Its arm is fastened to the push rod of the air brake chamber utilizing a clevis and it is mounted on to the camshaft of the foundation brake by use of a splined gear. As its name implies, it is also a device, which takes up the slack or excess clearance caused by lining and drum wear. An automatic slack adjuster (ASA) is a lever between the air brake chamber and the s-cam brake camshaft used to actuate brakes. The NTSB went on to write that “warnings in existing materials available to owners, drivers, mechanics and inspectors of air-braked vehicles equipped with automatic slack adjusters have not been successful in communicating the inherent dangers of manually adjusting automatic slack adjusters to correct out-of-adjustment brakes.”
SLACK ADJUSTER ON SEMI DRIVERS
That report, in part, reads: “The drivers and mechanics who manually adjusted the automatic slack adjusters on the trucks involved in the Glen Rock and El Cerrito accidents did not look for underlying problems with the adjusters or related foundation brake components consequently, they misdiagnosed the brake problems, probably because they were not properly educated on the function and care of automatic slack adjusters and how they relate to foundation brake systems.”
SLACK ADJUSTER ON SEMI DRIVER
NTSB ruled an ASA adjustment had led to a runaway truck accident in Pennsylvania in 2003 that claimed the life of the driver and an 11-year-old child riding in a car that the dump truck had struck during its descent on a steep downgrade.
SLACK ADJUSTER ON SEMI MANUAL
The push to end manual adjustments on ASAs is nothing new.įollowing their mandated use on tractor-trailers in 1994 and trailers in 1995, the NTSB issued a scathing report in early 2006 condemning the practice of regularly adjusting ASAs. Accident investigations by the National Transportation Safety Board (NTSB) have shown worn and improperly adjusted ASA’s to be a contributing causal factor in some accidents.”
“Overriding the automatic adjustment method can cause premature wear on the internal components and eventually result in an early end-of-life condition. “Despite being standard in the industry for almost two decades, there are still veteran technicians who will regularly put a wrench on an ASA to manually adjust it,” Accuride states in an August safety and performance report for Gunite ASAs. With out-of-service brake violations continuing to top the annual Commercial Vehicle Safety Alliance (CVSA) International Roadcheck, manually adjusting a slack adjuster can not only lead to more brake problems down the road, it can also lead to accidents. “The reasons behind adjusting an ASA outside of a brake reline should be investigated such as alignments, bushing wear, wheel conditions, etc.,” Christiansen says. “If a fleet is manually adjusting a slack adjuster regularly it can harm the longevity of the unit,” says Chris Christiansen, warranty/technical services coordinator, Accuride Corporation. Still, despite years of warnings, automatic slack adjusters (ASA) continue to be manually adjusted by technicians who may not know any better or who may be eager to get a truck out of the shop and back out on the road. They’re called automatic slack adjusters for a reason, and the manufacturers that make them want to keep it that way.
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