Mark's probably the guy that clued us in on using the drifting throttle to pull a train. Russ and I developed a system of using the drifting throttle to fine tune things and pull the train out of tough spots when running on flat parts of the railroad, as well and pulling the train out of the sags between Osier and Big Horn going east.
I developed a system of dialing in the throttle to the magic spot when running east just beyond Los Pinos where the grade levels out. According to the profile the railroad is virtually flat from around MP 325 east of Los Pinos to the other side of Rock Tunnel. It was possible to get the throttle set so things would roll along right at about 13 mph, which was the speed needed to maintain the schedule. All that was fine until you came to places where you to needed to do something. The first spot was the curve around Long Creek. I'd put a set under the train as I approached the curve, releasing it as the engine nosed into the corner. This kept the slack stretched, as when the engine would hit the curve, it would bind up and slow, the train behind rolling on the straight track would then run into the engine. Setting the air avoided that. As we rolled thru the curve, and the train began to bind up I'd open the drifting throttle. This would add just enough power to overcome the curve friction and keep us rolling at speed. Cascade Creek was another. Set the air to slow the train, to the required 8mph. Kick the air off, shuffle across the bridge, open the drifting throttle to get you back to speed on the other side.
Beyond Rock Tunnel the grade stair steps down with lots of flat spots where you have to pull the train, and if you planned far enough in advance, the drifting throttle was the perfect thing to pull the train through these spots.
As far as damaging the superheater units., opening the drifting throttle would put some steam into the units as it would feed back through the branch pipes and superheater header to the units as they are all connected together. The steam wouldn't flow anywhere as eventually the steam would run into the dry pipe and hit the backside of the closed throttle. But having a little steam in there was better than the traditional Rio Grand method of running down hill with the throttle closed, valve gear in the corner, and the relief valves sucking air into the cylinders, leaving the elements empty of steam with the ends exposed to the fire. But, that practice that we all learned is for another discussion.
