Realistic Steamer Overhaul

Realistic Steamer Overhaul

Quick Start

• []Open the damper by pulling it up.

  []Add 1 or 2 shovelfuls of coal to the firebox and light the fire.

  []Set the reverser to full forward or back.

  []Slowly open the regulator until the locomotive starts moving.

  []At about 10 kph, reduce reverser to 1/2 and open the regulator.

  []At about 20 kph, reduce reverser to 1/4 and open the regulator to full.

  []You may now control acceleration by adjusting the reserver.

  Tips

  • []Adjustments to the regulator, reverser, and blower will have a large effect on firebox temperature and steam generation rate. Reverser settings below 1/4 will generally not generate enough steam to maintain pressure.

    []Do not add too much coal to the firebox! If the smoke from the chimney is dark black, turn on the blower until the temperature gauge stops rising.

    []If blower is fully opened and smoke is still black, dump coal from the firebox by holding opening the Fire Out valve.

    []Opening the injector too far will rapidly reduce steam pressure. It is best to refill the boiler when coasting after a hard climb, to avoid losing steam pressure through the safety valves.

    []When coasting with the injector closed, closing the damper by pushing it down will reduce coal consumption and steam generation, preventing loss of steam through the safety valves. Don't forget to open the damper again before opening the regulator!

    Background

    What is cutoff?

    Cutoff is the point at which the intake valve closes, preventing more steam from traveling from boiler into the cylinder. Before the cutoff point, the steam in the cylinder is nearly full boiler pressure. After the cutoff point, no further steam enters the cylinder, and the pressure drops as the piston moves. However, the steam already in the cylinder continues to push against the piston, giving "free" energy. This is called "expansive working," and is key to efficient operation of a steam engine.

    If we lengthen the cutoff, the valve closes later, more steam travels from the boiler to the cylinder, and cylinder pressure remains high for a longer time.

    (Click here for an interactive version of this graph)

    The work done by the steam on the piston is the area under the curve. Let's see how the work done, and consequently the power output of the steam engine, changes with the length of the cutoff:

    The lower line shows how much steam is admitted to the cylinder, and the upper shows the total work done by that steam. The distance between the two lines is the amount of "free" energy obtained through expansive working. If we normalize this graph by the amoun