Practice question

What is the primary purpose of an engine brake (commonly known as a Jacob's or Jake brake) on heavy diesel vehicles?

  1. To increase fuel efficiency during acceleration
  2. To slow the vehicle using engine compression, reducing wear and heat on the service brakes during long descents
  3. To cool the engine cabin during hot weather
  4. To lock the drive wheels during parking

Answer: B — To slow the vehicle using engine compression, reducing wear and heat on the service brakes during long descents

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