§393.52 sets the service-brake performance specifications: the vehicle must be capable of developing a braking force at least equal to the percentage of GVW set out in §393.52(b), and the service brake must stop the vehicle within the distance specified for the vehicle type and speed. Parking-brake performance is also specified — the vehicle must hold on the grade given in §393.52(d).
OOS
Performance failure measured by an inspector (commonly via a performance-based brake tester or a measured slow-down test) is an OOS condition. The vehicle may not continue from the inspection until performance is restored.
Severity weight
Severity weight 7 in the Vehicle Maintenance BASIC. The weight reflects how close a §393.52 failure is to a crash; this is the rule that catches the brakes that "kind of work" but cannot stop the vehicle.
How to prevent it
- Pair §393.47 adjustment checks with §393.52 performance tests; a vehicle within adjustment can still fail performance if linings are glazed or contaminated.
- Performance-based brake testers (PBBT) at the carrier's yard catch what stroke checks miss.
- Replace all brake hardware on an axle together — mixed hardware ages unevenly and degrades performance.
How Roadworthy HQ helps
A brake-performance citation shows up in Roadworthy HQ as part of the inspection it came from, not as a record of its own: the app does not store individual violation codes. Log the roadside inspection on the vehicle's Inspections tab: date, state, level, driver, the number of violations, and whether it was out-of-service. For an out-of-service inspection the 15-day §396.9(d)(3) repair-certification countdown stays on that tab until you enter the certification date. The rule's 15 days cover every violation on the report, not only out-of-service ones, so for a non-OOS inspection that date is yours to track. The repair itself goes in the vehicle's maintenance log: date, type, what was done, who did it, and cost. DVIRs are logged per vehicle with the defect described in your own words, and a defect marked safety-affecting that is logged without a repair certification sends a critical alert. The §396.17 annual inspection report uploads to the vehicle, with reminders 60, 30, and 7 days before the next one is due.