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 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. Back off the bolt one quarter to 1/2 a turn to restore the clearance.They’re called automatic slack adjusters for a reason, and the manufacturers that make them want to keep it that way. If you detect outward movement, you’re turning the bolt the wrong way.Ģ. Watch the chamber push rod and slack adjuster arm. If you are turning the bolt the right way, the cam will turn in the same direction as it does when you apply the brakes. Some adjusting bolts turn clockwise and some turn counter-clockwise. Turn the adjusting bolt until you feel solid resistance. But under moderate to heavy braking, you could find yourself in a runaway truck. It shall be noted that when one brakes lightly, even poorly adjusted brakes seem to work. This is the most important inch of your life. Why do we need it and why poor brake adjustment can lead to even death?īelieve it or not but most common cause of brake failure is poor brake adjustment. So when a slack reaches 1 inch (2.54 cm), the brakes must be adjusted. If it does then slack adjuster is not fitted properly. * Observe and see if it moves more than one inch. * Then turn off the parking brakes and pull very hard on each slack adjuster. * Park on a ground that is properly levelled. To check if it is fitted as it should be, follow these steps: How can you check if the Slack Adjuster is fitted properly? You can also call it an adjusting nut that is present on the back side of the brake drum and is used for brake adjustment. The Slack Adjuster Wiki What is a Slack Adjuster?Ī Slack Adjuster is designed for use in S-Cam brakes which is mostly used in trailer and trucks, that is commercial vehicles.
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