DISCLAIMER:

I do not work for Amtrak and had explicit permission to be in the two photographed areas on the Acela. The other pictures are from a GE 25 tonner, which I am specifically authorized to maintain and operate.

DO NOT TRESPASS ON RAILROAD PROPERTY/EQUIPMENT, AND DO NOT TAMPER WITH BRAKE EQUIPMENT OR TRAIN CONTROLS. THIS GUIDE IS FOR A VIDEO GAME AND IS NOT TO BE INTERPRETED AS A GUIDE OR LICENSE FOR OPERATION OF ACTUAL RAIL EQUIPMENT, IN ANY WAY.

Trespassers tend to get injured, killed, or jailed; and any railfan with any understanding of railroads will understand the dangers of trespassing, let alone tampering with equipment.There's a lot more going on than what you can see in terms of safety, awareness, and training, when you see railroad employees on the tracks or handling equipment.

===

Trains are big and heavy things that move quite fast, so some sort of brake is really a nice thing to have. From the very early days, this consisted of shoving something against the wheel to make it slow down; first wood blocks, then cast iron, and now stinky composite. Slow the wheel down and the train slows down; put brakes on every axle and you've got something that can stop several hundred tons from 50mph in maybe a mile or so.

(Sidebar: nothing happens fast with trains-- partly because of the weight; and partly because it's very easy to make the wheels break loose on the steel rails. Too much power or brake and the wheels will spin or slide, respectively, and won't do anything productive. There's a hard mechanical limit as to how much force you can apply in given conditions.)

The brakes were initially hand-applied on each car, by walking down the moving train and turning the brake wheels on the cars with a wooden stick. Steam locomotives sometimes had steam-applied brakes, but these often only acted on the drivers. The Brits liked to run "unfitted" trains with no service brake on the cars and a heavy brake wagon(s) with a handbrake; between the brake wagon(s) and the locomotive(s), enough heavy vehicles in the train had brakes to stop the whole thing. This also helped to control tension in the coupling chains, which really liked to snap if yanked on.

These are not ideal arrangements for a variety of reasons, and by the mid-1880s, Westinghouse (George, not the company yet) had brought out the "automatic air brake". This used air pressure to apply the brakes on each car and automatically (this is the only "automatic" thing about it, really) applied the brakes fully if the train split apart. This, along with the development of the knuckle coupler a few years earlier, led to significant improvements in safety and efficiency and allowed equipment to get much, much bigger. The Brits had the vacuum brake, which works similarly in practice but opposite in concept to the automatic air brake. Vacuum brakes were not generally fitted to freight equipment, though, and unfitted freights continued running into the diesel era.

Electric-transmission vehicles can also reconfigure their motors to make them run as generators; the energy from the train is converted to electrical current and the train slows down. If the current is sent to resistors and "burned off", this is rheostatic dynamic braking (just "dynamic braking"). If the current is fed back into the supply or into a battery, this is regenerative ("re-gen") dynamic braking.

This is an excellent arrangement, although it has the important caveat that it's a dynamic brake, i.e. the vehicle has to be moving at some speed for it to work. Modern equipment, particularly passenger, can maintain useful dynamic braking down to slow walking speed, while the dynamic brake becomes ineffective at higher speeds (running speed) on older equipment and road locomotives.

First off, I would recommend key commands instead of moving the handles in the cab. A real engineer knows where the handles are by feel and doesn't have to look down to find the brake handle. Light taps on the keys can make handling trains with very sensitive controls easier.

This is basic enough that I almost didn't include it, but I wanted to make sure I had everything covered:

Move train brake handle towards apply | '
Move train brake handle towards release | ;
Move locomotive brake handle towards apply | ]
Move locomotive brake handle towards release | [
Increase dynamic brake | .
Decrease dynamic brake | ,

Easy stuff. Many modern trains have no direct operator control over the brake system, with the computer taking care of blending the friction and dynamic brakes. Some of these have a combined power and brake handle, some have two levers, but it's set and forget (well, adjust as needed). Once the handle is in the brake range:

Increase brake | D
Decrease brake | A

This is reversed from power but it's intuitive. D to decelerate and A to accelerate.

Some US diesels with "desktop" control have a combined power and brake handle as well, although in this case, the brake range controls the dynamic brake, not the air brake.

With this type of control, you have to use both braking systems when stopping, although the air brakes are self-lapping (see below) and are basically set and forget as above.

Multiple units with a combined power and brake handle generally "blend" the air brake in as necessary, although the simulation of this effect varies widely.

As a note, some very old models don't simulate the brake system on U.S. equipment accurately and can be handled as "set and forget" as above.

In the following, remember this is steam-era technology and everything works mechanically...

The automatic air brake is the foundation for most railroad friction brake systems worldwide, with many systems all having the same general functions. This description relates to the U.S. freight application, which has some peculiarities.

The system works by charging a pipe (the train line), which runs through the entire train, with compressed air. Each car has an air reservoir and a brake cylinder on it. The car reservoirs are connected to the train line and brake cylinder through a device called a triple valve, which responds to pressure in the train line.

