Throttle valve

Stokes Throttle Valve
Richard Stokes sent the following letter to the editors of The North American Live Steamer, and was printed in the March 1956 edition.

I agree with E.R. Hathaway Jr., in his letter to your magazine, who contends that more articles should be written for the beginner. I for one, and I believe all of us, faced a bewildering and almost impossible beginning. Fortunately for me, I live in an area where old time builders are plentiful, but Heaven help the Live Steam beginner who lives apart from hsi fellow builders, All of us should add our experiences gained into this new North American Live Steamers magazine to encourage the beginner. He, too, likes the smell of burning coal, steam, and hot valve oil, as much as we do. It takes a long time and a lot of effort and experimenting to get 100 pounds plus of steel, iron, copper and brass to come alive so let's make it easier for him. I, for one, will be happy to contribute what little I have gained from building an engine.

So here is an idea that has been proven. A throttle that fits into the small smoke box. On my 10 wheeler it has given excellent results with never a spinning driver. Easy, slow starts and swell for switch yard work.

Richard J. Stokes

5155 Queen St.

Riverside, California



Ball Valves
Steven Hughes posted the following on Facebook, 21 May 2018:


 * The valve is a 1/2 NPT stainless steel ball valve from Duda Energy LLC (p/n 3PCBV2-F050). They also have smaller valves. The pressure & temp specs for this valve are excellent for steam. It's very reasonably priced at $12.25. James Davenport plumbed it into the smokebox & I set limits for the throttle opening & closing using axle collars set screwed onto the 1/4 rod running from the throttle control. It works very smoothly, with a good control gradient.



Screw Valve
From Chaski.org:


 * I don't know if this will work for you or not, but a screw down type works well, at least for me. The throttle valve rod comes through the back head terminating in a handle that can be turned to open it. No leaks with this type either. (Just remember to open the throttle at the end of the day).

Poppet-Valve
Ken Parkinson describes a design for a balanced poppet-valve throttle for a 1 inch scale locomotive. He claims it works well in the smokebox, steam dome, or superheater header. The design can be found in Live Steam Magazine, December 1977, page 49.