Brakes

Brakes are devices employed on locomotives, cars and other vehicles, used to slow down, stop, or immobilize them.

## Handbrake

Simple mechanical handbrake, found on all rolling stock. Fully applied when rotated to the right (5'o clock position), released when rotated to the left (7 o'clock) The handbrake is intended for keeping locomotives/rail cars in place when already stationary and should only be used to slow a moving train in dire emergencies.

All single or group rolling stock spawned by the game will automatically have a handbrake applied at either the first or the last vehicle (this can include the locomotive when spawning trains in sandbox mode). All locomotives spawn with their handbrakes fully applied.

## Independent Brake

The independent brake, sometimes called the locomotive brake, uses compressed air from the locomotive's main air reservoir to directly apply pressure to the brakes. It only applies the brakes on the locomotive itself (or a group of locomotives linked as multi-unit) rather than the entire train. The independent brake is much more responsive than the train brake and is the preferred form of braking when you are driving the locomotive(s) alone with no cars; in a full train the results will be barely noticeable (as you are only braking few wheels on the entire train) and when applied too hard will result in wheelslip.

## Train Brake

Rolling stock in Derail Valley use the Westinghouse air brake[1] system, where braking is applied by releasing air pressure from the brake pipe, after it has been built up in air reservoirs, using triple valves.

While this may sound complicated, the rules of operation can be simplified as such:

* All newly spawned locomotives and cars have no pressure in their air reservoirs and therefore no train brake. They are only held in place by their handbrake.
* Once a car is connected to the locomotive through the brake hose, the train brake will engage (indicated by the red needle on the brake pipe dial) and then slowly release as the pressure in the brake pipe builds up.
* When the brake pipe is fully pressurized, the brakes are fully released. From this point onward, releasing the pressure from the brake pipe will apply brakes and charging it back up will release them.

The train brake releases air from the entire brake pipe, applying brakes on the locomotive and every connected car. While the air can be released (and therefore brakes applied) reasonably quickly, it will take much longer for the brake pipe to pressurize back up and therefore for the brakes to be fully released again. The effect scales up with the number of cars in the train and down with number of locomotives (as they pool their air reservoirs/compressors together to fill the brake pipe back up)

Train brake is the main method of slowing and stopping trains but in practice, it means for optimal driving you will need to disengage the train brake "ahead of time", *before* the train slowed down to the required speed, as the braking effect will persist for some time afterwards.

If you disconnect a car with built-up pressure in its air reservoir/brake pipe, it will eventually dissipate on its own. You can release it manually using the air hose valve (for the brake pipe) or the red pull-handle found somewhere on the car (for the air reservoir once the brake pipe is empty).

### Non self-lapping brake

The older locomotives (DM3, S060, S282) have non self-lapping brakes. This means that the train brake lever does not directly control how much brake is applied (e.g. 50% brake lever application means 50% brake application); rather, the brake lever is used to manually control the increase or decrease of brake pressure. There are four positions: release, which releases the brakes; hold, which holds current brake pressure; apply, which steadily increases brake pressure; and emergency, which rapidly increases brake pressure and requires the driver to hold the brake lever all the way forward.

## Dynamic Brake

The DH4, DE6, and DM3 have dynamic brakes, which apply braking to the wheels directly through the drive train. This slows down the locomotive/train without applying the brake shoes. Dynamic brakes are generally only useful at higher speeds and have similar limitations to the independent brake. Dynamic brakes are best used to control downhill speed (the faster the train goes, the more braking is applied, and thus a point of equilibrium will be reached at a certain speed), or in conjunction with the train brakes to slow the train down even faster than if just train brakes were applied.

### Countersteam Braking

Although not technically a kind of dynamic braking, countersteam braking operates similarly, in that it applies a slowing effect through the drive train without the use of brake shoes. Countersteam braking can be done only on the steam locomotives (S060, S282), and is performed by moving the reverser to the opposite direction of movement and applying throttle. Countersteam braking is very effective and more predictable than dynamic braking, since its effectiveness does not vary with speed, but rather with reverser and throttle setting.

## Brake Heat

On a moving train the brakes heat up when used, proportionally to how fast you're going and how hard you're braking. There is no indicator for brake temperature in the cab, but hot brakes will visibly glow, emit a loud whine when used, and, most importantly, lose effectiveness. They will slowly cool down on their own when not applied. Brakes do not suffer any permanent damage from overheating. Dynamic brakes can be used to mitigate, or entirely negate, brake shoe overheating when performing extended braking on downhill slopes.