Speed & Space Management

Study questions with answers

6 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. You notice you must apply more and more pressure to hold the same speed. What does that usually mean, and what should you do?

   Correct answer: The brakes are fading, so slow down and drop to a lower gear

   Needing extra application pressure to maintain speed is a sign of fading brakes; reduce speed and shift to a lower gear.

   Source: Massachusetts CDL Manual — Section 5.1.10: Application Pressure Gauge

2. 2. On an air-brake vehicle, what is "brake lag"?

   Correct answer: The short delay before the air reaches and works the brakes after you press the pedal

   Unlike instant hydraulic brakes, air brakes take about half a second or more for the air to travel and act; that delay is brake lag.

   Source: Massachusetts CDL Manual — Section 5.4.4: Stopping Distance

3. 3. What most directly causes brake fade on a long downgrade?

   Correct answer: Excess heat from overusing the service brakes instead of relying on engine braking

   Riding the service brakes builds heat that changes the linings and expands the drums, cutting braking force; that loss is brake fade.

   Source: Massachusetts CDL Manual — Section 5.4.5: Brake Fading or Failure

4. 4. Using the recommended braking technique on a long, steep downgrade, when do you release the brakes after a snub?

   Correct answer: After your speed has dropped to about 5 mph below your safe speed

   Once in a low gear, brake firmly until you are about 5 mph below your safe speed, then release; repeat when you climb back to the safe speed.

   Source: Massachusetts CDL Manual — Section 5.4.6: Proper Braking Technique

5. 5. For an average driver on dry pavement in good conditions, the total stopping distance of an air-brake vehicle at 55 mph is roughly how far?

   Correct answer: More than 450 feet

   Adding perception, reaction, brake lag, and braking distances, an air-brake vehicle at 55 mph needs over 450 feet to stop.

   Source: Massachusetts CDL Manual — Section 5.4.4: Stopping Distance

6. 6. The total stopping distance for an air-brake vehicle is made up of four parts. Which list is correct?

   Correct answer: Perception, reaction, brake-lag, and braking distances

   Air-brake stopping distance combines perception, reaction, brake lag, and braking; brake lag is the extra factor compared with hydraulic brakes.

   Source: Massachusetts CDL Manual — Section 5.4.4: Stopping Distance