Guys
Can anyone offer suggestions on where I can find some Walschaerts Valve Gear drawings? Specifically the Walschaerts arrangement like on the Soo Line 440 or the Sp&s 2-8-2. If anyone could elaborate why this different setup from the “standard” arrangement on other locomotives.

-clinch670

I have drawings of all Maine Central's Baker valve gear. I realize Baker isn't Walshaerts, but I'll throw it out there.

Hi Clinch670,
I recommend the International Correspondence School books/booklets on Walschaerts valve gear. ICS published a two part discussion on Walschearts valve gear. There is also a title on the valves themselves, and that book is integral to the discussion of the valve gear as a whole. To the best of my knowledge (which may be wrong), the titles were published and can be found in all three of the typical ICS forms:

--Brown stapled paper booklets, with one or two booklets ("volumes") per subject.
--Hardbound volume with red and green binding titled "Locomotive Valves and Valve Gear," bearing the imprint of the "International Library of Technology"
--Hardbound books with a dark blue binding bearing the imprint of the "International Textbook Company."

I own a copy of the red and green International Library of Technology book. I recommend it, as it combines in one volume the ICS booklets on the following topics:
--Slide and piston valves
--Walschaerts valve gear
--Stephenson
--Baker
--Young
--Southern

I also own a few books by other authors, such as Charles McShane, on valve gears. However, I recommend the ICS books, as the illustrations are the best and clearest.

As to your second question, I wasn't able to find many pictures of SP&S 2-8-2's online, but I did find some good pictures of Soo Line 440. You might find the diagram located halfway down the linked page helpful for the following discussion:
https://en.wikipedia.org/wiki/Walschaerts_valve_gear

Soo Line 440 has indirect Walschaert's valve gear. On most locomotives, with direct valve gear, the radius rod (no. 8 in the diagram) is moved into the lower portion of the reversing link (no. 7) for the locomotive to move in forward gear. In the wikipedia diagram, they call the reversing link (no. 7) the "expansion link," which I'm guessing is the British practice. The radius rod is raised to the upper portion of the reversing link for reverse gear.

This is called direct valve gear because the piston moves forward when the eccentric crank pushes the eccentric rod forward, and back when the eccentric crank pulls back. Thus the two motions are directly related. Nowadays I think we would call it "comoving" or something, but 100 years ago they decided to call it "direct motion."

On a locomotive with indirect valve motion, the reverse is true. The radius rod is raised to the upper portion of the reversing link for forward gear, and placed in the lower part of the reversing link for reverse gear.

Whether a locomotive has direct or indirect motion is determined by the orientation of the eccentric crank. For a locomotive with inside admission piston valves, the locomotive will have direct valve gear if the eccentric crank trails the crankpin when the wheels are spinning forwards. The locomotive will have indirect valve gear if the eccentric crank leads the wheels while the wheels are spinning forwards. The conditions are reversed for direct/indirect motion on locomotives with outside admission valves (like slide valves or the ever-so-rare outside admission piston valve).

Direct valve gear was favored for two reasons:
--Having a locomotive running with the radius rod in the top of the reversing link results in about twice the force being applied to the reversing link bearing (called the trunion bearing) compared to that when the radius rod is in the bottom of the reversing link. The increased force on the trunion bearing results in greater wear, so it's better to have the locomotive run forwards with the radius rod in the lower portion of the reversing link, because road locomotives generally spend more time running forwards than backwards
--More importantly, if one of the pins or linkages responsible for raising and lowering the radius rod were to break, gravity would pull the radius rod down. On a locomotive with direct valve gear this would make the locomotive go into full forward gear. On a locomotive with indirect valve gear, this would make the locomotive go into full backwards gear. Road locomotives tend to go much faster forwards than backwards, and for much more time, so it's better to have a locomotive fail forwards than backwards. Having an indirect-motion locomotive suffer a broken lifting link at speed might be catastrophic.

These two conditions don't really affect switch engines all that much, because they spend equal amounts of time going backwards and forwards and don't usually go all that fast.

