Help:Steam

Revision as of 15:59, 1 July 2014

Controlling a steam engine is quite different from a diesel or electric engine. Rather than throttle "notch" settings, the regulator and reverser are combined as the power control and balancing these and maintaining steam is central to steam locomotive operation.

Steam HUD

Steam HUD

In terms of the fields for monitoring Train Brake status the Steam HUD Panel is identical to the Diesel/Electric HUD Panel. Throttle and Reverser fields are replaced by the Regulator and Cutoff. In addition there are Boiler, Water, Steam Chest and Coal and fields which are used to monitor your current steam generation capacity.

Boiler

The Boiler field measures the current steam pressure in the boiler. The steam pressure in the boiler is dependent on a number of factors and maintaining a head of steam is one of the challenges in running a steam locomotive. When the nominal boiler pressure is exceeded, Safety Valves lift to vent excess pressure to the atmosphere. A good crew will avoid this waste of steam and fuel by striking a good balance between the temperature of the fire, the pressure in the boiler, and the conditions of the road ahead.

When approaching a heavy ascent for example, a hot fire is required to maintain adequate steam pressure. Conversely when approaching an easy section with a hot fire, the rate of pressure increase in the boiler can be eased to prevent lifting safety valves by adding more water to the boiler, or indeed more coal if there is hard work to do up ahead.

Note: Nominal Boiler Pressure is different for each locomotive type.

Note: Take care not to add excessive coal, as this will lower the temperature of the fire for a time. A great rule of thumb is "a little coal often", try between 2-4 shovels every kilometer (that's 3-6 shovels every mile).

Regulator

The Regulator field displays the current position of your regulator the range of values is expressed as a percentage (0-100%). The Regulator in conjunction with the Reverser setting determines how much and at what portion of the piston stroke that steam is sent to the cylinder. Together the Reverser (or Cutoff setting) and the Regulator act as the Train's throttle.

Cutoff

The Cutoff field displays the percent cutoff as dictated by the position of the Reversing gear and is expressed as a percentage (minus 75% to plus 75%). Negative values indicate the valve gear has been set to move the locomotive in reverse. The higher the Cutoff value the greater the duration of steam application to each piston stroke. Long cutoff, represented by higher percentage values (40 to 75%), maximize the tractive effort applied to the locomotive wheels. This is mainly used to get the locomotive moving from a standstill, accelerating away from a signal check, or when tackling an ascent.Short cutoff, represented by lower percentage values (less than 40%) are used to maximize the speed attainable by the locomotive during easy sections of the route.

Water

The Water field displays the percentage of the water in the 'sight glass' which is used to assess the level of water in the boiler. The water level should be maintained at around 60-70%. The injectors move water from the tender (or engine mounted water tank) to the boiler. Pumping water into the boiler can also be used to reduce the rate of pressure increase in the boiler as the thermal energy of the fire heats the incoming cool water.

Steam Chest

The steam chest is a chamber containing passageways used by the valves to distribute steam to the cylinders. The pressure reading for the steam chest can be used to gauge the rate of steam usage.

Coal level

Displays the level of coal in the firebox.

Steam Cab Controls

Steam Controls

To control a locomotive in Cab Mode you can either manipulate the various levers and handles in the Cab View with the mouse or you can use the keyboard shortcuts. If you want to operate the Cabin controls directly in Cab View, move the mouse over the various controls then click and drag to move the control into the appropriate position.

Note: If you are operating a consist with multiple steam locomotives you will need to control each locomotive individually in Cab Control mode.

Reverser (F/R)

The reverser determines the steam Cutoff and has a range of -75% to +75%. Negative values indicate the valve gear has been set to select reverse movement, conversely positive values set the valve gear to select forward movement. The neutral or mid-gear position (0% cutoff) prevents any tractive effort being applied to the locomotive wheels.

Regulator (W/X)

In Cab View select the required Regulator setting by moving the regulator lever to the required position (0 to 100%) or pressing the "W" key to increase or "X" to decrease.

Fireman (Space)

To stoke the fire by adding fuel, press the 'Space' bar. As the fire is stoked it burns hotter (red is a cool fire, white is a hot fire).

Lights (L)

Toggle the headlights on or off by moving the light switch or by pressing the "L" key.

