Baker Valve Gear

[NW Mailing List]

Bob - 

I’ve heard of this problem on the Southern.  Engineers who tended to hook their engines up too close to center complained that it went into reverse, which might have been explained by too much slop in the reverse linkage.  Engineers in the south seemed to be noted for this; when the CG got their 4-8-4s it was noted that a half-dozen or so notches either side of center on the reverse quadrant were blanked off so an engineer couldn’t latch the lever that close to center.

I don’t know that RF&P had that much Baker experience; if I recall correctly the only Baker engines they had were the 2-8-4s and the ex-N&W K-3s.  Correct me if I’m wrong; there could have been some early Baker enginers . . .

EdKing

From: NW Mailing List 
Sent: Tuesday, February 10, 2015 10:33 PM
To: nw-mailing-list at nwhs.org 
Subject: Baker Valve Gear

Ed -


I recall hearing from someone a while back that the RF&P and maybe Southern had problems with the Baker gear as it tended to screw up when set near center. Maybe it was a specific class or application, I don't know, but I heard that and it came from a solid source. That said, obviously N&W figured things out nicely and took full advantage of what Baker had to offer in its attributes vs. Walschert or others.

Does any of this ring any sort of bell to your knowledge area?

Thanks.

Bob Cohen


I don't think any development of Baker Valve Gear occurred in the sense that you?re thinking about.  The N&W got dissatisfied with Walschaerts gear early on with the E-1 Pacifics and M-1 4-8-0s, both of which (according to a long-time MP official who was a mentor of mine) that promoted rapid link block wear.  The M-2s were slightly better, as were the Z-1 2-6-6-2s.  You are referred to a treatise on valve gear in the ARROW entitled ?Monkey Motion?.

There was a predecessor of the Baker Valve Gear known as the Baker-Pilliod gear; it was applied as an experiment to class A 4-6-0 #89.  It was used on the first E-2 Pacifics of 1910.  The Baker-Pilliod gear supposedly gave quicker valve events for any given cutoff but was quite complicated.  A simplified version of this gear, known simply as the Baker Valve Gear (Abner D. Baker invented the gear, it was marketed by the Pilliod Company of Ohio) came out about 1911 and N&W adopted it as standard.  The Baker Valve Gear was patented and had to be obtained from the Pilliod Company.  Some railroads didn?t think it was worthwhile.  N&W obviously thought it was worth the cost.

As far as development was concerned, the Baker gear offered the advantage of providing a longer valve travel without introducing excessive angularities into the valve gear.  After 1911 N&W never used another valve gear.  The A of 1936 used Baker gear with a long valve travel.  The only refinement thereafter was the application of McGill ?Multirol? needle bearings for all the connections in the gear.

When the J came along, I don?t think there was any question of using any other valve gear, or using poppet valves.  The Baker valve gear driving the J?s big valves helped the engine to attain speeds of over 110 MPH (read Dave Stephenson?s treatises in the ARROW about the 610 tests on the PRR).  Such speeds required driving wheel RPM in excess of 535, almost unheard of elsewhere.  (Charles Faris designed the counterbalancing for the J; his figures were checked by Voyce C. Glaze whose workbooks are at the N&WHS Archives; the J might have been the most perfectly counterbalanced steam locomotive ever built, anywhere, anytime).

I hope this is helpful.

Ed King




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