By John Smith
The warning labels that are printed next to an automatic slack adjuster’s (ASA) maintenance guidelines are about as subtle as the Surgeon General’s declarations on a pack of cigarettes. They may not say that brake adjustments will cause cancer, but they certainly leave no question that a readjustment could mask a number of issues with foundation brake components.
Despite the maintenance-related considerations that remain – an ASA should not be considered “maintenance-free” – it is difficult to ignore the improvements that have emerged since ASAs became mandatory equipment in the mid-1990s.
“We are enormously better off than we were with manual slack adjusters,” observes Mark Kromer, engineering manager for the specialty products group at Bendix Commercial Vehicle Systems.
His co-worker, service engineer John Hawker, sees proof of the improvements in roadside inspection statistics. A decade ago, out-of-adjustment brakes accounted for 72.3 percent of all out-of-service instances, but the numbers have been dropping at a rate of 4.8 percent a year, he says.
Today’s brakes account for 52.6 percent of out-of-service figures, and that is when you include maintenance issues such as defective ABS warning lamps.
Several design improvements also have emerged in the ASAs themselves.