Whistle (H)

To operate the whistle move the whistle lever or press the "H" key to operate the whistle. For long blasts of the whistle, simply hold the whistle lever or "H" key down. Some multi-tone whistles only have a single blast pattern.

Bell (B)

Toggle the Bell on or off by moving the bell switch or by pressing the "B" key.

Brakes

An introduction to the operation of the Westinghouse Air Brake can be found here

General Operating Principles

A Steam Engine needs a full head of steam to operate effectively. To generate the steam you build a fire in the firebox by shoveling coal through the firebox door found in the middle of the backhead. The backhead is that part of the boiler that makes up most of the front of the cab of the locomotive.

You must also have the boiler filled up appropriately with water. A hot fire and an empty boiler is a catastrophic situation. Maintaining the water level in the boiler is of great concern. The water glass in the engine shows you the level of water in the boiler. Try and keep it at about 2/3 of the way up the glass.

The Steam Injector is a precision piece of equipment which uses a venturi system to use high pressure steam to push water form the tender into the boiler under pressure through a check valve which only allows water into the boiler if the pressure behind the water exceeds the pressure in the boiler. Use the Steam Injector to bring the water level up to the right level and then turn it off.

Once the train is moving, the Steam Injector can be set carefully to just the right setting so that the amount of water entering the boiler matches that being used up as the steam is used to drive the train. If you have equilibrium here, the water level will be maintained at a given level. But as an engineer, you must continually adjust the flow of water as steam will be used up at different rates depending on the speed of the engine and how hard it is working which can vary dramatically with grades.

Another key control valve on the backhead is the Blower Valve. The Blower Valve is used to control a jet of steam that is blown up the middle of the chimney in the smoke box at the front of the steam engine. It accelerates the flow of air through the chimney pulling a strong draft through the firebox to keep the fires burning strongly. When the engine is moving the exhausting steam used from the cylinders that drive the train provide a good draft. But when the train is stopped or if you fire is not burning as hot as you would like, the blower can be used to maintain this draft through the fire.

The Reverser or Cutoff has multiple positions and adjusts the steam locomotive's valve gear in such a way that the pistons drive the driving wheels in the appropriate directions. In the center or neutral position, no tractive effort will be developed by opening the throttle. When first starting a steam engine, place the Reverser Handle in the full forward position. Once the consist is moving forward at a constant speed, bring the Reverser Handle back towards the short cutoff position, thus adjusting the valve gear appropriately for most efficient operation to preserve your use of coal and water. Move the Reverser Handle forward into the high cutoff range when accelerating or climbing grades.

The Reverser is used with the Regulator to control a combination of speed and tractive effort. Correct use of the Regulator is governed by factors such as the type of locomotive, the weight and length of the train, the severity of grades and weather conditions.

Opening the Regulator on a steam engine delivers steam to the valves which govern the distribution of the steam to the main cylinders which in turn drive the driving wheels through the main rods on each side of the engine. When starting off, it is good practice to advance the Regulator very gently. The finest of steam era engineers started their trains so smoothly that passengers hardly noticed that they were moving. It is also important to pick up the slack in all of the couplers along train. Once the slack has run out, the Regulator may be advanced as desired to suit operating conditions and the needs of the schedule.

To avoid wheelslip, start gently and use the sanders if required. Sanders deposit sand just in front of the driving wheels to improve traction. When decelerating, it is also important to consider the action of slack running in and out on the train. Always avoid reducing the Regulator quickly. Sudden changes in power propagate a wave motion throughout the train. This kind of surge increases the risk of drawbar or coupler failure, along with possible damage to loads or a very uncomfortable ride for your passengers.

Naturally gradients also affect the train so keep an eye on your speed and adjust the Cutoff/Regulator accordingly. On a positive gradient (uphill) you will begin to lose momentum, so you might need to lengthen the cutoff to say 40%. This is where it is important to maintain your boiler pressure as a longer cutoff consumes more of your steam.

If you are on a negative gradient (downhill) you may want to coast by reducing the Regulator to 0%, leaving the Cutoff at 20% and then touching the brakes to keep to the speed limit.

Note: When traveling down a hill, due care may be required to keep your train under control. When making a long descent, keep in mind that several successive brake applications and releases can result in depletion of the system, and it's therefore sometimes necessary to plan your approach to braking. It may be necessary to set a constant partial application to control your speed.