New Jersey Air Brakes Practice Test

In a dual air brake system, what does low pressure in one system indicate?

1. Brakes will be more aggressive

2. Both front and rear brakes will not function

3. Only the front or rear brakes may not be fully functional

4. Brakes will only operate manually

The correct answer is: Only the front or rear brakes may not be fully functional

In a dual air brake system, low pressure in one of the systems typically indicates that only the front or rear brakes may not be fully functional. This is because a dual air brake system is designed with two independent braking circuits. If one circuit experiences low pressure, it does not affect the other circuit completely, allowing the vehicle to retain some braking ability. Essentially, the vehicle may still be able to stop using the functioning circuit while the other circuit may require attention. This design is a safety feature aimed at preventing complete brake failure, allowing a driver to maintain some control even if one part of the system is compromised. For clarity, while aggressive brakes would generally require adequate air pressure to ensure full function, low pressure does not enhance braking capability. Both front and rear brakes becoming entirely ineffective indicates a more severe condition, which would not occur solely from low pressure in one system. Additionally, while manual brake operation is a possibility, it does not specifically relate to the situation of low pressure in one part of a dual system; the primary design is focused on maintaining functionality through the independent circuits.