Speed & Space Management

Study questions with answers

5 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. Because of brake lag, about how much extra distance does an air-brake vehicle travel at 55 mph on dry pavement compared with instantly acting brakes?

   Correct answer: About 32 feet

   Air needs about half a second or more to reach the brakes, so at 55 mph on dry roads brake lag by itself adds roughly 32 feet, pushing the total stopping distance past 450 feet.

   Source: Ohio CDL Manual — Section 5: Air Brakes

2. 2. In the same engine-off leakage test, but on a combination vehicle, what is the acceptable maximum pressure drop in one minute?

   Correct answer: Less than 3 psi

   A combination vehicle may lose slightly more air; the static leakage should stay under 3 psi in one minute, versus under 2 psi for a single vehicle.

   Source: Ohio CDL Manual — Section 5: Air Brakes

3. 3. Which statement about ABS and stopping distance is accurate?

   Correct answer: ABS does not necessarily shorten stopping distance, but it helps you stay in control

   ABS does not necessarily stop you in a shorter distance, but it helps you keep the vehicle under control and steer during hard braking.

   Source: Ohio CDL Manual — Section 5: Air Brakes

4. 4. With air brakes, total stopping distance is made up of four parts. Which set is correct?

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

   Total stopping distance for an air-brake vehicle adds perception distance, reaction distance, brake-lag distance, and braking distance together.

   Source: Ohio CDL Manual — Section 5: Air Brakes

5. 5. In a dual air brake system, if one of the two systems loses most of its pressure, what happens?

   Correct answer: Either the front or rear brakes still work, but stopping takes longer

   If one side runs very low, only the front or only the rear brakes keep working fully, so stopping takes longer. Get safely parked and have the system repaired.

   Source: Ohio CDL Manual — Section 5: Air Brakes