Steam Locomotive Operation

OVS Training Institute 2006






















In our Basic Train Operation course, we showed you the basic operation of steam locomotives, with the "Automatic Fireman". In this course we take a deeper look into how a steam locomotive works, and how to "fire" them. Many proficient steam engineers soon find running a diesel "mindless and boring".

You need to be certified in Advanced Train Operation before starting this course

Disclaimers: Only information that is relevant to MSTS is included. For example,  turning on and off pressure maintainers, or adjusting the air compressor output, is impossible in MSTS and would just cause confusion. If interested, further information can be found online and in railroad literature.

The steam locomotives in Microsoft Train Simulator behave slightly differently to the prototype (real ones). While very similar, this training will not make you proficient at firing a real locomotive.

Steam power

Steam power ruled the rails for over 100 years. Even today, it is used in certain parts of the world, and in tourist trains. Despite the economy and convenience of the diesel electric locomotive, railfans are still drawn to the romance of the steamers.

Steam works by rapid expansion. When water is heated to its boiling point and converts to steam, it expands many times it's density as water (liquid). This expansion can be used to do work. It can be used to turn fans (turbines), like the ones that turn electric generators, or to drive pistons, like on a locomotive.

Firing a steam locomotive is simply boiling water. Driving a steam locomotive is simply putting that steam to the pistons. Sounds simple, huh?

How a steamer works

A steam locomotive is very simple. And very complex.

A coal (or oil) fire in the firebox heats water to boiling. The steam expands and pressure builds pressure. When the regulator in the steam dome is open, steam goes through it and into the cylinders. A valve determines whether the steam goes in the front of the cylinder or the back, driving the piston one way or the other. The steam then goes into the smoke box and out the stack.

Nothing to it, right?

We went over basic steam locomotive operation in our Basic Train Operation course. This will get you through most activities with the Automatic Fireman. This course will give you a much better understanding of how to run a steam locomotive. It's a balancing act,  with several factors to keep a wary eye on.

Boiling water

Running the boiler is probably the most confusing part of Train Simulator. There's a lot to keep an eye on, and steaming a locomotive, like driving one, is a balancing act.

The first part of firing is the fire.

The Fire Mass is how heavy the fire is. Each steamer has an "Ideal Fire Mass", ours are listed on the Motive Power Rosters. Staying within a few pounds of this weight will give you the best working fire. When the Fire Mass starts to get too low, you build it back up by shoveling in more coal. First you open the firebox door using the [F] key. Open it 100%. Then increase the shoveling rate with the [R] key. If you keep the Fire Mass close to the Ideal Fire Mass, you will only need the minimum shoveling rate to maintain it. MSTS doesn't allow us to accurately adjust this. You just gotta keep working with [R] and [SHIFT] [R] to get it down where you want. If you're not using a lot of steam, a setting between 4 and 15 works well, if you can get it to stop in there.

If you allow the fire mass to get too high, you "drown" the fire. The burning coal gets buried by non burning coal, and can't get any oxygen. Your steam generation rate drops like a rock. If you get too much fire load, decrease or stop your shoveling rate, and use as much steam as possible.

Fire Temperature is the second part of balancing your fire. If you let the temperature get too low, you won't make much steam. If you let it get too high, you will melt the fusible plugs (which try to protect you from the dreaded boiler explosions) which dump water from the boiler onto your fire, putting it out. Effectively ending your trip.

You can use several controls to regulate your Fire Temperature. If it gets too high, you can either shovel coal onto it (if needed, based on fire mass), or you can close the damper. The damper is the air inlet below the fire, the more air coming through the damper, the hotter the fire. It's usually 100% open. If the Fire Temperature gets too low, you can stop shoveling coal (depending on Fire Mass), make sure the damper [M] is open, and using the blower. The Blower [N] shoots steam up the stack creating a vacuum, which draws more air through the fire. Usually when the locomotive is moving, enough steam is exhausting through the firebox up the stack to draw enough air through the fire, but sometimes the Blower is needed. The blower often seems to cause a big increase in steam generation, but not much increase in fire temperature. Steam locomotives usually work best with a Fire Temperature between 900 and 960'.

