Emergencies & HazardsQuestion 87 of 120
Your air brakes fail on a downgrade and the low-pressure warning is on. What is your best course of action?
a.Downshift to use engine braking, look for an escape ramp or an uphill escape route, and use the parking brake or a soft-shoulder route as a last resort
b.Pump the brake pedal rapidly to rebuild pressure
c.Shift to neutral so the vehicle rolls more freely
d.Shut off the engine to stop the vehicle
Explanation
Engine braking and an escape ramp are the reliable tools once the service brakes are gone, and speed must be controlled before it becomes uncontrollable. Pumping air brakes wastes remaining pressure, neutral increases speed, and shutting off the engine removes power steering and engine braking together.
Practice all 120 questions free — no signup required.
Related questions on this topic
- You are traveling at highway speed when a front tire blows out. What should you do first?
- How can you tell that a tire has failed if you did not hear the blowout?
- Your right wheels drop off the pavement onto a soft shoulder at 55 mph. What is the correct recovery?
- Which type of fire extinguisher should you use on an electrical fire in the cab?
- A grease or fuel fire starts near the engine. Why must you never use water on it?
- You are using a fire extinguisher on a small cargo fire. What is the correct technique?
Last reviewed: · editorial process
PrepPass Editorial Team · Verified against Commercial Driver's License (CDL) General Knowledge Test · How we review