as "Simplified Stephenson's Gear".   Similar to how 
Roundhouse calls their favored gear "Simplified Walchearts Gear".

Trot, the popping-in, fox...
_
Don’t just search. Find. Check out the new MSN Search! 
http://search.msn.click-url.com/go/onm00200636ave/direct/01/

Re: Stephenson Valve Gear

[Harry Wade]

At 11:57 AM 8/31/04 -0400, you wrote:
>[snip a "true" Stephenson's Link Motion ALWAYS has two eccentrics,
>So, to make it short, if there is only one eccentric, it isn't Stephenson's
>[snip] So unless you make an exhaustive study of valve gears, some can >be
a bit difficult to identify.
>Sincerely Keith Taylor

Keith,
Hah!  Great minds (etc, etc) . . . I was just about to post this when
yours came in:
"Without laborious study of the ancient texts (which I ain't about to
do anytime soon) I can't say whether you are close or correct but IML&HO a
single eccentric does not a Stephenson's gear make.  I'd say that permutes
it into something else but what I don't know."

Regards,
Harry
 

Re: Stephenson Valve Gear

[Keith Taylor]

Steve,
I cannot say for sure about the C-16, but the reason that the Aster C7S
Mogul has only one eccentric, is because it isn't Stephenson's Link
motion! It is a modified form of Walchaerts gear, but without and anchor
and union link to impart the lap and lead functions to the valve,
sepeartely from the valve motion imparted by the return crank or
eccentric. An "true" Stephenson's Link Motion ALWAYS has two eccentrics,
or two return cranks. When the eccentric that provides the forward
motion is lined up with the end of the expansion link, the locomotive
moves forward with full valve travel. As you move the reverser towards
the center of the expansion link, the stroke of the valve is shortened,
until at the mid point, the valve doesn't uncover the ports at all.
Then, as you pass center, you begin to align the other end of the
expansion link with the reverse running eccentric, ever increasiong the
valve travel until you are lined up with the eccentric and the extreme
opposite end of the expansion link.
So, to make it short, if there is only one eccentric, it isn't
Stephenson's valve gear! Ther are many types of valve gear, that all
look similar, and it would probably help if you could find a copy of the
book, Model Locomotive Valve Gears by Martin Evans, or the one by Henry
Greenly, where there are good diagrams to show how each gear works.
I have a Bassett-Lowke No. 3 gauge steam locomotive (2-1/2" gauge) that
has a gear that also looks similar to Stephenson's Link Motion, but in
this case, the link doesn't vibrate with each revolution of the drivers,
and the link block slides up and down in the link with each revolution.
This a the Greenly's "corrected" motion, based on Joy valve gear. So,
unless you make an exhaustive study of valve gears, some can be a bit
difficult to identify.
Sincerely Keith Taylor   Jefferson Maine USA
- Original Message - 
From: "Steve Shyvers" <[EMAIL PROTECTED]>
To: "Multiple recipients of sslivesteam" <[EMAIL PROTECTED]>
Sent: Tuesday, August 31, 2004 10:05 AM
Subject: Stephenson Valve Gear


> At the National Summer Steamup Jeff Williams was kind enough to let me
> inspect the valve gear on his C-16. I had a question about why
prototype
> Stephenson valve gear had two eccentrics per cylinder that each drove
> one end of the expansion link. The C-16 has only one eccentric per
cylinder.
>
> After a little bit of study I believe that the answer to my question
is
> that the two separate eccentrics allow setting valve "advance" for
both
> forward and reverse. With only one eccentric per cylinder driving the
> expansion link it's possible to set valve advance for one direction
> only. The other direction would then have the opposite effect applied
to
> the valve timing.  Am I correct? Or close?
>
> Steve Shyvers
>
>
>
>

 

Re: Stephenson Valve Gear

[Mike Chaney]

Steve asked:-


> At the National Summer Steamup Jeff Williams was kind enough to let me
> inspect the valve gear on his C-16. I had a question about why prototype
> Stephenson valve gear had two eccentrics per cylinder that each drove
> one end of the expansion link. The C-16 has only one eccentric per cylinder.
>
> After a little bit of study I believe that the answer to my question is
> that the two separate eccentrics allow setting valve "advance" for both
> forward and reverse. With only one eccentric per cylinder driving the
> expansion link it's possible to set valve advance for one direction
> only. The other direction would then have the opposite effect applied to
> the valve timing.  Am I correct? Or close?

Absolutely correct.  The reason they get away with one eccentric is that the
valve cut-off is 100% (zero lap) and the eccentric does not need to be advanced.
This is an inefficient use of steam as it is not used expansively but makes for
a cheap and cheerful valve gear.  Most manufacturers of toy steam engines do it
this way.  It also allows for reversing to be achieved by using piston valves
and reversing steam and exhaust connections.

For a proper Stephenson's valve gear, take a look at a Catatonk logging engine,
a Graham steam motor or a DJB Mikado.

Mike Chaney