A brake out of adjustment is the highest frequency violation during a roadside inspection!

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Professional drivers typically will maintain a space cushion between them and the vehicles in front of them. When applying the brakes they will usually apply the brakes with 15% to 25% air application. Only in a defensive action will a driver apply the brakes with greater than 60% air application. These braking incidents are referred to as “Panic Stops” or “Rapid De-acceleration Occurrences.” Analysis reflects that most professional drivers will require less than 6 of this type of brake application per 1,000 miles driven.

Most International trucks are equipped with a “Stroke Sensitive” automatic adjuster. This type of slack adjuster adjusts the brakes on the return stroke.

This adjustment occurs only when the application is greater than 60%. The better the driver, the less opportunity there is for the automatic slack adjuster to make a brake adjustment. To ensure that the brakes are always in adjustment, we recommend the following:

An automatic slack adjuster will adjust approximately ½ inch with every 10 full brake applications.

Including this procedure as part of your pre-trip inspection will ensure that your brakes are always fully in adjustment. In the event of a roadside inspection, repeat this process while waiting your turn in line for the inspection process. This will insure that you are not red-tagged, due to a slack adjuster “Out-of-Service” condition or receive a violation. After completing this procedure and the brakes are still not adjusted or are inspected and found to be out-of-service, then it indicates there is a problem with the adjuster, with the adjuster’s installation or with related foundation brake components.

AS A DRIVER, DO NOT TRY TO MANUALLY ADJUST AN AUTOMATIC SLACK!!

The following is the Air Brake Inspection Procedure that will be used by the CVSA inspectors during Brake Safety Week:

Inspection Items:

  • Driver License
  • Registration
  • Low Air Warning Device
  • Pushrod Travel (Adjustment)
  • Brake Linings/Drums
  • Air Loss Rate (If leak detected)
  • Tractor Protection System


Operation Air Brake Inspection Procedure:

Step 1: Choose the Inspection Site

Step 2: Safety Considerations

Step 3: Check Air Brake Mechanical Components

Step 4: Check Steering Axle Air Brake Mechanical Components

Step 5: Check Brake Adjustment

Step 6: Build the Air Pressure to 90 - 100 PSI

Step 7: Check the Air Brake ABS System (If Applicable)

Step 8: Test Air Loss Rate

Step 9: Test Low Air Pressure Warning Device

Step 10: Check the Tractor Protection System

Step 11: Finalize paperwork, and provide the results to the driver (i.e. out-of-service, etc.)