Air Brake Practice Test

What is the technique of stab braking primarily used for during emergency braking?

1. Push hard on the hand valve and brake pedal until stopped.

2. Push hard on the brake pedal until the wheels are locked, and let off the brakes as long as the wheels are locked.

3. Push hard on the brake pedal until the wheels are locked, then let go until the wheels begin to roll again.

4. Push lightly on the brake pedal in quick succession.

The correct answer is: Push hard on the brake pedal until the wheels are locked, then let go until the wheels begin to roll again.

The technique of stab braking during emergency braking is primarily centered on maintaining control over the vehicle while maximizing stopping power. By pushing hard on the brake pedal until the wheels lock and then releasing the brakes until the wheels start to roll again, the driver prevents the vehicle from skidding. This method allows the driver to effectively reduce speed or come to a stop without losing traction. When the wheels are locked, the vehicle slides, which can lead to a loss of control. By releasing the brake pressure as soon as the wheels lock up, the driver can regain traction and steer if necessary, since steering is only effective when the wheels have traction. The cycle of applying and releasing the brakes ensures that the vehicle can slow down efficiently while maintaining a level of control necessary to navigate or avoid obstacles in emergency situations. This makes stab braking an effective technique during emergencies, as it balances the need for braking force with the need for maintainability of steering control.