The next part of firing, and probably more important, is the water lever.

Water level can be seen in the sight glass, (the default cab view has a second site glass with tender water level) and on your Heads Up Display. Too much water in the boiler and it won't heat up quickly enough to generate enough steam. It can also cause Priming (water collecting in the cylinders). Too little water in the boiler and the crown sheet (the top of the firebox/bottom of the boiler) will overheat and cause a boiler explosion. A boiler explosion levels everything within several hundred feet, starting with the engine crew.

Water goes into the boiler through two injectors. The injectors both use steam to pull the water through the injector into the boiler. Both injectors just trickle the water in by gravity unless you turn on the steam to them. They are turned on by pressing the [I] and [O] keys, or using the controls if they are provided.

The Intake Injector or Live Injector, Injector 1, uses steam from the boiler itself. So it's a constant supply of steam. You can set this injector to set your "base" water level, that will maintain a safe water level with the throttle closed. Turn the injector on with the [ I ] key. Increase the injected water with the [ K ] key and decrease it with [SHIFT] [K]

The Exhaust Injector, Injector 2, uses steam being exhausted from the cylinders. So it will not work at all with the regulator closed, and will operate when there is steam going through the cylinders. This injector can be set to maintain a safe water level while using steam. Turn it on with [ O ] and increase the water with [ L ], decreasing it with [SHIFT] [L].

Both running and sitting, you want between .6" and 1.0" of water in the boiler.

Keep in mind, the boiler sight glass is at the back of the boiler. When going uphill, the sight glass will read more water, as the water moves to the back of the boiler. So you want more water in the sight glass than normal, keeping the front of the boiler covered with water. If it reads normal, the front of your crown sheet might not be covered with water. Going downhill, just the opposite happens, the water in the sight glass drops because the water moves forward. Keep the level up, or the back of your crown sheet will not be covered with water. Your top priority is keeping the crown sheet completely covered with a safe amount of water, which prevents your trip having an explosive ending...

By regulating the fire mass and temperature, and your boiler water level, you can do a decent job of maintaining your steam pressure. Your steam pressure can be seen on the Boiler Pressure gauge, and in your Heads Up Display. Too much pressure and you blow the pressure relief valve, wasting steam. Too little pressure and your train will come to a stop long before you want it to.

The steam Chest Pressure gauge shows how much pressure is in the cylinders. It goes up and down with the regulator, if you're making adequate steam.

You can help maintain pressure with several controls. Not all controls will be needed in most cases, but they're all listed to give you a choice.

If you have too much steam, open the regulator a bit more, turn up the water injectors which raises the water level and uses steam, and reduce your fire load. You only want to produce enough steam that you're going to use. The Ideal Fire Load listed in the roster is for maximum steam generation. On the flat, at speed, let your fire burn down, maybe even to half the roster rating. Just watch your fire temp, shut off the blower and close the damper to about 90-95% to maintain a 900-960' fire.

If you don't have enough steam,  work your reverser and regulator to produce more steam than you use. Crank up the blower [N]. You can gain a little steam by turning off the water injectors (unless your water level is low), turning off the braking system air compressor [ J ], and turning off the steam heat [SHIFT] [ U ]  on passenger trains.  Just remember to turn your compressor back on or your brakes will never release.

Tunnels are also a problem when firing a steam locomotive. According to Microsoft, in a tunnel, there will be a "blowback" of the fire if you leave the firebox open. While not prototypical, it is something you have to keep track of. Knowing your route is very important, planning on when to add coal to avoid tunnels. Keeping your firebox door shut when not stoking the fire helps. Even if the door is open 1%, you will get blowback, so when approaching tunnels, I like to [SHIFT] [F] to make sure it's shut.

Putting steam to piston


Default Cab View
Controls underlined are used with Automatic Fireman

The engineer has two controls to use the steam to move his engine and train. While similar to the Throttle and Reverser on a diesel, they operate very differently.

