A key component in any air brake system, the slack adju […]
A key component in any air brake system, the slack adjuster is responsible for the push rod stroke and for keeping the brake linings within optimal clearance between the linings and the brake drum. This is important because large trucks require a huge amount of energy to stop, so the brake slack allows for more force on the drum when the air brake system applies the brakes.
How to check for an out-of-adjustment slack adjuster
A slack adjuster that is too stiff should be manually adjusted to correct the problem. Slack adjusters that are too soft, however, may need relining or replacement.
How to check the push rod travel
The slack adjuster pushrod stroke should be no more than one inch using the brake application--applied stroke measurement method. If the pushrod stroke exceeds this measurement, it’s time to adjust the slack adjuster.
How to check the slack adjuster on S-cam brakes
A vehicle with S-cam brakes has slack adjusters that attach to each push rod. To check the slack adjusters on these brakes, park on level ground, chock the wheels and release the parking brake.
Use gloves and pull hard on each slack adjuster to see if it moves more than an inch where the push rod attaches to it. If it moves more than an inch where the slack adjuster meets the push rod, it needs to be adjusted or replaced。