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Date of Origin – 02/24/11
Updated – 02/03/20
Air leaks at spring brake chambers, reservoir ttings, drain valves, drop hoses, and connections can cause the air
system to perform less efciently and the compressor to cycle too frequently and may eventually result in dragging
brakes.
If you suspect air system problems in either service brakes or spring brakes, don’t hesitate – service the brake
system immediately;
Trouble shooting the air brake system:
• Use the “soap bubble” test at all connections throughout the air system to detect
external leaks
• Threaded connections at the ECU
• Threaded connections at the pressure protection valve
• Any and all push-in ttings
• Check for exhaust leaks at all valves to detect internal leaks.
• Check the actuator and spring brake push rod for proper movement in operational modes.
NOTE: Never splice air brake hoses within the air brake system. This action will void part or all of the trailer
warranty.
Wheel bearings must be correctly adjusted before brake ad-
justments are made.
NOTICE:
Brake linings must not be permitted to wear to the point that
the rivets or bolts touch the drum.
NOTICE:
See the manufacturer’s maintenance manual for more information and details on brake maintenance, repair
and trouble shooting.
BRAKES
Proper maintenance of the brakes is vitally important. This includes lining inspections and brake adjustments.
A schedule for periodic adjustment, cleaning, inspection and lubrication of the brake equipment must be made
according to duty cycle and type of operation.
Brakes must be adjusted as frequently as required for correct operation and safety. The adjustment must give correct
clearance between the lining and drum, correct push rod travel, and correct balance between the brakes. Improper or
inadequate lubrication is the leading cause of dragging brakes/premature brake wear.
Brakes must be cleaned, inspected, lubricated and adjusted every time the wheel hubs are removed.
During a major overhaul, the following parts must be carefully checked and replaced with genuine replacement parts if
required.
1. Backing plates or spiders for distortion and loose bolts.
2. Anchor pins for wear and correct alignment.
3. Brake shoes for wear at anchor pins or roller slots.
4. Camshaft and camshaft bushings for wear.
5. Shoe return springs for wear and loss of strength.
6. Brake linings for grease on the lining, wear, chips, and loose rivets or bolts.
7. Drums for cracks, deep scratches, heat checking or other damage.
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