The Regulator is similar to the throttle on a diesel. The diesel throttle controls the amount of diesel fuel going into the cylinders to be burned, moving the piston. The Regulator controls how much steam goes into the cylinder to move the piston.

Most MSTS steamers actually have two valves in the regulator controlled by the regulator bar, called a "Twin Port Regulator". The First Valve is smaller and lets a limited amount of steam to the cylinders. It's used for starting a light train, and maintaining a constant speed. The Second Valve is bigger, giving more steam pressure to the cylinders. The Second Valve is used when you need P O W E R ! ! ! In MSTS, the First Valve operates from the 1% to 49% setting, the Second Valve operates from 50% to 100%.

The Johnson Bar, or Reverser, lets you make the locomotive move forward or backward. Set the Reverser set at full forward (75%) when you really need a lot of grunt. You set the Reverser back as you gain speed. Setting it back uses less steam. Less steam means less coal and water.

How it works is when you have the reverser at full forward, steam is being forced into the cylinder over most of the piston stroke. You are using the boiler pressure to drive the piston. Lots of power, but you're using lots of steam too.

When you set the reverser back, steam is being forced into the cylinder for less of the stroke. The steam in the cylinder then expands, driving the piston. It doesn't generate as much grunt power, but uses a lot less steam. Enough power to maintain speed and even accelerate a moving train in most conditions, it also saves coal, water, and your fireman's back. You can also build pressure for a climb or a coming restart after a quick stop.

When you're using more steam than you can produce, your pressure drops. Of course if your pressure drops too much, you're stopped. Some guys monitor how much coal and water they use, the less coal used, the better. You want to work with the least amount of regulator and reverser to stay on schedule. You have to experiment with the regulator and reverser settings, watching your speed and projected speed in your Track Monitor (F4), and watching your Steam Generation Rate and Steam Usage Rate in your Expanded Heads Up Display (F5 F5). Use more steam than you generate, and your trip will be short. Remember the twin port regulator? Watch the difference in steam usage with the regulator set at 49% and at 51%, using a setting over 50% often saves you steam.

You can get away with using more than you generate for a short period of time, but if you're heavy and your going up a long grade, you better be working your reverser AND your regulator. Changing either changes the amount of steam used, and it also changes how much steam you produce. The more exhaust, and the higher the steam pressure coming out of the blower (if used), the more draft your fire has. Train speed seems to have an effect also, effecting the amount of wind going through the damper. Lowering your steam usage also lowers the amount of steam you produce.  You don't NEED to know why the steam generation rate goes up and down, just watch it as you watch your steam usage rate. You find the point where you produce more than you use. Then, you can maintain or even start building your chest pressure again instead of using it up.

Each steam locomotive is different, even with the same wheel arrangement and class. Just like in real life. Railroads have a "company mark" where you set the reverser for best performance and least amount of water and coal used, called the "company notch".  The MSTS steamers have a "company notch" set at about 40%.

Remember from the Basic Train Operation course, if your unit has been sitting for a period of time, open the cylinder cocks before starting. After a couple of strokes, you can close it. The reason is steam remaining in the cylinders condenses (converts) back to water. Water in the cylinder is a bad thing. Water doesn't compress, so if there's water in the cylinder, it will cause too much pressure and the cylinder can explode.

Water can get into the cylinders while it's running, this is called priming. Priming occurs when you have too much water in the boiler. The only way you can detect priming is in the last line on the Heads Up Display, unless you are experienced enough to notice the drop in power. Open the cylinder cocks to clear the water priming, and reduce the amount of water in the boiler.

Driving a steamer

You've already driven a steamer with Otto Fireman on board, so you know that except for what we talked about, it operates like a diesel locomotive.

Unless you have paid close attention to the brakes on a steamer. The brakes on most diesels are "self lapping".  You set the brake handle to the amount of braking you want, and you forget it. Well, the self lapping brakes opens the brake valve all the way, until the pressure in the system drops to a certain point. It then closes the valve, and maintains that pressure in the system. You can move that handle back to "Lap 0%" and it will still maintain the same pressure. That's a simple explanation of "lapping".

