"Steam" container

The steam container is a top-level config.txt file entry used by Steam Enginespec assets.

Supported Tags

The Steam container supports the following tags. Each tag is show here with its default value.

steam
{
	boiler-volume 10.0
	burn-rate 0.5
	burn-rate-idle 0.01
	firebox-heating-surface-area 20
	firebox-efficiency 0.75
	firebox-thermal-conductivity 10
	firebox-plate-thickness 0.016
	fuel-energy 27912000
	fuel-specific-heat-capacity 1260
	initial-boiler-temperature 373
	max-coal-mass 1000
	ideal-coal-mass 500
	min-fire-temperature 500
	max-fire-temperature 1300
	minimum-volume 8000
	maximum-volume 9000
	fusible-plug-volume 7500
	boiler-heat-loss 2.0
	piston-angular-offsets 0.0174,1.5254,3.0333,4.5413
	piston-volume-min 0.0272
	piston-volume-max 0.1505
	piston-area 0.1734
	safety-valve-low-pressure 1653
	safety-valve-low-flow 0.05
	safety-valve-high-pressure 1684
	safety-valve-high-flow 0.1
	shovel-coal-mass 5.0
	water-injector-rate 3.0
	water-injector-rate2 3.0
	boiler-efficency-idle 0.75
	boiler-efficency 0.4
	boiler-efficency-min 0.25
	speed 15.0
	cutoff 0.4
	blower-effect 0.5
	blower-max-flow 2.5
	starting-coal 500
	starting-water 7500.0
	starting-boiler-steam 10.0
	steam-chest-volume 0.1233
	steam-chest-max-flow 25.0
	valve-lap-percent 0.05
	hand-brake-max-force 1000
	super-heating-constant 100
	tractive-effort-constant 0.8
	number-cylinders 2
	number-power-strokes 2
	legacy-piston-count 4
}

boiler-volume

Type: Decimal

Desc: Volume of the boiler, in cubic metres.

Note that in earlier versions of Trainz (pre TC3, trainz-build <2.8) this value was in litres, and newer versions of Trainz will multiply the value when it's read in from the config file.

burn-rate

Type: Decimal

Desc: The tested/'normal' rate at which the firebox burns coal, in kg/s (before being scaled down by drafting rate).

burn-rate-idle

Type: Decimal

Desc: The rate at which the firebox constantly/idly burns coal, in kg/s (before being scaled down by drafting rate).

firebox-heating-surface-area

Type: Decimal

Desc: Total surface area for heat transfer from the firebox to the boiler, in square metres. Larger areas result in more heat transfer, both cooling the fire and heating the water.

firebox-thermal-conductivity

Type: Decimal

Desc: Technically watts per metre kelvin, but real numbers are no good here - many factors mean a steam loco is far from an ideal heat conductor than the equations are based around. 10 seems to be a good number, found by experimentation. A higher number here will mean more heat transfer from the fire to the boiler - resulting in higher pressure but also less fire temperature. Lower numbers will result in more fire temperature, but less heating.

firebox-plate-thickness

Type: Decimal

Desc: Thickness of firebox plate in metres. 0.016 == 5/8" plate.

fuel-specific-heat-capacity

Type: Decimal

Desc: Joules per kilogram kelvin. Amount of energy (joules) needed to raise the temperature of 1 kg of the fuel substance by one degree kelvin.

fuel-energy

Type: Decimal

Desc: Joules per kilogram. Amount of energy (joules) that is released by burning 1 kg of the fuel.

firebox-efficiency

Type: Decimal

Desc: Firebox efficiency scalar, from 0.0 to 1.0. This directly scales the energy released from fuel burn, in order to approximate various heat losses from the firebox into the environment. Higher numbers mean more energy from fuel burn, lower numbers mean more energy is lost/wasted.

initial-boiler-temperature

Type: Decimal

Desc: Degrees kelvin. This value will determine whether the engine is 'ready to go' or needs 'warming up' prior to a run when first placed.

max-coal-mass

Type: Decimal

Desc: Maximum amount (kg) of fuel it's possible to cram in the firebox, before it starts falling out.

ideal-coal-mass

Type: Decimal

Desc: Ideal amount (kg) of fuel to have in the firebox for optimal burning. This value will appear as "100%" on the interface, and will burn the best.

min-fire-temperature

Type: Decimal

Desc: Degrees K. A higher value here makes the loco 'wake up' quicker, but too high a value will make it build pressure even when left idle.

max-fire-temperature

Type: Decimal

Desc: Degrees K. Lowering top end fire temperature will have the effect of limiting both top end boiler pressure and maximum water heating ability when working hard.

minimum-volume

Type: Decimal

Desc: Volume in Litres. This is the amount of water in the boiler that corresponds to the bottom of the sight glass - 0% on the interface. Defaults to 80% boiler-volume.

maximum-volume

Type: Decimal

Desc: Volume in Litres. This is the amount of water in the boiler that corresponds to the top of the sight glass - 100% on the interface. It should be above the 'minimum volume'. Defaults to 90% boiler-volume.

