How Brake Failure Works

The brake system of a car. See more brake pictures. Alim

The car starts and the car stops. As drivers, we need both of these features as much as we need to breathe in and out. If you've ever been in a vehicle that did not stop, you know the sheer terror that brake failure can cause. Whether your vehicle is equipped with disc or drum brakes, you expect them to work when you hit the brake pedal.

Brakes can't talk -- or can they? If you're not distracted with chatter or music, you might hear your brakes trying to tell you when something's wrong. Brakes have their own language; they squeal, click, squeak and grind. You need to listen carefully to their noises rather than ignore them and hope the sounds will magically disappear.

The easiest way you can avoid brake failure is by maintaining the vehicle regularly and being attentive to any changes in performance. Because a vehicle's brake system involves many components along the entire length of the vehicle, any number of things can go wrong. Calipers, drums and brake pads, oh my!

­Let's say that despite your attentive care of the vehicle, the brakes begin to fail. What dangers might you and your passengers face, and how can you prepare for them? What will you do if you are towing a boat or trailer and experience brake failure? How can a runaway truck ramp help if your brakes stop working? In this article, we'll investigate the answers to these questions, explaining everything you need to know along the way.

First, let's stop a minute to examine how brakes work and what causes them to fail.


Brake Failure Causes

Before you can understand brake failure, you must understand how brakes work.

The brake system is rather like this children's song verse, "The head bone's connected to the neck bone, the neck bone's connected to the shoulder bone ..." In vehicles, the brake pedal is connected to the pistons, and the pistons are connected to the brakes. Most modern cars have disc front brakes and drum rear brakes.

Functioning brakes stop a vehicle by using friction. In this way, they are unlike the engine, which must always be kept lubricated to run smoothly. In front brakes, friction stops the brake calipers and pads. In rear brakes, friction hits the brake drums and shoes.

Several factors can interfere with this friction and lead to brake failure:

  • Grease or oil on brakes causes brake failure, because it interferes with friction. If oil leaks, it may indicate that an oil seal has failed.
  • When the brakes overheat to a great degree, the metal in the brake rotors or drums develops hard spots. These are known as hot spots. The hot spots resist the friction from the brake shoes and pads. Because the shoes or pads have nothing they can grasp, there's no friction. Consequently, braking power is lost.
  • Brakes that squeal indicate that the brake pads are wearing thin. By the time the brakes begin making a grinding sound, they've worn down past the pads to the rotors, which will cost more than pads to replace [source: Gray].

Do you know anyone who nervously "rides the brake" when driving? How about the scaredy-cat driver who often stops in a panicked way? This type of driver is headed for crystallized brake pads or shoes. Because of the heat generated over repeated overuse of the brake, the pads and the shoes grow hard and are ineffective. Brake material has to be flexible and able to grasp the disc or drum in order to stop the vehicle.

Now let's look at the dangers a driver faces when brakes fail.

Dangers of Brake Failure

Brakes function because of a special hydraulic, or liquid-based, system. Brake fluid moves from the pedal through the brake-line system. Because liquids can't be compressed, they move. It is this movement that pushes against the mechanism that stops the vehicle. So when this fluid runs low, brake problems will occur.

If the brake system is failing, the vehicle may pull to one side. This situation can cause accidents that range from fender-benders to serious collisions. You might also feel pulling if there's been a leak of brake fluid, if the brakes aren't adjusted properly or if the brake has locked. [source: Grey].

The most apparent danger in brake failure is the possibility of injury or death. As a result, it is important to wear a seat belt and to be certain that guidelines for infant and child car seats are met to ensure safety. Don't forget to be alert to and aware of pedestrians on or near the roadway.

Another concern is property damage. This includes the vehicle itself but also trees, power lines, highways signs and telephone poles. Damage to private or public property will need to be compensated, which can affect your auto insurance premium.

Don't let the dangers of brake failure frighten you. Read on to learn what you can do in the event of brake failure.

How to Handle Brake Failure

Complete brake failure in modern vehicles is rare, but it can happen. This can be the result of a defective brake system from the manufacturer, so pay attention to recall notices. Total brake failure could also occur if all the brake fluid has leaked out. Fortunately, most of us would notice either a leak or a sound before that happened.

