CDL Combination Vehicles TestDriving Combination Vehicles SafelyEasy
A commercial driver is operating a combination vehicle on a level road and observes a pedestrian unexpectedly enter the roadway ahead. What is the most effective braking technique to use to maintain control and stop safely?
- ADownshift aggressively and use the engine brake primarily.
- BApply the trailer hand brake firmly to slow down the trailer first.
- CPump the brake pedal rapidly to prevent wheel lock-up.
- DApply steady, firm pressure to the service brake pedal without locking the wheels.
Show answer & explanationAnswer & explanation
Correct answer: D. Apply steady, firm pressure to the service brake pedal without locking the wheels.
Applying steady, firm pressure to the service brake pedal without locking the wheels is the most effective technique for emergency braking in a combination vehicle, as it maximizes braking force while maintaining steering control. Locking the wheels can lead to skidding and loss of control.
Why the other options are wrong
- A. While downshifting and engine braking are important for slowing down, they are not sufficient for an emergency stop and should be used in conjunction with, not instead of, the service brakes.
- B. Applying the trailer hand brake firmly can cause the trailer wheels to lock up, leading to a jackknife.
- C. Pumping the brakes is generally not recommended for vehicles with ABS, and even without ABS, steady pressure is often more effective than pumping.
Emergency Braking Technique
The most effective method for stopping a combination vehicle quickly and safely in an emergency, maximizing braking force without losing control.
- Apply firm, steady pressure to the service brake pedal.
- Avoid locking the wheels to maintain steering control.
- Release and reapply brakes if wheels begin to lock (if not equipped with ABS).
Memory trick: STOP! Smooth, Steady, Safe