I am building a live steam loco. It’s a kit from Roundhouse Engineering, and it’s relatively straightforward to build. Last weekend I lit the burner for the first time, raised steam and tested to see if it would run.
The black vertical tank at the back is the gas tank, and contains gas – basically the same stuff as Camping Gaz. There is a wheel to control how much gas flows out of the tank into the burner, which runs in a tube in the middle of the boiler.
The boiler (the large horizontal copper tube) is mostly filled with water, and has another smaller tube within it containing the burner (so that the burner doesn’t get wet). The burner heats up the boiler, heating up the water, producing steam. The steam gathers at the top of the boiler, building up pressure.
The regulator controls how much of that steam is sent to the pistons (at the front, via an internal pipe that you can’t see). The reversing lever moves the mechanisms at the side – “valve gear” – to determine if the loco goes forwards or backwards.
The safety valve correctly operates when there is too much pressure in the boiler, preventing the boiler from exploding. In the second run, the loco moves. The motion is jerky because the valve gear it hasn’t been properly “tuned”, and the loco hasn’t been run in yet. Running in requires running the loco on the track, or raised up on blocks, for several hours.