fusible-plug-volume

Type: Decimal

Desc: Volume in Litres. This is the amount of water in the boiler at which point the fusible plugs will kick in. It should be below the 'minimum volume'. Defaults to 75% boiler-volume.

boiler-heat-loss

Type: Decimal

Desc: factor used to cool boiler water over time. Bigger number == more cooling. Magic number (unknown units). Sample: 2.2

piston-angular-offsets

Type: Decimal Array

Desc: Values are specified in radians. Amount of wheel rotation required to rotate each piston to maximum travel from starting position. Will depend on how the valve gear has been animated in max. One value per piston.

piston-volume-min

Type: Decimal

Desc: clearance volume of a piston - i.e. the volume at minimum travel. This value greatly affects the level of front-end power available to a specific loco.

piston-volume-max

Type: Decimal

Desc: Total volume of a piston at maximum travel - i.e. the swept volume (stroke*area) plus the clearance volume.

piston-area

Type: Decimal

Desc: Surface area of the piston (metres squared).

safety-valve-low-pressure

Type: Decimal

Desc: Pressure (absolute, and in kPa) at which the low pressure safety valve will blow.

safety-valve-low-flow

Type: Decimal

Desc: Kilograms per second of steam that escape through the low pressure safety valve. Note: Too high a value will result in a 'sawtooth' boiler pressure, and repeated short hisses from the safety valve.

safety-valve-high-pressure

Type: Decimal

Desc: Pressure (absolute, and in kPa) at which the high pressure safety valve will blow.

safety-valve-high-flow

Type: Decimal

Desc: Kilograms per second of steam that escape through the high pressure safety valve. Remember that both valves will be open at this point.

shovel-coal-mass

Type: Decimal

Desc: How many kg of fuel does the fireman move each time he shovels?

water-injector-rate

Type: Decimal

Desc: litres of water moved into the boiler per second through the first injector when fully on.

water-injector-rate2

Type: Decimal

Desc: litres of water moved into the boiler per second through the second injector when fully on.

boiler-efficency-idle

Type: Decimal

Desc: Ratio (0.0 -> 1.0). Maximum efficiency of boiler - e.g. when loco idle.

boiler-efficency

Type: Decimal

Desc: Ratio (0.0 -> 1.0). Efficiency of boiler when working at test parameters.

boiler-efficency-min

Type: Decimal

Desc: Minimum boiler efficiency. Calculated efficiency will not fall below this value.

speed

Type: Decimal

Desc: Speed of test run on which test parameters are based.

cutoff

Type: Decimal

Desc: Ratio (0.0 -> 1.0). Position of cutoff control for test run.

blower-effect

Type: Decimal

Desc: Multiplier. Sets the effectiveness of the blower. Value is the draft effect of working the loco at the test parameters compared with running the blower at maximum boiler pressure but the loco otherwise idle.

blower-max-flow

Type: Decimal

Desc: Kilograms per second of steam used by blower at max boiler pressure and max setting.

starting-coal

Type: Decimal

Desc: Kilograms of coal to start with in the firebox. Ideal-coal-mass value will be used if this is not present.

starting-water

Type: Decimal

Desc: Volume of water (in Litres) to start with in the boiler. Will default to 85% boiler-volume (equivalent to halfway between 'max' and 'min' on the sight glass.)

starting-boiler-steam

Type: Decimal

Desc: Amount of steam to start with in the boiler. If this is too high, a false 'high pressure' will be reported at initial startup (but working the loco will reduce it). If it is too low, the boiler will boil water to build pressure, so using a low value (maybe even zero?) is suggested.

steam-chest-volume

Type: Decimal

Desc: Volume (metres cubed) of the steam chest. A good estimate if unknown is piston-volume-max * number of cylinders (source 5AT website).

steam-chest-max-flow

Type: Decimal

Desc: Max flow (kilograms per second) of steam from boiler to steam chest with regulator fully open.

valve-lap-percent

Type: Decimal

Desc: Ratio (0.0 -> 1.0)

hand-brake-max-force

Type: Decimal

Desc: Maximum force exerted by handbrake.

super-heating-constant

Type: Decimal

Desc: Degrees (kelvin) to increase temperature of steam between boiler and steam chest. High superheat results in more power at the front end.

tractive-effort-constant

Type: Decimal

Desc: Used to calculate theoretical performance along with cylinder dimensions for the AI to use. Defaults to 0.4 * number_of_cylinders.

number-cylinders

Type: Integer

Desc: Number of cylinders.

number-power-strokes

Type: Integer

Desc: Number of power strokes per revolution. Two is by far the most common number, but this can be other numbers in extreme cases.

legacy-piston-count

Type: Decimal

Desc: Used for loading old (TRS2006) saved sessions. An omission in the TRS2006 save format causes a loco with a different number of pistons not to load properly. The number of pistons often needs to be changed when updating old enginespecs, as previously engines had to have twice as many single acting pistons, rather than the correct number of double acting pistons as they do now. This value is to record the old number of pistons so that old sessions can still be loaded.

Example steam container

TBD