Brake systems diagnostic guide – Bendix Commercial Vehicle Systems BRAKE SYSTEM TROUBLESHOOTING GUIDE User Manual
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15
BRAKE SYSTEMS DIAGNOSTIC GUIDE
POTENTIAL CONDITION/CAUSE
ACTION (SERVICE MANUAL SECTION)
Contamination -
—No air dryer
Install air dryer
—Faulty air dryer
Repair or replace
—Dirty or damaged filter
Replace filter
—Desiccant debris
Clean desiccant
—Incompatible oils
Drain and refill with proper oil
—Leaking air tanks
Repair or replace tank
—Mis-adjusted brakes
Readjust brakes
Insufficient pushrod free travel:
• Pushrod length too long
Shorten pushrod to proper length
• Incorrect installation of slack adjuster
Perform correct installation procedure (6)
Overadjusted slack adjuster:
• Incorrect in-service adjustment (manual)
Readjust using proper procedure
• Incorrect setup of external reference control arms
Perform correct setup procedure
(Eaton-Haldex)
• Incorrect slack window (auto slacks)
Replace with proper slack window (6)
• Contamination of internal parts (auto)
Replace slack adjuster (6)
• False feedback to slack adjuster (review all
Check lining clearances and hub/drum run-out (4)
foundation brake and wheel end problems)
• Auto slack installed and/or adjusted with spring
Readjust with spring brake fully retracted
brake partially applied (low reservoir pressure)
• Performing downgrade braking using light drag
Use snub method on downgrades
Cam flip over:
• Worn linings/drums
Replace linings/drums (3,5,6)
• Worn shoes/rollers
Replace as necessary (3,6)
• Worn cam
Replace cam (3,6)
Binding of camshaft in bushings:
• Corrosion
Replace bushings and lubricate (5)
• Lack of lubricant
Lubricate with proper lubricant (2)
• Damaged bushings/journals
Replace bushings/journals (5)
Drum out-of-round:
• Worn-out drum
Replace drum (3,6)
• Overloading of vehicle
Don’t exceed legal weight rating of vehicle
• Over-aggressive linings
Change lining friction rating
• Driver abuse
Correct as required
• Incorrect turning of drum
Perform correct drum turning operation (2)
• Performing downgrade braking using light drag
Use snub method on downgrades
P
ARKING BRAKE WILL NOT HOLD/
DRAGGING BRAKES