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CDL · Air Brake Parts

What is the function of the brake chambers in an air brake system?

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

To convert air pressure into the mechanical force that applies the brakes at each wheel

  1. A To inflate the tires
  2. B To convert air pressure into the mechanical force that applies the brakes at each wheel
  3. C To cool the engine
  4. D To store fuel

Why this is the answer

BRAKE CHAMBERS convert AIR PRESSURE into the MECHANICAL FORCE that applies the brakes at each wheel. CDL air brakes. When the driver presses the brake pedal, air pressure enters the brake chamber, pushing a diaphragm and pushrod, which moves the SLACK ADJUSTER and turns the cam (or wedge) to press the brake shoes against the drum (or pads against the rotor). The brake chamber is where air pressure becomes braking force. SLACK ADJUSTERS must be properly adjusted (out-of-adjustment brakes are a common violation and safety hazard). Knowing the brake chamber converts air pressure to mechanical braking force is commonly tested.
Source: FMCSA CDL Manual — Air Brakes, Brake Chambers

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About this topic: Air Brake Parts

Knowing the parts of the air brake system — compressor, governor, supply tank, dryer, slack adjusters, spring brakes — is required so you can recognize defects during inspection. This is one of 22 Air Brakes questions on air brake parts, 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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