SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/cdl-no-parking-brake-hot

When should you NOT set the parking brakes?

When the brakes are very hot.

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  1. When the brakes are very hot ✔
  2. When parked on a hill
  3. When parked overnight

Why: Hot brakes, like after a steep grade, can be damaged by the parking brakes. Chock the wheels on a level surface and let the brakes cool first.

Huh, didn't know that: Also skip them when the brakes are very wet in freezing weather, or they can freeze.

The dad joke
Why did the brakes go on vacation? They needed to cool down.
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References

Answer: When the brakes are very hot. Hot brakes, like after a steep grade, can be damaged by the parking brakes. Chock the wheels on a level surface and let the brakes cool first.

  1. California Commercial Driver Handbook (DMV) www.dmv.ca.gov/portal/file/california-commercial-driver-handbook-pdf
    Do not use the parking brakes if the brakes are very hot (from just having come down a steep grade)
    Checked 2026-10-10.

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