I don't know why railroads bothered with indirect motion on road engines at all. I have a hunch that it may have had something to do with the intricacies of the power reverse gear that ALCO installed during the 1910s. Perhaps somebody else can elaborate more. I would mention also that SOO 1003 has indirect valve gear, and is the largest locomotive I know of to have it.

The ICS reference books mentioned can be found herehttp://www.icsarchive.org/

The blue books for railroads are typically in the 500 series and the downloadable editions can be found after clicking on the icon that looks like a funky library.
http://www.icsarchive.org/icsarchive-org/bb/
Mike Tillger

How difficult would it be to have indirect valve gear converted to direct? Has it been done?

if you aren't already familiar with the valve gear simulations created by the late Charlie Dockstader, you should take a look at them. Indirect Walschaert isn't supported, but inside and outside admission Walschaert are, as well as a number of other locomotive and other steam engine valve gears. Each includes a computer simulation of the valve gear and allows for modifications to dimensions of the components so you can see what the affect of changes. http://www.billp.org/Dockstader/ValveGear.html

It's been done accidently several times in the preservation era, by people installing the main driver wheel set in backwards (spun left to right), since the eccentric cranks are set mirror image one side to the other, or by people replacing the main crankpin(s) who then set the eccentric crank(s) to the wrong side of the axis. The end result that the freshly completed engine is taken back apart to return the pieces to where they belong, so it doesn't run in reverse when you put the Johnson bar in forward.

To convert an engine on purpose, the first step is to do the above (except on purpose), and then change the orientation of the reverse shaft or change the connection from the Johnson bar to the reach rod so that putting the Johnson bar in full forward results in the radius rod going down instead of up.

As a long time Soo Line fan, this is interesting to me. The Soo liked Walschaerts valve gear, equipping just about everything on the road with it during the teens and twenties as they rebuilt and superheated engines built as compounds. About the only thing that survived with Stephenson valve gear were the Brooks built engines that had piston valves inboard of the frames... too much trouble, I guess. Anyway, published lore is that Soo engines were always noted for their square exhaust, and supposedly a Soo shopman was granted a patent for an improvement to Walschaerts valve gear, the "Ripton link".

Can anyone add discussion as to why the Soo should favor indirect motion?

Articulateds often had one engine set up with indirect Walschaerts to act as a couterbalance to the weight of the other engine's radius rods.

Other than that, I can't think of any good reasons, though they were out there, I spot them in old photos fairly often. I believe that Magma Arizona #5 (the 2-8-0) has indirect Walschaerts.

You are right, Kelly. Magma Arizona #5 was the locomotive I was thinking of. I'm quite fond of her and if the opportunity presented itself, I'd make things right with her...

I didn't recognize the name, but going from 6-ET's description, the Alaska Railroad 550 class and over 2,100 other USATC Consolidations have indirect Walschaert's valve gear. Here is a nice photo cropped from a BLW builder's photo of ARR 555. We have drawings of most, if not all of the individual parts of the valve gear. Unfortunately, I haven't been unsuccessful in finding a valve gear assembly drawing.

The Dockstader valve gear software gives quite a bit of flexibility. It's been at least 10 years since I used it. There is a chance you could modify it, possibly with some negative values, to simulate the indirect valve gear. If you want to give it a try, I can give you all the dimensions for the USATC Consolidations.

I don't think that builders supplied them. At least I have never seen one in builders blueprint packs, just drawings of the individual valve gear parts.

Kelly, that tends to verify what I had suspected. Neither the BLW nor Lima drawing indexes for the locomotive list a valve gear assembly drawing.

Southern Ps-4 Walschaert assembly from a Southern drawing.
http://southernmodeler.info/Ps4/SR_DWG_ ... e_Gear.pdf

Guys thank you so much for your response. I’ve really learned a lot reading these posts. I’m currently working on designing the valve gear for a Clinchfield 2-8-2 with indirect valve gear.

-clinch670