[This article was originally published in 2017 by Trucks, Parts, Service. It has been updated to include more timely information.]
Meritor has circulated a technical bulletin with guidance for ensuring automatic slack adjusters maintain peak performance.
According to Meritor, keeping automatic slack adjusters operating at peak performance is key to safety and regulation compliance. When verifying a Meritor stroke sensing automatic slack adjuster's operation, Meritor says technicians should always remember to check automatic slack adjuster torque to determine if replacement is needed.
The company says checking torque can be done as follows:
- Verify the snap ring is correctly secured on the camshaft
- Check slack adjuster gear torque – use a lb.-in., torque wrench and turn adjusting nut counterclockwise to rotate the gear 360 degrees, or 22 turns of the wrench, as you read the torque scale on the wrench. The value should be less than 45 lb.-in. (5 N●m) as you rotate the gear
- If the torque value is less than 45 lb.-in., (5 N●m) as you rotate the gear, the slack adjuster is operating correctly
- If the torque value exceeds 45 lb.-in., (5 N●m) as you rotate the gear, replace the slack adjuster
Also important, Meritor says to verify brake slack adjuster position (BSAP) for the type of chamber (standard or long stroke) is correctly set, and verify the use of the proper clevis for the type of chamber (standard or long stroke) and BSAP.