Automatic slack adjusters are designed to continuously and automatically maintain the brakes in proper adjustment during normal use. However, they must be checked daily to ensure they are maintaining proper push rod travel - less than one in. (25.4 mm) when manually pulled and less than two in. (50.8 mm) when the brake is applied. Normally two to four brake applications of 100 psi (689 kPa) per day will keep the brakes properly adjusted. If they are badly out of adjustment it may take up to 12 brake applications of 100 psi to adjust them. If they are still out of adjustment a qualified person should repair them. Do not try to adjust them yourself unless you have been trained by a mechanic or trainer who is familiar with setting up and backing off this type of automatic slack adjuster.
Automatic slack adjusters must be checked daily.