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CDL · Vehicle Inspection

Which of the following is the correct procedure for testing the parking brake before driving?

Reviewed by Jordan Morley, Editorial Lead at 247SimpleTests. Written by the 247SimpleTests Editorial Team from the official source material cited on every question.

Correct answer

With the parking brake set, place the vehicle in a low gear and gently release the clutch — the vehicle should not move

  1. A With the parking brake set, place the vehicle in a low gear and gently release the clutch — the vehicle should not move
  2. B Allow the vehicle to roll on a flat surface to confirm the brake holds
  3. C Push hard on the brake pedal three times to test air pressure
  4. D With the engine off, set the parking brake and try to start the engine in gear

Why this is the answer

Test the parking brake by setting it, placing the vehicle in a low gear, releasing the clutch slowly with the engine running, and gently increasing power. The parking brake should hold the vehicle in place; if the truck rolls or creeps, the parking brake is defective and the vehicle must not be driven. This test must be done in a safe location away from anything you might roll into. Letting a vehicle roll on a flat surface only verifies that the brake holds against gravity, not against engine torque. Starting the engine in gear is dangerous and not a test procedure. The parking brake (which is spring-applied and air-released on a heavy commercial vehicle) is independent of the service brakes and must be tested separately each day.
Source: FMCSA CDL Manual 2.1.10 Parking Brake Check

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About this topic: Vehicle Inspection

The pre-trip inspection catches defects before they become crashes. CDL examiners will fail you if you skip steps or miss a deliberate fault, and federal regulations require an inspection at the start of every duty day. This is one of 9 General Knowledge questions on vehicle inspection, each with a full explanation on a single study page.

New to this exam? Our CDL exam guide explains the format, scoring, and how to prepare.

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