§393.41 requires every CMV to be equipped with a parking-brake system that can hold the vehicle stationary on any grade on which it is normally operated, under any condition of loading. For air-braked vehicles the parking system is the spring-applied portion of the foundation brake; for hydraulic-braked vehicles the parking system is mechanical, typically a driveline or rear-wheel applicator.
Severity weight + OOS
Severity weight 4 in the Vehicle Maintenance BASIC. A parking brake that does not hold on grade is an out-of-service condition — the inspector tests by setting the brake and applying tractor effort or rolling the vehicle on a grade, and movement is the cite.
How it gets cited
Three patterns: (1) air-brake parking system that loses pressure overnight — the spring brakes apply correctly but air leaks back in and releases them; (2) hydraulic driveline parking brake with worn shoes or a maladjusted cable; (3) parking brake that holds on flat ground but releases on the inspector's grade test.
How to prevent it
- Test the parking brake on every pre-trip — set the brake, attempt to move under low throttle, confirm the vehicle does not roll.
- Annual inspection §396.17 must include a parking-brake hold test, not just a visual.
- Investigate any air-system leak that develops between trips — a slow leak that affects service braking will affect the parking brake first.
How Roadworthy HQ helps
A parking-brake 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.