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Troubleshooting
Analyzing & diagnosing trailer service
To directly assist in keeping your trailer on the road and rolling, the following troubleshooting guide has been
prepared for your convenience. You can avoid serious delay and downtime in servicing your trailer if the cause
of the trouble can be diagnosed and corrected quickly by you.
Spring parking brakes
Certain points are covered in the Trouble Shooting Chart, which apply to service brakes and spring parking
brakes. No effort is made to completely cover the entire air brake system, only the points which relate to spring
parking brakes.
(A) INSUFFICIENT SERVICE BRAKE APPLICATION WHEN SERVICE PEDAL IS DEPRESSED
1. Restricted airflow or low air pressure to service chamber.
2. Worn Brake Lining or drums worn excessively.
3. Improper adjustment on slack adjuster and chamber push rod (earn brakes).
4. Automatic adjusters not operating properly on wedge foundation brakes.
5. Improper angle for slack adjuster and service push rod (earn brakes).
6. Bent or broken earn brackets or chamber mounting brackets (earn brakes).
7. Bent or broken chamber tubes (wedge brakes).
8. Broken non-pressure halves.
9. Mounting tube loose on wedge chamber to foundation brake.
10. Improper size actuators.
11. Ruptured diaphragm.
12. Air leaks in lines, fittings or valves, and at clamp ring.
13. Wrong wedge angle (wedge brakes).
(B) INSUFFICIENT SPRING BRAKE APPLICATION
While most of the causes listed for insufficient service brake applications will
Apply here; there are a few more, which we should cover.
1. Spring brake not properly reset for full stroke.
2. Ruptured diaphragm or seal in spring brake section.
3. Broken spring.
4. Insufficient size of spring brake or proper output force.
(C) EXCESSIVE LEAKAGE· SERVICE BRAKES APPLIED
1. Leaking brake chamber diaphragm.
2. Leaking hose - tube - fittings.
3. Faulty valves
4. Clamp ring improperly installed.
(D) EXCESSIVE LEAKAGE· SPRING BRAKES RELEASED BY AIR
1. Leaking diaphragm or main seal in spring section.
2. Leaking push rod seal
3. Leaking hose - tube fittings.
(E) DRAGGING BRAKES
(Service)
1. Broken return spring in service section.
2. Service application air not exhausting properly or fast enough - clogged ports.
3. Restricted or collapsed hose or tubing
4.
Broken brake shoe retracting spring
5. Camshaft linkage binding.
(Spring Brakes)
1. Leaking diaphragm or seal in spring brake section.
2. High hold-off pressure in spring brake section.
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