Re: Eureka

I remember stopping on one trip at MP 337 to get water up in the boiler. We suffered with green wood for much of our Eureka Adventure. Getting started on the hill took some doing as Eureka would get stuck on center, have to back a foot or two, then try again. There was one spot where she would start every time. I recall if I looked down between the running board and the boiler, when the main rod oil cup was in a certain spot, she would start every time. I think Dan's heart went into his throat every time I ripped the throttle wide open to get her started.

Eureka proved the classic phenomenon of Stephenson Valve gear to pull harder if you can get a bit of a roll on things and hook it up higher. All the way up the hill we stomped along at about 8 mph, throttle wide open and the valve gear cut back to where she would maintain that pace. Any lower, she didn't make a significant increase in speed, but she sucked up noticeable more water and wood. A notch higher, and she just fell on her face. So, I found her happy spot. But as we went through the sag at Coxo, I got a roll on her, hooked up a couple more notches and swung around the curve. Out came the throttle and Eureka started for Cumbres at about a healthy, 12 mph. The grade soon took the wind out of her sails, and we started to slow, I dropped her down a notch (still one higher than before) and Eureka settled in at 11-12 mph hooked up higher than before and kept pouring it on all the way to the top. She was easier on the water and wood too.

The reason for this is when Stephenson valve gear is hooked up, it not only cuts the admission of the steam off to the cylinder earlier in the stroke, it also moves the timing of the admission ahead in the beginning stroke to ahead of the center. The technical term for this is "lead". This gives a bit more "punch" to the steam at the beginning of the stroke, not unlike advancing the ignition of a gasoline engine. Hooking up too high at too low a speed makes the engine struggle against itself.

I later saw this again in Texas with the Pretty little Texas & Pacific 316. At first she ran OK, she only hooked up about 2/3 of the way toward center, and it took a wide open throttle to climb every hill. She had a pretty healthy appetite for fuel and water too. After a bunch of fiddling, I got her to run about 4 notches higher and the difference was immediate. She had a lot more power hooked up high, where I would climb the hill eastbound from the Neches River with the throttle back against the tender and be lucky to keep 20 mph, she began to accelerate. I decided to see just what she had in her and let her run. When we topped 27mph with no end in sight, I finally had to give in and ease off the throttle. Our fuel consumption went from 1100 gals a day to 875 gals. We had been going through about 4000 gals of water each way and that dropped to around 3000. Amazing what a few shims in the right spot can do.