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Common Brake Out-of-Service Issues — and how to catch them first.
Brake defects account for the largest share of out-of-service violations at CVSA inspections in Ontario. Nearly all are preventable with regular measurement and maintenance.
Brake stroke / pushrod travel
- Standard stroke limit: typically 1.75 inches (type 20/24) or 2 inches (type 30)
- Measured with the brakes applied at 80-100 PSI
- Automatic slack adjusters still fail: they compensate for lining wear but can't fix a worn chamber
- Measure, don't guess: visual inspection is not sufficient for CVSA compliance
Lining and drum condition
- Minimum lining thickness varies by chamber size (typically 1/4 inch minimum)
- Drums must be within maximum diameter stamp and free of cracks, heat checks
- Oil or grease contamination on lining requires replacement, not cleaning
- Mismatched lining materials on the same axle reduce braking efficiency
Air system defects
- Air leaks exceeding 4 psi/minute (single) or 6 psi/minute (combination)
- Compressor not building to governor cut-out pressure (typically 120-125 PSI)
- Faulty or missing air dryer allowing moisture into the system
- Spring brake chambers that don't release or apply properly
- Treadle valve (foot valve) not returning to zero pressure
ABS / EBS defects
- ABS warning lamp not illuminating during bulb check at startup
- ABS warning lamp staying on while driving (active fault code)
- Open or shorted wheel-speed sensor circuits
- Modulator valve failure (won't release or apply)
- Mismatched or incorrect ECU software calibration
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Questions?
Need help with your fleet compliance?
Call our service desk or send a request. We're happy to talk through any of these topics.