Thanks Winn - I found a drawing of one someone else built. While I can't comeup with my own I can (use to) be able to follow someone else's plan. 8^)
Semper - interesting way to control it. Kind of like riding the breaks to control a car.
Not really "riding the brakes"...
"Real" valve gear on a steam engine changes the flow of steam in the cylinders based on the position of the wheels and the position of the reverser. It can be adjusted by the lever in the cab to vary how long steam is admitted to the cylinder (called "cutoff") and thus use the expansive force of the steam to move the piston instead of the pressure in the boiler. Moving the lever closer to center (called "notching up"), shortens the time that steam is admitted and thus you maintain speed, but use less steam, so less water and thus less fuel... it is often called the "Company notch" because of the "Savings" it provides.
Ruby's valve gear has a fixed admission time and does not change when the lever in the cab is moved. Instead, that lever in the cab just reverses the flow of steam in the Valve Chest, changing it from "inside admission" to "outside admission" (and vice versa) to change the direction of wheel rotation. The lever controls a 3rd valve hidden between the frames to swap which way steam is flowing to the Valve Chest. Moving the lever closer to center just pinches off the flow of steam, just like what closing the throttle valve does, and does not change the amount of time that steam is admitted to the cylinders. It is more difficult to adjust it in fine increments. A small amount of movement of the lever results is a great amount of change in the steam flow... Unlike moving the throttle where you have a finer control of the amount of steam that is allowed to flow; a small amount of movement makes a small change in the amount of steam that is flowing. But with R/C control, your hand/eye coordination can detect speed changes and make quick small adjustments easier to do.
