Brake adjustment violations

May 12, 2017 0 Comments in Uncategorized by


Reminder of the week.

Brake adjustment violations

With automatic slack adjusters on almost all commercial motor vehicles today, a portion of these violations can be attributed to the technical working of the automatic slack adjuster.

Professional drivers 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 six 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 automatic brake adjustment. To ensure that the brakes are always in adjustment, we recommend the following:

  1. During your pre-trip inspection, complete 10 full brake applications while the unit is parked. A slack adjuster will adjust approximately ½ inch with every 10 full brake applications. By including this procedure as part of your pre-trip inspection, it will ensure that your brakes are always in adjustment. In the event of a roadside inspection, repeat this process prior to the inspection process. This will ensure that the automatic slack adjuster have the adjusted the brakes to compliance
  2. During the Pre-Trip inspection, a driver is required by DOT to check the low air pressure-warning device. This should be audible at 60 psi. To check this device the air pressure must be lowered to 60 psi. If while accomplishing this portion of the inspection, a driver would fully apply and release, the air pressure should drop approximately 4 psi with each application.


Klemens Kuqi 

Compliance Manager