The brake experts at ArvinMeritor offer tips to help truck maintenance professionals get the brake performance they expect.
1. Automatic Slack Adjusters: Always troubleshoot brakes when the air chamber stroke exceeds the allowable limits. When you need to replace one automatic slack adjuster, replace all the ASAs on the same axle with components that meet the original spec'. Mismatched brands can result in uneven brake wear, unbalanced braking and poor brake performance. Excessive push rod stroke may be an indication that a problem exists with the foundation brake, automatic slack adjuster, brake actuator or other system components. Confirm correct brake operation before returning the vehicle to service.
2. Cam Brakes: Replace all the springs, anchor pins, bushings and rollers. This includes replacing the cam brake return springs each time cam brakes are relined. Inspect the entire brake structure for wear, cracks or other damage. Replace damaged parts with new rather than welding or repairing. Lubricate the cam brake assembly as required.
3. Valves: New valves in your air brake system should have the same crack pressure as those you’re replacing. Replacing a valve with one that has a higher or lower crack pressure than the original valve can result in an unbalanced brake system and unacceptable lining and drum life.
4. Replacement Linings: Replace the linings on all four brakes of a tandem axle or at minimum both brakes of a single axle at the same time. Not replacing a unit’s brake linings at the same time may contribute to brake balance problems, uneven wear, reduced lining life, maintenance problems or drum-cracking.
5. Drums: There are two basic brake drum types: cast and composite. They differ in their abilities to absorb and dissipate heat. Using different weight, sizes or types of drums on the same axle could result in unbalanced braking and improper functioning of the automatic slack adjuster. The result will be poor brake performance due to uneven lining and drum wear.
6. Cam Heads: Cam heads vary from one manufacturer to another. Some are engineered to provide constant lift while others promise constant torque. As with any brake component, use the proper replacement cam. Failure to do so can result in an unbalanced brake system and unacceptable lining and drum life.
7. Cam Rollers: Are they properly lubricated? The way to lubricate a cam roller is directly in the web roller pocket and not at the c...