CLP Basic Vehicle Control 3 — Questions and Answers
Question 1: What should you do if your commercial vehicle's brakes begin to fade on a long downhill grade?
- Apply the brakes harder to compensate for the fade
- Use the trailer brake hand valve only
- Downshift immediately and look for an escape ramp (Correct answer)
- Turn on hazard lights and maintain current speed
Correct answer: Downshift immediately and look for an escape ramp
Brake fade signals overheated brakes; downshifting increases engine braking and escape ramps provide a last resort to stop safely.
Question 2: Which of the following best describes 'stab braking' for commercial vehicles without ABS?
- Applying full brake pressure and releasing when wheels lock, then reapplying (Correct answer)
- Gently pumping the brakes in short rapid intervals
- Applying one-third braking force to avoid lockup
- Pressing the brake pedal to the floor and holding it
Correct answer: Applying full brake pressure and releasing when wheels lock, then reapplying
Stab braking involves applying full pressure until wheels lock, releasing briefly to let them roll, then reapplying, repeating as needed.
Question 3: When should you downshift a manual transmission commercial vehicle?
- Only after reaching the bottom of a hill
- Before entering a curve or grade, not while in it (Correct answer)
- Whenever the engine reaches maximum RPM
- While braking to make the stop shorter
Correct answer: Before entering a curve or grade, not while in it
Downshift before curves and hills so you can focus on steering and speed control rather than shifting during the maneuver.
Question 4: What is the correct procedure for turning around in a commercial vehicle when space is limited?
- Make a three-point turn using forward and reverse movements
- Use a U-turn in a single movement if the road is wide enough
- Drive around the block to avoid reversing (Correct answer)
- Use only the trailer brake to pivot the vehicle
Correct answer: Drive around the block to avoid reversing
CDL training recommends going around the block rather than attempting a three-point turn, since reversing a large vehicle in tight areas is dangerous.
Question 5: How does cargo weight affect the braking distance of a commercial vehicle?
- Heavier loads always shorten braking distance due to added traction
- Braking distance is unaffected by cargo weight if brakes are properly adjusted
- Heavier loads increase braking distance because more inertia must be overcome (Correct answer)
- Lighter loads increase braking distance because tires have less grip
Correct answer: Heavier loads increase braking distance because more inertia must be overcome
Greater vehicle mass requires more braking force and distance to stop because inertia increases with weight.
Question 6: What is the purpose of a runaway truck ramp (escape ramp)?
- To allow trucks to bypass weigh stations legally
- To provide an emergency stopping area for vehicles with brake failure on steep grades (Correct answer)
- To separate truck traffic from passenger vehicles on mountain passes
- To allow trucks to park temporarily without blocking traffic
Correct answer: To provide an emergency stopping area for vehicles with brake failure on steep grades
Escape ramps use deep gravel or an uphill grade to stop a truck that has lost braking ability on a steep downhill.
Question 7: In a commercial vehicle with air brakes, what happens when you push the brake pedal down?
- Hydraulic fluid is compressed and sent to the brake chambers
- Air is released from the system to reduce pressure on the brakes
- Air pressure is directed to the brake chambers to apply the brakes (Correct answer)
- The parking brake engages automatically to assist stopping
Correct answer: Air pressure is directed to the brake chambers to apply the brakes
Pressing the pedal opens valves that send compressed air to the brake chambers, which push brake shoes or pads against drums or rotors.
CLP Basic Vehicle Control 3
What should you do if your commercial vehicle's brakes begin to fade on a long downhill grade?