Examkin

Question

Difficulty: MediumBrake Failure

While traveling on a level expressway, a driver presses the brake pedal on a hydraulic brake-equipped vehicle and feels it sink straight to the floor without slowing the truck. After quickly pumping the pedal several times with no hydraulic pressure restored, what action should the driver take next to reduce speed?

  1. A
    Shift the transmission into neutral and rely on free-rolling momentum dissipation to stop
  2. B
    Abruptly pull and lock the parking brake lever without holding the release mechanism
  3. Downshift the transmission to a lower gear to use engine compression brakingAnswer
  4. D
    Engage the driveline retarder at maximum capacity while depressing the clutch pedal continuously

Answer

Downshift the transmission to a lower gear to use engine compression braking
When hydraulic brakes fail and pumping the pedal produces no pressure, the immediate next procedural step is downshifting into lower gears. This allows the engine's mechanical compression to absorb vehicle momentum and steadily reduce speed before the driver gently modulates the parking brake or seeks an escape route.

Step-by-Step Solution

1
Assess the failure state after initial emergency pumping fails
Confirm that hydraulic pressure cannot be rebuilt via the foot pedal.
Pumping the pedal is always the first tactical check for hydraulic failure; when ineffective, alternate retarding forces are required.
2
Engage engine braking by downshifting through gears
Engine compression begins dragging down road speed safely without locking wheels.
Lower gears increase mechanical engine resistance on the drivetrain, shedding speed prior to parking brake application.
3
Prepare auxiliary and emergency stopping methods
The vehicle slows to a speed where parking brake modulation or off-road escape routes can safely halt the unit.
Gradual speed reduction prevents violent spin-outs or loss of directional control.

Key Concept

Hydraulic Brake Failure Emergency Response Sequence
Estimated Time:1m 0s
Rate this question

Topics

Brake Failure

More questions from this topic