Practice question

For the Washington CDL Air Brakes knowledge test, what does the S-cam do in an S-cam drum brake?

  1. It releases air from the lines
  2. It rotates between the brake shoes, forcing them outward against the drum
  3. It cools the brake drum
  4. It activates the low-pressure warning

Answer: B — It rotates between the brake shoes, forcing them outward against the drum

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