A commercial driver is operating a vehicle equipped with air brakes on a very slippery road. They need to slow down quickly but safely. The vehicle does NOT have ABS. Which braking technique would be most appropriate?
- AStab braking: applying full brakes until the wheels lock, then releasing until they roll, and reapplying.
- BApplying steady, hard pressure to the brake pedal until stopped.
- CApplying light, continuous pressure while steering around obstacles.
- DPumping the brake pedal rapidly and continuously.
Show answer & explanationAnswer & explanation
Correct answer: A. Stab braking: applying full brakes until the wheels lock, then releasing until they roll, and reapplying.
On a very slippery road with a non-ABS air brake system, stab braking is the most effective technique for slowing down while maintaining some steering control. It involves applying the brakes fully until the wheels lock, then immediately releasing them until the wheels roll again, and reapplying. This allows for maximum braking force without prolonged skidding, which would lead to a complete loss of control.
Why the other options are wrong
- B. Steady, hard pressure on a slippery surface will quickly lock the wheels and result in a skid, losing steering control.
- C. Light, continuous pressure might not provide enough stopping power in an emergency and could still lead to a gradual skid if mismanaged.
- D. Pumping the brake pedal rapidly is generally ineffective for air brakes; it can deplete air pressure and is not recommended.
Stab Braking (Non-ABS)
A braking technique for non-ABS air brake systems on slippery surfaces, involving full brake application until wheels lock, then immediate release and reapplication.
- Used to maximize braking force while regaining steering.
- Prevents prolonged wheel lock-up and skidding.
- Only for non-ABS vehicles on slippery surfaces.
Memory trick: No ABS? Stab the brake, then release, to keep control.