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Dual Air Brake Systems

Dual Air Brake Systems is a required knowledge area under 49 CFR 383.111(b)(1) and (b)(4). The minimum pressure build-up requirement tested here is directly codified at FMVSS No. 121, S5.1.1.

Practice Dual Air Brake Systems

5 Questions

  1. Structurally, how is a dual air brake system actually built?
  2. In a vehicle with a dual air brake system, which tank's pressure determines when the low air pressure warning activates?
  3. If one of the two systems in a dual air brake system loses most of its pressure while the vehicle is being driven, what happens?
  4. Why do most heavy-duty vehicles use a dual air brake system instead of a single air system?
  5. In a dual air brake system, how can a driver tell which of the two systems, the primary or the secondary, has lost pressure?