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CDL · Brake Fade and Downgrades

What is 'brake fade' and what causes it?

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

Loss of braking power caused by overheating the brakes (often from continuous/excessive use on long downgrades)

  1. A Brakes changing color
  2. B Brakes that work better when hot
  3. C A type of brake fluid
  4. D Loss of braking power caused by overheating the brakes (often from continuous/excessive use on long downgrades)

Why this is the answer

BRAKE FADE is the LOSS of braking power caused by OVERHEATING the brakes — typically from continuous or excessive brake use, especially on long, steep DOWNGRADES. CDL air brakes. As brakes overheat, they lose their ability to create friction, so they become less effective (or fail).

Prevention: use a low gear and engine braking on downgrades; use the 'snub' braking method (firm application to slow down, then release to let brakes cool); don't ride the brakes continuously; choose a safe speed for the grade. Excessive brake fade can cause runaway trucks. Knowing brake fade (overheating from overuse, especially downhill) and how to prevent it is commonly tested.

Source: FMCSA CDL Manual — Air Brakes, Brake Fade

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About this topic: Brake Fade and Downgrades

Brake fade is the loss of braking power that happens when drums or discs get too hot to convert motion into heat efficiently — the pedal still moves, but the truck stops slowing. On the CDL air brakes test it shows up in questions about long downgrades, riding the brakes, snubbing (controlled braking) and why a lower gear, not the service brakes, is your primary speed control on a hill. This is one of 5 Air Brakes questions on brake fade and downgrades, 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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