To apply the brakes, the engineer releases air from the train line, which causes the triple valves to disconnect the reservoirs from the train line, and apply pressure from the reservoir on the car to the brake cylinder, pushing the brake shoes against the wheels. Pressure keeps going to the brake cylinder until the triple valve detects the (now decreasing) pressure in the car reservoir has equalized with the (now lower) pressure in the train line, at which point it disconnects the car reservoir from the brake cylinder. The pressure in the brake cylinder is trapped, and the brakes stay on. The engineer can put the brakes on harder by releasing more air from the train line, which causes this process to repeat.

If the train snaps in half (and this happened quite a bit), or the engineer "big holes" the air, the pressure in the train pipe decreases rapidly. This rapid drop causes the triple valves to go into emergency, which applies a higher pressure from a separate section of the car reservoir to the brake cylinder. It also vents the train pipe at each triple valve to speed up the application and is accompanied by a loud, sharp release of air from the equipment (followed by screeching, rending and sparks if the train is moving at some speed).

In either case, we'll assume the train stopped, wonderful. How do the brakes release?

To release the brake, the engineer re-pressurizes the train line to a set pressure, usually 90 psi but sometimes a bit less. The triple valves detect that train line pressure is higher than car reservoir pressure; and move to both connect the reservoirs to the train line, and to release the brake cylinder pressure on each car. Once the reservoir and train line pressures equalize, the triple valves again disconnect the reservoirs and block the brake cylinder off.

An interesting wrinkle of this setup is that the brakes can be incrementally applied, but only totally released. If the engineer tries to increase the train line pressure "just a little", the brakes will release completely. The car reservoirs will then be charged to a lower pressure, and less pressure will be available for the next application. Repeatedly applying and releasing the brakes, without allowing train line pressure to return to normal, has a similar effect. On long trains, the train line can take a very long time to recharge, since it is feeding all of the reservoirs on all of the cars and may be thousands of feet long.

Passenger brake schedules usually incorporate "graduated release" which does allow for the brakes to be partly released. They also use a train line pressure of about 110 psi.

The status of the brake system is represented on the two duplex gauges visible to the engineer. The duplex gauges provide a variety of useful information that helps to monitor the train and control the brake:

The hand colors and their positions may vary, but these gauges will all display:
Locomotive main reservoir pressure
Equalizing reservoir pressure
Train line pressure
Brake cylinder pressure on the locomotive(s)

The gauges on the critter (red panel) are showing main reservoir charged, train line and equalizing reservoir equal and around 90 psi (so the train brakes are released) and locomotive brake cylinder pressure at 0, so the locomotive and train brakes are both released.

The gauges on the Acela are showing main reservoir charged, train line and equalizing reservoir equal at 80 psi and a brake cylinder pressure of around 50 psi. The Acela uses a higher train line pressure (110 psi), so here the brakes are fully applied.

The equalizing reservoir is essentially a "target" train line pressure, since the actual train line pressure will respond slowly on a long train.

So now we know how the train brake works and what it can do. How do we control it?

The engineer interacts with the brake using the automatic brake valve (train brake valve, engineer's valve):

The brakes on the entire train, including the locomotives, respond to this valve.

The valve handle has several notched positions, as well as ranges in which it can move freely. The handle is moved counterclockwise to apply the brake.

When the train is running (moving), the brake handle is left in the Running notch (duh). This connects the train line to a regulated feed, which maintains it at a set pressure, keeping the brakes released, or releasing them if they are applied.

Moving the handle counterclockwise, the next notch is sometimes Holding, which releases the train brakes but holds the brakes on the locomotive only. This is useful in some cases, although many real locomotives did not have this feature and very few TS locomotives do.

The next important notch is Lap. Lap is essentially an old-timey term for "valve closed". Nothing happens to the train line pressure in Lap, so the brakes will keep doing whatever they were doing before the handle was put in this position (i.e. holding a set application or staying released).

Beyond Lap is the Service Application range. As the handle is moved through this range, air pressure is released (slowly) at an increasing rate. This increases the rate at which the application is made but it does not affect the final pressure.

The engineer will make a pressure reduction by moving the handle into the Service Application range and leaving it there until the ER pressure is at the desired level, then returning the handle to the Lap position. If the handle is left in the Service Application range, the brake will continue to apply up to a full service application.

Beyond the Service Application range is the "big hole", Emergency. This notch connects the train line to, literally, a large port in the valve which vents to atmosphere. This causes a quick drop in train line pressure, triggering the Emergency behavior described above. The Emergency application will clear once the train line pressure returns to normal, but this can take a very long time.

If the handle were turned clockwise from Running, this notch is Release. Release connects the train line directly to the locomotive's main reservoir, which is a significantly higher pressure. This is intended to help build train line pressure when starting a long train from a stop. If the handle is left in this position, the train line will be overcharged. If the train line pressure returns to normal, the brakes will apply. A loud release of air comes from the valve when the handle is left in Release, as a reminder that the handle is in this position.

Self-lapping brakes, on the other hand, do not have a Lap position. The pressure in the train line corresponds directly to the position of the handle in the Service Application range.

