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ASVAB · Brakes and Suspension

How do disc brakes slow a vehicle?

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

By squeezing brake pads against a rotating disc (rotor) to create friction

  1. A By cooling the tires
  2. B By inflating a cushion
  3. C By squeezing brake pads against a rotating disc (rotor) to create friction
  4. D By reversing the engine

Why this is the answer

Disc brakes slow a vehicle by using a caliper to squeeze brake pads against both sides of a spinning metal disc called a rotor, which is attached to the wheel. The friction converts the vehicle's kinetic energy into heat, slowing the wheel. Hydraulic pressure from the brake fluid, created when you press the pedal, forces the caliper to clamp. Drum brakes, an older design still used on some rear wheels, press shoes outward against a drum instead. Disc brakes dissipate heat better. Understanding friction-based braking is key brake-system content.
Source: ASVAB Auto Information — Disc Brakes

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About this topic: Brakes and Suspension

Brakes and suspension questions cover disc versus drum brakes, the hydraulic principle behind the pedal, ABS, and the shocks, struts and springs that keep the tyres on the road. Expect questions on symptoms such as pulling, pulsing or bouncing. This is one of 10 Auto Information questions on brakes and suspension, each with a full explanation on a single study page.

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

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