Hi. I'm wondering if someone could tell me if the eccentric crank for the Walscheart valve gear mechanism is fastened to the drive wheel at a standard angle to say the diameter through the connecting point or were different angles tried. It appears to me to be at about a 45 degree angle (or 135 degree from the other side of the vertex). Thanks for any input.
Well it was adjustable - unlike our models!! For example, when the engine was set to go forward, it leaned forward, when the engineer wanted to back up, he would change valve gear to be leaning backwards. This could be done by a big wheel and screw in the cab (usually this was done in the UK more than here) or by the reversing lever. It was all controlled by the engineer. Also there were subleties on the exact angle to allow the right amount of steam into the cylinders to use the steam the most efficiently.
I'm sure there was a maximum angle it could go to one way or the other, but not sure what it was....
If you meant what you said, then the poster above misread your post.
The angle formed by the two lines--
Center of axle to main pin
Center of axle to back end of eccentric rod (i.e. the outer end of the eccentric crank)
will usually be close to 90 degrees. As I recall it would be exactly 90 degrees if the link foot were level with the axle (at the midpoint of its swing), which usually isn't the case.
The exception is those few engines that are not set for constant lead.
Also, if you don't mind the correction, it is Walschearts , with the s. It is not the possessive form with an apostrophe missing, and it is not Walscheart. The gentleman's name was actually Walschearts.
I was surprised, too.
Here is a web page with animation for you to view;
http://home.new.rr.com/trumpetb/loco/
Nothing is more fairly distributed than common sense: no one thinks he needs more of it than he already has.
TomDiehl wrote:The Eccentric Crank is attached rigidly to the main driver crank pin at an angle of 30 degrees to the right of center
Or thereabouts. The angle will vary somewhat from engine to engine.
And of course some of them were left of center.
selector wrote: Also, if you don't mind the correction, it is Walschearts , with the s.
Or maybe Walschaerts?
Also, whether the eccentric crank leans left or right doesn't determine whether the engine has inside or outside admission. (Or vice versa.)
It's Walschaert.
To quote from that nice link Wallyworld provided:
By the way, Walschaert gear is correct; Walschaerts gear is not (unless it is used in the possessive case, with an apostrophe, eg: "Walschaerts' design"). The inventor's name was (Egide) Walschaerts (pronunciation: ay-gee-day val-sherts), but the design was patented under the name Walschaert for political reasons. Ref: Publications Style Manual, Pennsylvania Railroad Technical and Historical Society.
SW Chief wrote: It's Walschaert. To quote from that nice link Wallyworld provided: By the way, Walschaert gear is correct; Walschaerts gear is not (unless it is used in the possessive case, with an apostrophe, eg: "Walschaerts' design"). The inventor's name was (Egide) Walschaerts (pronunciation: ay-gee-day val-sherts), but the design was patented under the name Walschaert for political reasons. Ref: Publications Style Manual, Pennsylvania Railroad Technical and Historical Society.
Okay, let's call it a draw.
http://www.roundhouse-eng.com/ss02.htm
selector wrote: SW Chief wrote: It's Walschaert. To quote from that nice link Wallyworld provided: By the way, Walschaert gear is correct; Walschaerts gear is not (unless it is used in the possessive case, with an apostrophe, eg: "Walschaerts' design"). The inventor's name was (Egide) Walschaerts (pronunciation: ay-gee-day val-sherts), but the design was patented under the name Walschaert for political reasons. Ref: Publications Style Manual, Pennsylvania Railroad Technical and Historical Society.Okay, let's call it a draw.http://www.roundhouse-eng.com/ss02.htm
Then again, let's don't.
.
Interesting thought ..there are still folks who must design and build valve gear for steam locomotives albeit on a smaller scale...downloadable design programs..it never occurred to me how obvious there would still be a need to do this...
http://www.tcsn.net/charlied/
timz wrote: Also, whether the eccentric crank leans left or right doesn't determine whether the engine has inside or outside admission. (Or vice versa.)
Indirect Walschaert valve gear has the eccentric cranks set in the opposite position from normal -i.e., for outside admission, the eccentric crank will will follow the main crankpin; for inside admission, the eccentric crank will lead the main crankpin. Indirect gear was common on pre-power reverse locos, as "hooking up" the loco in forward motion, the mass of metal link blocks, linkage, etc. was lowered into the desired position, a much easier task than raising it. This info was gleaned from an article by E.W.King Jr., in the May 1984 issue of Trains magazine, which offered insights into all of the major variations of valve gear.
Wayne
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