Lois,
That motion doesn’t look right to me.
I am not knowledgeable of the specifics. I posted it only as an example. If I had a close view of the valve gear of the J in operation that might have allowed me a better comparison.
I’m sorry to have to tell you that Charlie died near the end of 2011.
Does the Bitter Creek Western archive site not work?
I also recommend Don Ashton’s Web site which also has links to Hall’s and Wallace’s programs.
These were all ‘live’ the last time I downloaded files to a Windows system, and they should still be good. Let me know if not.
I certainly make no claim to expertise in the matter of any valve gear, but I wonder if the difference between gear used with inside admission valves and the gear used with outside admission valves is a contributing factor to the difference in understanding how Baker valve gear works. Locomotive Up To Date shows that there is a difference between the two–though it shows a slide valve with the outside admission and a piston valve with the inside admission. “The Baker valve gear is direct in the forward motion and indirect in the back motion for inside admission, and the opposite for outside admission.” (p.295).
Overmod, I really thank you a lot. I was able to download the Pillard book and save it.
Overmod,
Thank you. The Bitter Creek site worked. I had not seen that one in my search.
The same is true for Walschaert valve gear.Go here and scroll down to pg.31 to read about direct and indirect movement in Pt.1 of the Walschaert section and pg.44 in the Baker section:
http://www.icsarchive.org/icsarchive-org/bb/ics_bb_504d_section_0000_walschaert_and_baker_valve_gears_1940.pdf
The same isn’t true for Walschaerts-- if you have 1922-1930 Cycs you can probably find pics of Walschaerts engines with inside admission that are indirect in forward gear. (Think it was ALCo that liked that.)
Timz,
If you went to the site provided, you did not read down far enough. Try page 32, item number 49 “Inside Admission Valve - Indirect Motion”.
So all agreed inside-admission Walschaerts engines were known to be indirect in forward gear?
No, that is not agreeable. Did you stop at item #49 and not read down to item #51 where it can also be direct?
Whatever it says, the Cycs have pics of 4-6-2s and a couple of 4-8-2s with inside-admission valves and Walschaerts that’s indirect in forward gear (so the eccentric crank is 90 deg ahead of the main crank).
I would be interested in seeing them. Can you post a picture or two?
So, what you are referring to is like what is shown in Fig. 9 between pages 14 & 15?
That is odd-- why does the book show indirect-in-forward-gear Walschaerts in Figure 9 is if it were the usual form, and only later mention the disadvantage of that form? But yes, that’s what I mean. In Rwy Age (in the 1920s?) someone said indirect-in-forward-gear Walschaerts gave better valve events than the usual direct gear-- would be interesting to see details. Could be true for all I know, but apparently that didn’t make up for the disadvantages.
I don’t have a scanner-- do you have those Train Shed Cyclopedia reprints of the 1922 and 1930 Cycs? (Don’t recall if Gregg did any reprints of the 1927.)
As a question of interest, the picture of DL&W American 938 on page 150 of the book Guide to North American Steam Locomotives (Kalmbach, 1999 printing) is of interest. This locomotive has Baker valve gear, something that is almost nonexistent on locomotives of this wheel arrangement. In the text, 10 of these locomotives were rebuilt in the 1920s, receiving new cylinders as well as the Baker valve gear. lois
No, I don’t have any of them. Never even been able to put my hands on one in order to look through to see if it was something that I would want.
On another note, if I am not very much mistaken, I think that N&W’s Z1 with slide valve LP cylinders and piston valve HP cylinders had different styles of Baker gear on each engine.
When the D&LW 4-4-0’s were rebuilt with Piston valves, where they superheated?
Is the reason slide valves don’t work with superheat lubrication?
Is it possible that one pair of cylinders had the original, Baker-Pilliod, gear, which was patented in 1903, but not put into use until 1908 (on a Toledo, St. Louis & Western locomotive), and the other pair had the gear that was patented in 1910?
There is no description of the Baker-Pilliod gear in Locomotive Up To Date.
On the same youtube page is this animation of the Baker valve gear which I like:
https://www.youtube.com/watch?v=GwzUCBMv4tA
Years ago when reading about the Baker gear, I had a hard time visualizing how it worked until I made cardboard cutouts of the parts using eyelets for pivots. For me the hard part was remembering which pivot points were stationary, which were stationary only for a particular valve setting, and which ones moved while running. It works!
[quote user=“nobullchitbids”]
What follows in others replies is a pretty thorough discussion. Little left to add, but so far no one has mentioned:
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Unlike diesels, steam locomotives usually were designed for the specific on-site task at hand. What gear was best for one was not necessarily best for others. All had to address the basic problem, which was to set the valves in the cylinder to regulate the cutoff of the steam.
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No one so far has mentioned the effect that superheating had on the problem. I’ve always been told that Stephenson only could be used with slide valves, which could not be used once superheating became the standard practice. This explains why Walschaerts took over at the turn of the last century even though it was invented half a century earlier.
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Why a road preferred one to another depended on several factors. Union Pacific, with its long runs typical of transcontinental bridge routes, liked Walschaerts because it was easy to maintain and easy to teach. And, as UP accumulated more engines, there also was the benefit for having to store fewer kinds of replacement parts. Remember: It was maintenance, not performance which killed the steam locomotive. There were no diesels at the time which could outperform an NKP S-3 or a Fetters 4-8-4.
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U.P. did experiment with the clever Young gear, which used the motion of the opposite side of the locomotive to set the timing and valve travel. This was sold by the companies as a maintenance improvement; but, in the end, U.P. changed its Young engines (by then mostly 4-8-2s and 2-10-2s) to Walschaerts, again because of the parts-inventory problem and to effect standardization.
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Of course, U.P. also is famous for use of the Gresley gear, which is needed for three-cylinder engines like the 4-12-2s. UP experimented with substituting a double-Walschaerts on the engineman’s side (the "bal