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BRAKE PRO, LTD. TECH BULLETIN
For your information
| VOLUME 2, #10 |
COMMON AIR BRAKE COMPLAINTS
Troubleshooting the air brake system can be easy and quick if the
problems are understood and the directions for diagnosis are followed
to the letter. All problems have their roots in the basic understanding
of that system. Following is one of the most common complaints, and the
procedures for checking the problem out.
"The service brakes are not applying adequate force."
1. Improper Brake Adjustment - With the brakes applied, check the
brake chamber piston rod to see if the intersection of it and the slack
adjuster is at 90 degrees. If it is not at 90 degrees, re-adjust the slack
adjuster in accordance with its manufacturer's instructions. Always insure
that the spring parking brake chamber is fully released during this adjustment.
2. Available Air Pressure to Brake Chamber Insufficient - Check
the air brake system for an air gauge reading, is it normal? Check the
compressor for proper operation. Look for kinked or blocked air lines.
Check for defective valves.
3. Excessive Brake Lining or Drum Wear - Handle this in accordance
with the manufacturer's inspection instructions. Check for compatibility
of truck and trailer brake chambers. Check the brake chambers to insure
they are fully releasing when the brakes are not applied.
4. Improper Slack Adjuster Operation or Set Up - The angle made
by the brake actuator push rod should be perpendicular within plus or
minus three (3) degrees from zero stroke to full stroke. The brake chamber
non-pressure housing hole for the pushrod should not be elongated by the
pushrod action or show any signs of pushrod rubbing.
5. Improper Size of Brake Chambers or Excessive Load Weight - Always
consult the vehicle manufacturer's documentation to insure that the proper
brake chamber is used when doing a replacement. Always replace the chambers
in pairs, and do not mix parts manufacturers.
