Daily Archives: December 21, 2015

A Primer On Emergency Maneuvers – Part III

Welcome to the second-to-last installment of our three-part series, A Primer On Emergency Maneuvers. We’ve covered a lot of ground up to now, and are ready to finish it out with a bang.

So far we’ve covered watching for other vehicles, off-road recovery and emergency stopping. Our next area of focus will be on brake failures. So let’s get right to it!

Brake Failure

Don’t worry, your brakes are safe. The fact is, a well-maintained brake system rarely ever completely fails. Despite this, however, brake failures do occur, so you need to be ready just in case it happens to you.

What happens when your brakes fail? The eventual loss of control of the vehicle. Like any other emergency situation, the most important thing is to keep your cool and do your best to bring the vehicle under your control.

There are generally four types of brake failures:

  • Loss of air pressure;
  • Air blockage;
  • Brake fade;
  • Mechanical failure.

Let’s start with the first.

Loss of Air Pressure

You should immediately hear a warning buzzer, tone or light (or combination thereof) when air pressure gets too low. You should stop immediately once this happens.

Fortunately, your brakes should automatically apply when air loss reaches a critical level. Keep in mind that whenever things go as planned, air loss can happen very quickly. Also remember that the independent trailer brake won’t function, as it depends on the air system.

If the vehicle is equipped with spring-loaded parking brakes, they will usually engage when air loss creates critical situation.

Air Blockage

There are a number of different ways that an air blockage can prevent air from reaching the brakes. But most commonly this is caused when moisture gets into the duct system and freezes. It could also occur if dirt somehow makes its way into the system.

Brake Fade

If you thought long downgrades in a passenger vehicle are bad on brakes, try heading down a huge hill in a big-rig truck. On long downgrades, brakes may overheat or “fade.” When this happens they will lose their ability to retard the wheel rotation. CMV brakes also don’t cool as quickly as personal vehicle brakes, due to their size and composition.

Mechanical Failure

When there is a failure in the linkages that connect the control system, brake failure can occur. Fortunately, on CMVs, rarely will all the brakes be affected at once. Generally the CMV will still be able to be brought to a complete stop.

So what can you do if you encounter any one of these brake failure situations? With a cool, calm, collected and educated response, your safety won’t be at stake.

Brake Failure General Procedures

If your vehicle’s brake system fails, immediately implement the following procedures:

  • Downshift: If you are driving on a relatively flat road, downshifting will help slow the vehicle down. Immediately start transitioning into lower gears to reduce speed. Get your vehicle to a low enough speed that you can safely deploy the parking brake. If you are on a downgrade, do not try to downshift.
  • Escape route: While you are attempting to slow the vehicle, immediately begin looking for an escape route. Escape routs can be anything from open fields to side streets or escape ramps. You can also turn uphill to slow your roll. If you come to a stop, remember to apply your parking brake so that you don’t roll backwards.

If you are on a downgrade and your brakes fail, you will have to look outside your vehicle for a method of slowing it. If there is an escape ramp, take it. They often are composed of gravel or sand and help to dramatically slow the vehicle.

Just remember to immediately look for a way out once you realize your brakes have failed. The longer you wait, the harder it will be to stop. Once you’ve done that, join us for our final installment of our emergency maneuver series, where we examine blowouts.