While descending a steep mountain grade, a driver presses the brake pedal and feels it go completely to the floor without creating any resistance. After rapidly pumping the pedal, hydraulic pressure is still not restored. Which of the following is the correct sequence of emergency actions the driver should execute to safely stop the vehicle?
- AShift into neutral, turn the ignition key to the off/lock position to shut down engine power, and immediately pull the parking brake handle up as hard as possible.
- Shift into a lower gear, pump the brake pedal to build any residual pressure, gradually apply the parking brake while holding the brake release, and direct the vehicle toward an emergency escape ramp or safe friction surface.Answer
- CMaintain the current gear to keep vehicle momentum consistent, shift into reverse if speed exceeds 40 mph, and swerve back and forth across the lane to use tire friction for deceleration.
- DAccelerate slightly to level out the vehicle's weight distribution, pump the accelerator pedal to vent brake line pressure, and coast until reaching flat terrain at the bottom of the grade.
Answer
Downshifting into a lower gear, applying the parking brake gradually while holding the release mechanism, and steering toward an runaway truck/escape ramp or natural friction barrier is the safest method to regain control during total brake failure on a steep grade.
When primary hydraulic brakes fail completely on a steep grade, downshifting utilizes engine compression to reduce speed. Simultaneously, applying the mechanical parking brake progressively prevents wheel lockup. Directing the vehicle toward an escape ramp or off-road friction zone provides a safe environment to bring the vehicle to a full stop.
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Key Concept
Total Hydraulic Brake Failure Emergency Protocol on Steep Grades