Have You Checked Your Brakes Today?

August 31, 2013

Truckers are required to check their brakes daily, but that doesn't always happen. In a matter of a few minutes a driver can easily adjust air brakes equipped with manual slack adjusters It is the opinion of professionals in the enforcement, regulatory and training business that the primary causes for drivers not adjusting brakes is a lack of education.

In the upcoming week drivers will be able to get instruction on how to inspect and adjust their brakes properly.The week of Sept. 8-14 is Operation Air Brake/Brake Safety Week, an international truck and bus brake safety campaign dedicated to improving commercial vehicle brake safety throughout North America.

Over the past few years there has not been a significant change in the rate of vehicles taken out of service for poor air brake adjustment or other brake-related defects. Traditional enforcement methods, through the North American Standard Inspection Program by themselves, are having a reasonable impact in helping to remove dangerous vehicles off the road, according to the Commercial Vehicle Safety Alliance (CVSA). However, much more needs to be done.

In order to reduce the out of service rate for brake defects, CVSA began this more comprehensive campaign. The Selective Traffic Enforcement Program (STEP) model has been used successfully in other areas of traffic concerns (most notably seat belt usage), and it was expected that a campaign using this model would be effective in addressing the issue of brake defects. The Operation Air Brake Campaign was developed and initiated by Canada in 1998.

Out of adjustment air brakes and brake system defects constitute the major defect areas resulting in commercial vehicles being placed out of service. Poorly adjusted or defective air brakes reduce the braking capacity for large vehicles and further inhibit their stopping distance. Under ideal conditions, the braking capacity of commercial vehicles is twice as far as that for cars and other smaller vehicles. This increases the risk to other users of the road and the driver (or his/her passengers) of the vehicle itself.

During Operation Air Brake/Brake Safety Week the CVSA-certified inspectors conduct roadside inspections of commercial vehicles and their drivers with an emphasis on braking systems.

CVSA-certified inspectors are encouraged to meet with drivers at truck stops and other locations where drivers and mechanics congregate. The inspectors conduct inspections of commercial vehicles in an effort to instruct and educate drivers on the inspection procedure and the operation of the braking systems. This is an educational, not an enforcement event.

Educational brochures will be made available both at the roadsides and at locations (such as truck stops) where inspectors meet with drivers and mechanics. Participating jurisdictions are encouraged to use other means to educate and emphasize the importance of proper brake inspection, maintenance and safety.

Inspectors also meet with trucking company officials (such as safety directors) and truck stop operators to arrange for demonstrations of maintaining safe brakes. Members of the trucking industry are encouraged to become involved in the event, such as the state or provincial trucking associations.

CVSA provides the following information on how to keep brakes properly adjusted.

As a professional driver, you know there will be times when you really need your brakes. Having good brakes can get you out of a bad situation when another driver makes a serious driving error or some event requires extreme braking.

To be able to rely on your brakes in every driving situation, they must be properly adjusted. When your brakes aren't properly adjusted, they will let you down. Trucks that don't stop the way they should can put people's lives at risk, including your own.

Trucks and trailers that operate with brakes out of adjustment are the most common reasons that drivers and vehicle operators are charged with violations. By taking the time to properly check brake adjustment, you'll make sure your vehicle is safe and you'll also avoid being charged with a violation.

Whenever checking the brake adjustment, always be on the lookout for other defects like: damaged, broken or missing components, rusty drums and brakes that aren't working.

How can you tell whether your brakes are out of adjustment? Brake adjustment is all about pushrod stroke. There's only one way to tell when you've got a brake adjustment problem. You've got to "measure the stroke.

The parts inside a brake chamber can only stroke so far before the brake chamber "bottoms out."When that happens, the brake chamber doesn't produce any more force on the brakes.To prevent chamber "bottom out," a brake's stroke must never be longer than its "adjustment limit."

You need to measure to be sure your brakes are properly adjusted and adjustment limits are different for each size and type of brake chamber. So, you need to know the size and type of brake chambers on each vehicle you're operating as well as their adjustment limit.

You can get information about the size and type of brake chambers on a vehicle from a technician, a dealer or your employer.

The distance you can pull the brake by hand using a bar or lever is called its "slack" or "free-stroke." This distance is generally 3/8 to 3/4 inch. You may get some indication of adjustment levels, but you can't really confirm proper brake adjustment this way.

Measuring "free-stroke" or "slack" doesn't provide an accurate indication of brake adjustment.

Here's how to measure the stroke properly. Before doing anything, block the wheels, release the spring brakes and have a good look at the brakes. Each brake must be in its normal released position. Make sure nothing is obviously wrong or out of place. If your vehicle doesn't have stroke indicators, you'll have to mark each pushrod.

Now, to measure the stroke properly, you'll need to keep the spring brakes released, make sure your air pressure gauges show that you have 90 to 100 psi in the air tanks, shut the engine off and then make a full service brake application. You must have some way to hold the brake pedal down for this step.

You must measure how far each brake has stroked. Often an estimate will do, but any brake that is close to the adjustment limit must be carefully measured. Any brake that is stroking over its adjustment limit is out of adjustment.

There are devices to help you measure pushrod stroke. Visual stroke indicators can be installed onto each brake to provide a moving pointer that strokes with the brake. Some stroke indicators will help you identify exactly where the adjustment limit is and whether the stroke is under or over it. Others only provide a convenient way to measure the stroke.

Checking brake adjustment generally means you have to get under the vehicle and take measurements. Using certain types of stroke indicators makes this job much easier. You can get accurate measurements without having to crawl under the vehicle.

When your brakes are out of adjustment, what you do about it depends on whether your vehicle has manual or automatic brake adjusters.

Manual brake adjusters must be readjusted on a regular basis. If your vehicle has manual brake adjusters, you can readjust them if you've had the proper training.

Automatic brake adjusters normally don't require manual readjustment. If you have a brake that is over-stroking and it has an automatic brake adjuster, you have a problem with the brake or the adjuster. If you readjust it, you aren't really fixing the problem. The same is true if someone else only readjusts it, the problem is still there.

A manual readjustment of an automatic slack adjuster that is over-stroking is not a recommended practice.

Repeated manual adjusting will damage the brake which will no longer stay within the adjustment limit. This should be a temporary repair only.

When an automatic slack adjuster is found over stroking, proper repair of the braking wheel requires a complete diagnostic examination by an authorized brake technician in order to determine the appropriate repairs.

When you have automatic brake adjusters that are over-stroking, there are some things you need to know before you even think about readjusting them.

You may be legally prohibited from readjusting automatic brake adjusters in some jurisdictions. Your employer may also prohibit you from readjusting automatic brake adjusters.

You shouldn't readjust an automatic brake adjuster unless you have been trained on exactly how to do it. Readjusting an automatic brake adjuster improperly The brake will go out of adjustment again until the cause of the problem is repaired. It can go out of adjustment very quickly.

If the brake is over-stroking, you need to check the free stroke or slack before you decide to readjust it.

If this distance is also longer than normal, a readjustment may temporarily correct the problem.

You have to re-check the pushrod stroke and free-stroke or slack after re-adjusting the brake. The pushrod stroke must now be less than the adjustment limit and the free stroke or slack must be in its normal range. If either of these is not the case, do

not proceed. The brake is defective.

If you readjust the brake, you will have to take responsibility for doing so. This means you must continue to monitor it and report the problem at the first opportunity.

If you hire someone to correct an over-stroking problem on a brake with an automatic adjuster, be sure they know what they are doing.

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