Interchangeable Valve Gear

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dnevil
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Interchangeable Valve Gear

Post by dnevil »

Back in the 1940's and before, it was common practice to scratch-build O gauge steam locomotives. Even though they were only steam outline and powered by an electric motor, they still required a full set of rods and valve gear to look realistic.

Rollin Lobaugh had an innovative idea of providing pre-made valve gear and side rod parts. Take a look at his ad below.

Could this concept be applied to our live steam hobby? Could a vendor provide standard Walschaert, Baker or Southern valve gear parts? Perhaps kits for upgrading from Stephenson (e.g. adding outside valve gear to an Allen Mogul)?
2021-12-12 19.08.11.jpg
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B&OBob
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Re: Interchangeable Valve Gear

Post by B&OBob »

The Piliod Company, of which Abner Baker was Vice President, was patent holder and marketinmg agent for the Baker Valve Gear. Originally invented for use on traction engines, Pilliod exploited the basic design for a limited variety of "bolt-on" products to accommodate a wide range of valve travel on locomotives with inside or outside admission.

Baker valve gear is comprised only levers connected through pin joints, so there is are no complex expansion links and close-fitting die blocks. Maintenance, when eventually necessary, requires only replacement of simple bushings and pins.

A considration in use of the Baker valve gear is the width of its frame and what effect that might have due to loading gauge restrictions or, perhaps in the case of narow gauge prototypes, appearance. Loading gauge limitatiions were one reason the Baker gear was not adaptable to European railways.

Design of Baker valve gear has been the topic of numerous articles in the live steam press. It was described in detail by LBSC in 1928 and numerous British and domestic articles since then, including The Model Railroader, no less, which published an informative "stop-action" explanation in March 1938! However, the definitive guide to the Baker valve gear is Piliod's own 65-page booklet published in January, 1931.

Whether a vendor would want to devote time and development costs to a bolt-on replacement V.G. would be a valid question, as would also be the skill level required of the locomotive's owner in making the modification. The Baker gear would certainly be a good candidate for the modification in any event.

All good food for thought, however.

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Berkman
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Re: Interchangeable Valve Gear

Post by Berkman »

I thought allen models did have drawings for Walscheart, baker, southern VG adoptions on their locomotives. All of these valve gears have been applied to their locomotives at one time or another. I've always thought putting SOU vg on an Allen 2-8-0 would be really neat.

I've also seen baker VG fabricated and made to fit a LE pacific. Someone I remember reading was planning to use Roger goldman's short frame baker on a heavy mikado.
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Bill Shields
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Re: Interchangeable Valve Gear

Post by Bill Shields »

Southern VG for models as 'interchangeable would be a very tough go..

Having been through it recently, modelling a copy of a loco B&O Bob's father built -> Southern is a real learning experience, especially when the vertical position of the springs / main drive axle with respect to the center line of the valves makes a significant difference to the running valve position.

In the end -> to get the valve events correct -> I ended up doing what Bob's father did - and locked the suspension for the main driver so that it would not move.
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Re: Interchangeable Valve Gear

Post by Berkman »

SOU rr of course had a lot of locomotives with SOU VG, I have heard of valve events changing in curves and such, but also I don't think TVRM/NS ever had issues with SOU 630 or 722 over the years on excursions.
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Bill Shields
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Re: Interchangeable Valve Gear

Post by Bill Shields »

It is a good gear -> and on a full size loco the suspension position does not move that much except on high speed curves

On our smaller locos it is an entirely different kettle of fish

Once you actually get into building designing and installing a SOU VG the condition becomes blatantly obvious.
Too many things going on to bother listing them.
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