In TS, labeling and function of some of these positions varies widely, and the most reliable way to figure out how to handle the brakes is to watch the gauges as you move the handle. With self-lapping brakes, the train line pressure should decrease with the handle position. With non-self-lapping brakes, the train line pressure in the service range will just keep decreasing. and it will drop faster as you move the handle. If this happens, handle the brakes as described above. Release may or may not be implemented as described, and this feature is generally not available on self-lapping brakes.

Brakes on TS NJT equipment for you Northeast US fans (including me) are NOT SELF-LAPPING. The game describes the handle positions confusingly in the F3 HUD, but watching the brake needles shows what's actually going on.

The brakes on the locomotive can also be controlled individually, as suggested in the description of Holding above. The engineer controls the locomotive brake through the independent brake valve:
This valve controls the brakes on just the locomotive(s). Most are self-lapping valves, moving the handle counterclockwise increases the brake application.

Non-self-lapping valves have Release, Lap and Apply positions and are handled as above, although moving this valve will affect the brake cylinders (and brake cylinder pressure on the gauges) on the locomotive only, not the train line pressure.

With the independent brake handle in release (its running position) and the automatic brake applied, the locomotive brakes will apply. The independent brake can be used to apply the brakes on the locomotive beyond this point, but it cannot release them in its normal service range. To release only the locomotive brake, the handle can be depressed, or pushed into a spring-loaded notch beyond Release. This is called "bailing off" the locomotive brakes, and is often done when starting to control slack in the train. The pictured valve does not have this feature.

Dynamic brakes (in this context) also act only on the locomotive(s). They're either controlled from a separate handle (power must be off) or from a combined power and brake handle. It takes a few seconds for the circuitry to reconfigure things when switching from power to brake.

Both the independent and dynamic brakes are useful as trim brakes, since the locomotives are pretty heavy and the train brake is very, very slow to apply and release. Dynamic brakes are particularly useful for sustained braking to avoid overheating shoes and wheels (which doesn't end well). The advantage of both is that they can be quickly adjusted by the engineer, while the train brake will take much longer to respond. Although overheating of brakes is not simulated, the locomotive brake should not be used over extended periods; notch up the dynamic or make another reduction for sustained braking.

Knowing which system to use when is all part of the fun and challenge.

Left hand gauge: White, train line; red, locomotive main reservoir
Right hand gauge: White, locomtive brake cylinder; red, equalizing reservoir ("target train line")


What state are the brakes in here?

Train brake released, independent brake applied; train line and ER are high, but so is cylinder pressure


How about here?

Train brake applied; train line and ER are low and cylinder pressure is high. Cylinder pressure is high enough that independent is also applied; full service on the train brake has the train line and cylinder pressures equal, around 50 PSI. Emergency has cylinder pressure higher than train line, but train line pressure is 0 in Emergency. Also low main reservoir pressure, I mean, the thing's 78 years old (we've fixed the MR pressure since this was taken).

-I have no idea what the "brake difficulty multiplier" hotkey does, it's never made much of a difference when I've tried it. I'd imagine it probably just speeds up the rate at which the train line pressure can change on the "easier" settings. Real locomotives do not have a button that makes the brakes more difficult to use.

-As noted above, the accuracy of the brake simulation varies WIDELY between equipment, TSW2 (and I'd assume 1 and 3) are generally much better here but you're buying into the walled garden. TS20xx/Classic/whatever is pretty damn good if you get a well-scripted asset, but you can tell there's less going on under the hood by default.

-If you have problems with older British non-steam locomotives (not EMUs/DMUs or modern stuff) not braking, like, at all, look at the locomotive brake cylinder pressure gauge and TRY THE INDEPENDENT BRAKE!

Many of the earlier British diesel and electric locomotives were dual-braked, with vacuum for the train and air for the locomotive. The scripting required to simulate a mechanical valve was apparently too much for some devs (mainly those one letter over from "C-S-F"), who threw up their hands screaming "IT CAN'T BE DONE!"

In my experience (and my specific complaint is with the BR diesel hydraulic pack), it can be done, and often is, within the same pack. The brakes on the Class 42 work fine, the locomotive brake comes on with the train brake and the gauges seem to work. The Class 35 has no indication of train brake status but the train brakes work. Both the 35 and 52 require the driver to apply the train and locomotive brakes to stop in less than five minutes. The locomotive is heavy (which is simulated), so it can apply much more force at the rail than a car (carriage, wagon, van). If the locomotive brakes don't work, the train loses a very significant portion of its total brake force.

-Pictures in this guide are real, mine, and are not to be reproduced for any commercial purpose without express permission. Title photo is the back of the brake rack/reservoirs from an Acela power car.

=====

Hopefully, this guide was interesting and taught you something about how brakes on "real trains" work. I might expand it further to include vacuum brakes and it definitely needs more pictures.

If you read the whole thing and were actually interested the whole time, consider getting involved in your local rail preservation scene. Juicy technical morsels are all yours for the hunting and picking, then; and you'll probably get to do some stuff you think is cool.