Speed & Space Management

Study questions with answers

3 sample Speed & Space Management questions with the correct answer, a short explanation, and the official handbook reference. Read through them, then take the quiz above.

1. 1. In a dual air system, if one of the two systems gets very low on pressure, what happens?

   Correct answer: Either the front or rear brakes will not fully work, so it takes longer to stop

   When one circuit loses pressure, only part of the braking remains, so stopping takes longer; stop safely and get it repaired.

   Source: Louisiana Commercial Driver's License Manual, Section 5.2 - Dual Air Brake

2. 2. What is 'brake lag' in an air brake system?

   Correct answer: The short delay for air to reach the brakes after you press the pedal

   Unlike instant hydraulic brakes, air brakes have a lag of about a half second or more while air travels through the lines to the brakes.

   Source: Louisiana Commercial Driver's License Manual, Section 5.4.4 - Stopping Distance

3. 3. Total stopping distance for an air-brake vehicle is made up of which factors?

   Correct answer: Perception, reaction, brake lag, and braking distance

   Air brakes add a brake-lag component, so total stopping distance combines perception, reaction, brake lag, and braking distances.

   Source: Louisiana Commercial Driver's License Manual, Section 5.4.4 - Stopping Distance