A heavy commercial vehicle suffers a complete failure of the primary service brakes while traveling on a rural highway. The driver has already downshifted to a lower gear to utilize engine braking. What is the correct next step to safely bring the vehicle to a stop using the emergency braking system?
- AFully lock the parking brake immediately and maintain continuous pressure without releasing it, regardless of whether the drive wheels lose traction.
- Apply the parking brake gradually while keeping a hand on the release control to modulate pressure if the rear wheels begin to skid.Answer
- CSwitch the auxiliary retarder to its highest setting on wet or slippery pavement to compensate for the lost braking force.
- DRely on mechanical pushrods to self-correct excessive travel at highway speeds and continue pressing the unresponsive pedal.
Answer
Apply the parking brake gradually while keeping a hand on the release control to modulate pressure if the rear wheels begin to skid.
When primary service brakes fail completely, the driver must downshift to use engine braking and then apply the parking brake carefully. Holding the parking brake release control is critical so that braking force can be instantly eased off if the rear wheels lock up, maintaining directional control while slowing down.
Step-by-Step Solution
Key Concept
Controlled Parking Brake Application and Modulation During Service Brake Loss
Estimated Time:1m 0s