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Home Under The Hood What is the proper way to check and adjust cam brakes?

What is the proper way to check and adjust cam brakes?

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Maintaining properly adjusted brakes is not only a matter of compliance but also a fundamental aspect of ensuring vehicle safety. In the heavy-duty industry, the slack adjuster plays a critical role in regulating brake performance. In this guide, we explore the best method for checking and adjusting slack adjusters to guarantee optimal brake function. By understanding the steps involved, drivers and maintenance personnel can take proactive measures to uphold the highest safety standards on the road.

The best method of checking is to manually pull or pry each slack adjuster and measure the pushrod travel. If you can pull a pushrod out one inch or more, that brake should be readjusted.

If you are already under the vehicle, it only takes a short time longer to adjust the brakes than it takes to check them. Then you are sure that your brakes are in perfect adjustment. Good enough is just not good enough.

An outward movement of the chamber pushrod and slack adjuster as you turn the adjusting bolt indicates that you are turning in the wrong direction.

Once the proper adjusting direction is found, continue turning the adjusting bolt until solid resistance is met. This indicates that the brake shoes have contacted the drum.

To restore running clearance so that the brakes do not drag, back off the adjusting bolt approximately one third turn. Usually that is sufficient, but you can again manually pull or pry the slack adjuster and measure the pushrod travel. Pushrod travel or "slack” as it is frequently called, should be approximately 1/2 inch.

Finally, be sure that the locking device has re-engaged the head of the adjusting bolt, so that road vibrations will not cause the adjuster to back off.

IMPORTANT 

Most brakes "set up" with a normal clockwise turn of the adjusting bolt, but some require a counterclockwise turn.

In the world of heavy-duty vehicle maintenance, the mantra "good enough is just not good enough" holds true, especially when it comes to brake adjustments. The simplicity of manually checking and adjusting slack adjusters, as outlined in this guide, is a small investment of time that pays significant dividends in safety and performance. Whether under the vehicle for inspection or making adjustments, the extra effort expended ensures that brakes are not just functional but meticulously fine-tuned. Remembering the importance of correct adjusting directions and confirming the engagement of the locking device adds an extra layer of diligence, creating a comprehensive approach to brake maintenance that prioritizes safety on every journey.