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TROUBLESHOOTING GUIDE
Brakes
For maintenance procedures, see "Brake System
Maintenance" on page 4-19.
PROBLEM
NO BRAKES OR BRAKES ARE
INTERMITTENT
SINGLE BRAKE DRAGGING OR
LOCKED
UNEVEN BRAKES
BRAKES APPLY TOO SLOWLY
BRAKES RELEASE TOO SLOWLY
5-4
PROBABLE CAUSE
Brake air system improperly connected
Relay/Emergency valve plugged
Defective tractor protection valve
Restricted tubing or hose line
Broken line
Tractor air system failure
Broken internal brake component
Flat spot on cam roller or cam shaft
Improper adjustment
Spider bushing or cam bracket bushing
binding
Improper lubrication
Worn brake shoe bushing
Brake drum distortion
Broken brake chamber spring
Brake chamber pushrod binding
Air brake line loose or broken
See "SINGLE BRAKE DRAGGING OR LOCKED"
Restriction in hose
Worn brake linings
Grease on linings
Broken slack adjuster
Leaking brake chamber diaphragm
Brakes need adjusting or lubrication
Low air pressure in brake system (below
105 PSI)
Restricted tubing or hose
Defective relay valve
Call Factory or see qualified Trailer/Brake Technician
Brakes need adjusting or lubrication
Brake rigging binding
Exhaust port of relay valve restricted or
plugged
Tractor pressure too low
SOLUTION
Reconnect hand valves properly.
Clean valve.
Repair or replace.
Locate and eliminate restriction.
Locate break and repair.
Troubleshoot tractor air system and repair.
Check ABS system function.
Locate and replace broken part (See
"Brake Assembly Maintenance" on
page 4-21.)
Replace and lubricate.
Adjust slack adjusters (See "Automatic
Slack Adjuster" on page 4-23.)
Lubricate or replace bushing.
Lubricate per Figure 4-1.
Replace bushing.
Replace drum.
Replace spring.
Re-align brake chamber bracket.
Tighten or repair.
Locate restriction and remove
Reline brakes.
Reline brakes.
Replace slack adjuster (See "Replacing
Slack Adjuster" on page 4-23.)
Replace diaphragm.
Adjust or lubricate as needed.
Check tractor air system.
Locate restriction and remove.
Clean or replace.
Adjust or lubricate as needed.
Align brakes or replace bent parts.
Clean valve.
Adjust to provide 105 psi min.
F-618-0911 Edition
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