One common temporary brake failure occurs when the vehicle hydroplanes. This happens when the brakes are wet, usually after driving through a deep puddle. If you experience this, remove your foot from the accelerator. Hold the steering wheel straight. Do not swerve or jerk the vehicle. This way, the vehicle will slow down and you can regain control of the car [source: Midas].

Perhaps the most important action a driver can take when the brakes fail is to remain calm. Panicking doesn't help. The next step -- the first action step -- is to lift the foot from the accelerator. Notice the flow of traffic and any obstacles or pedestrians, and look for a place to pull over safely. Then try downshifting to a lower gear, whether your vehicle is an automatic or a standard. This is called engine-braking. As the vehicle slows down, keep shifting to lower gears.

Once the vehicle is moving at 30 mph or less, you can try engaging the parking brake. Because it is a separate system from the regular brakes, it should still work.

As a final resort, put the car in reverse. But remember, this could destroy the car, so never use it as a first response.

Try to maneuver the car off the road if possible as you come to a complete stop. Turn your hazards on and call or wait for help.

We've discussed dealing with break failure in your car - but what if more than your car is involved. What if your brakes fail while you're towing something? Read on to find out.

Brake Failure While Towing

You have the afternoon off and decide to spend it at the lake. You're pulling the boat behind your pickup, when your brakes suddenly fail. What happened? And what can you do?

Trailers go out of control if they are pushed beyond their maximum speed. Even good drivers can lose control if the road surface is rough, or if there's a sudden strong wind or drag caused by a passing vehicle. Needing to maneuver a vehicle suddenly, to avoid a collision or an obstruction in the road, can also cause a lack of control. Remember -- always operate the vehicle at a safe speed.

Starting and stopping a vehicle with a tow trailer must always be done slowly. It takes more time to stop your vehicle when you've got a trailer attached. Plan for twice the time and distance you would need without a trailer. Looking ahead and anticipating stops is another smart way to drive. That way, you won't need to hit the brake suddenly. The trailer may jackknife if you hit the brake in a panic. If that happens, or if the trailer appears to be playing tag with your rear bumper, remove your foot from the brake pedal [source: DMV].

Overheating can result from overusing the brakes. Use lower grades when going down a hill. This will allow engine compression to slow and stop the vehicle.

In the event of brake failure, especially in mountainous regions, runaway truck ramps are your best bet. Let's look at them in more detail.

Runaway Truck Ramps

Runaway truck ramps, also called truck escape ramps or TERs, can be found on highways that traverse steep downgrades. Contrary to what their name implies, TERs aren't just for folks driving big rigs. Drivers with overheated and malfunctioning breaks mainly find runaway truck ramps useful in two situations:

  • When braking problems arise in regions of heavy traffic and population on short but steep hills
  • In sparsely inhabited mountain regions on long grades [source: Dragnet].

For more than 40 years, runaway truck ramps have been constructed in areas where frequent accidents involving big trucks have occurred. They may also be used as a preventative measure to keep children riding on school buses safe. Although they can be constructed anywhere, they are most often located in mountainous states.

When designing runaway truck ramps, engineers must consider the width of a vehicle as well as its weight and the approximate speed at which it might be traveling. One design is known as the gravel arrester bed. Studies have determined that these beds are more effective in slowing and stopping vehicles if rounded gravel from riverbeds is used, rather than crushed gravel. Another method used to construct TERS is to stretch a series of nets formed from aircraft cable across the ramp. The nets are fitted with energy absorbers that are mounted on both sides of the ramp's concrete walls. The use of these nets helps to stop vehicles and reduce the impact of the force created by slowing down, or decelerating. One company has designed a ramp that can stop vehicles traveling as fast as 90 mph and weighing up to 90,000 pounds! [source: Transportation Research Boards]

When gearing down or using the parking brake doesn't work to stop your vehicle, you may be able to pull into one of these truck escape ramps. They're usually located to the right of the roadway.

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More Great Links


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