Air brake systems are made up of many separate parts, all of which must be in good condition to provide reliable operation. Inspections catch problems early. In addition to visual driver inspections, technician inspections are important and should be performed on a regular basis," says Joe Kay, chief engineer of brake systems, Meritor. "During these more thorough inspections, technicians should check linings for wear, cracks and fractures."

Check air break systems for:

• Check for valve failure in primary or secondary circuit. These failures can compromise the system. To check, open the drain valve on the wet tank. 
• Look for accelerated wear. Check for dirt and debris between the lining and braking surface as well as on rubber boots and seals.
• Fractures and leaks.
• Proper operation of the push rods and slack adjusters. This is essential to maintain the position of the brake shoes relative to the drum.
• Check push rod actuation out of the brake chambers. Look for broken or weak springs.
• Check slack adjusters for broken or missing parts.
• Inspect brake lining for cracked, broken lining blocks, uneven wear on an axle, and make sure there is no scoring and the drums are not out of round.
• Don't forget to check the parking brake daily for leaks in each chamber or broken or damaged components.

If the air brake system needs repair, choose the repair parts wisely.

• Consider differences in the friction materials
• Make sure performance meets or exceeds the OEM brake linings