Brake Slack Adjusters 6 PACK Adjustment

When our team is in the field, providing annual DOT Inspections I am surprised, but moreover concerned that some drivers are unfamiliar with a basic understanding of the brake slack adjuster system and maintaining it. Frankly, this should be a big concern considering if they encountered an Inspection station or roadside inspection checkpoint they could be PUT OUT OF SERVICE on the spot if the brakes were deemed too far out of adjustment. If this is not hitting home in regards to general safety, then what about a truck being put out of service and the lost revenue? Understanding the brake system and the required inspection and at times, an adjustment should be in a driver’s DNA.

I am not a certified mechanic, therefore I never offer any repair service as policy, but the adjustment of a brake slack adjuster is not a repair it is a standard adjustment.  Due to the fact I am not a certified mechanic, I will just be generalizing, but will provide supporting documentation, and helpful videos below as it is not a big deal to keep your brakes in adjustment.

The (ASA) Automatic Brake Adjuster system has been required for all trucks and tractors since 1994 and trailers in 1995. As you can see in the name, AUTOMATIC, so why would you need to be concerned in regards to this? Yes, the system is designed to automatically adjust the brakes as they wear. Regardless, it is still the driver’s responsibility to monitor and maintain the required pushrod brake gap and make any adjustments as needed. A common problem may occur if you are one of those drivers like myself that are easy on the brakes as you may not be applying the brakes with enough pressure to advance the adjustment AVA system mechanism forward on a regular basis. Another problem can be the worm wheel mechanism can be dry, not lubricated correctly. Please note it is vital to keep your ASA will greased for maximum performance. Drivers who are light on the brakes might consider performing what is called a “6 PACK Adjustment” procedure that can help walk the automatic slack adjusters back into adjustment, (see the videos below) to maintain the ASA system.  I would personally before manually adjusting the brakes, lube all the AVA’s, which have a grease nipple at the base. I would then perform the 6 Pack Adjustment, this should walk the system back into adjustment. To be respectful to your shop mechanic I would seek their advice how they would like you to deal with this issue when on the road to ensure you are following company protocol. The 6 PACK Adjustment can also help when you have just coupled with the trailer as this can help better sync the tractor and trailer braking system together to work more efficiently.

The ASA system is easy to check with no special tools required, and every driver is required to check and understand the required brake pushrod gap. A driver may not be required to have the skill set to adjust the brakes, but is required to check the pushrod gap and report any issues ASAP to be resolved before hitting the road. For those who may be a little vague in regards to the AVA system, please take the time to watch the below videos as well as the links to printed information to have an understanding of the importance of checking the brake pull rod gap and if you have the permission if employed to make said adjustments.

In wrapping this up, I believe that if a driver can mount snow chains, complete their required vehicle inspection, I can’t imagine any professional not being able to stay on top of this and make any adjustments or have enough common sense to let a supervisor know if in need of adjustment. It can take as little as 10 minutes to inspect and make this vital adjustment. If you can’t rely on a driver to do that maybe they should not be on our highways.

Helpful Printed Material

Air Brake Pushrod Stroke Why is it so important?

Brake stroke limits for clamp-type brake chambers

Identification of Long Stroke Brake Chambers or Brake Adjustment Limit Markings