Well steamers, some early diesels, and electric cars and locomotives do not have self lapping brakes. When you move the brake handle, you are opening the brake valve by the percentage noted. When you move the handle to 25% on most diesels, you get 25% brake strength, and you probably never pay attention to the brake gauges. When you move the brake handle to 25% on steamers, you open the brake valve 25%. It's like opening your faucet on your sink 25%. It does not regulate the pressure, if you leave it at 25%, it will eventually allow all of your air to escape, stalling the train. With steam, you have to watch your brake pressures.

If  you want a 10 pound reduction, you move the brake handle. If you want a slow reduction, only open it up a little. If you need a faster reduction, open it up to a higher percentage. When you have reduced the air to where you want it, move the handle back to the "LAP" position. The pressure will drop no further. To regain the pressure and release the brakes, move the handle back to the RELEASE position and the pressure will build back up.  If you are slowing too much, move the handle to the RELEASE position until you get the pressure built up to where you want it. For example, if your ten pound reduction was too  much and you want to try a 5 pound reduction.

Some locomotives have a RUNNING position, which operates the same way as the LAP position. Some have a gradual release, the brake release can be set to 1-100% RELEASE. That's handy if you want to release your brake pressure some, without completely releasing them. It can also be a pain if you need to release the brakes quickly to prevent stalling the train. A very few have LAP positions from 1-100%, though nobody knows why.

Non-self-lapping brakes, like firing the locomotive, takes practice to become proficient.

Refueling the steamer uses the same key as the diesel, the [ T ] key. You have to be properly lined up with the water pipe to refill the water, and the coal chute to refill the coal. The fueling facilities must be activated by the activity developer for the fueling stations to work.

Remember, firing a steam locomotive is simply boiling water. Driving a steam locomotive is simply putting that steam to the pistons. The trains weight and the grades of the route make it complicated. Every train and every route will be different. Once you know the basics, NOTHING BEATS EXPERIENCE!!!

Running a steamer can be very aggravating, especially until you get that experience. But once you have it, nothing else compares. You will find yourself in a diesel on a long road trip, bored to tears. With steam, there are no boring runs, at least that we've found. You're either trying to maintain the balance, or working on efficiency. And if you're ahead of the game, sight seeing along the way.


Wrapping it up

These are the values you are shooting for:

Regulator (throttle) and Reverser: Set for desired speed and steam usage
Boiler Pressure: Listed on the roster, try to stay close to max without setting off the pop-off valve
Steam Chest Pressure: Depends on your throttle setting and boiler pressure
Boiler Water Level: Maintain between 0.6 and 1.0 unless you are on a grade

Steam Generation Rate: Depends on your firing parameters, train speed, and throttle and reverser settings
Steam Usage Rate: Try to keep this value below the Steam Generation Rate unless you know you can climb a grade before runing out of steam
Cylinder cocks: Closed unless starting a loco that has been standing for a long period of time, or to clear Priming
Loco Brake: Should be 0% unless you are using the Independant Brake
Compressor: Should be on, unless you are really desperate for steam. The compressor recharges the brake system.
Steam Heat Pressure: Can be turned on in cold weather to heatpassenger cars. Uses a little steam.
Water, Tender Coal: Usually not a concern
Blower: Increases steam generation, also increases fire temperature
Dampers: Used to regulate fire temperature, usually between 94% (not shovelling) and 100% (shovelling coal)
Firebox doors: Open 100% to shovel coal, and to help cool a fire, must be closed in tunnels
Fire Temp: Try to maintain a fire temp between 900' and 960'
Injector 1: Should be on (100%)
Injector 2: Should be on (100%)
Injectors (Water): Controls exhaust powered injector. Adjust water level under throttle
Injectors (Steam): Controls live powered injector. Adjust water level with throttle closed
Priming Level: Should be 0%

Always remember, if you have any questions, just ask. Even the most experienced and knowledgeable are still students of steam.