Trucking Laws · California · November 2, 2026

California Inspectors Remind Truckers That a Single Crack in a Brake Drum Can Put a Truck Out of Service

By Big Rig Daily Staff

A cracked brake drum does not have to be large to matter. California Highway Patrol (CHP) inspectors in Redding recently shared the federal brake rule and the out-of-service criteria for cracked drums, a reminder that one crack can take a truck off the road, according to ATruckDrivers. The report is based on a CHP Redding social media post. The post did not say when an inspection took place or whether a specific truck was placed out of service.

The federal brake rule

Under Title 49 of the Code of Federal Regulations, section 393.47(a), brake components "must be constructed, installed and maintained to prevent excessive fading and grabbing." The rule adds that "the means of attachment and physical characteristics must provide for safe and reliable stopping of the commercial motor vehicle."

The out-of-service standard

Inspectors also use out-of-service criteria from the Commercial Vehicle Safety Alliance (CVSA). Under those criteria, a vehicle can be placed out of service if "any portion of the drum has any external crack or has any crack that opens upon brake application."

That second part is easy to miss. A drum can look sound while a truck is parked, but a crack that opens only when the brakes are applied still counts under the criteria quoted in the report.

What out of service means

A truck placed out of service is not allowed to continue until the problem is fixed. The CHP post, as described in the report, was meant as a reminder of the standard and did not announce a new rule.

A pre-trip habit

Brake drums are one item on a walk-around check. Big Rig Daily's pre-trip inspection checklist covers a full walk-around, and a report on a semi stopped in Iowa with overheated brake drums after a motorist's tip shows how brake problems can show up on the road. A report on Kenworth making its electronic parking brake standard covers a different part of the brake system.

Quick facts

• Who: CHP inspectors in Redding, California.
• Federal rule: 49 CFR 393.47(a), brake components must provide safe and reliable stopping.
• Out-of-service criteria: any external crack, or any crack that opens upon brake application.
• Not stated in the report: when the post was made or whether a truck was placed out of service.

FAQ

Does any crack in a brake drum count?

Under the criteria quoted in the report, a vehicle can be placed out of service if any portion of the drum has any external crack or any crack that opens upon brake application.

Is the brake drum crack out-of-service standard a new rule?

No. The CHP post shared existing federal and CVSA standards as a reminder.

Was a truck placed out of service in the CHP Redding brake drum reminder?

The report does not say.

A question for readers

Truck drivers, how closely do you check your brake drums on a pre-trip, and has a cracked one ever put you out of service?

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