Emergency Braking, Parking Brakes, and Safe Driving Practices
Domain 4, Emergency Braking, Parking Brakes, and Safe Driving Practices, tests what you do when normal braking is not enough, and how to park and descend grades without creating an emergency. The exam favors practical judgment over memorized slogans.
Emergency braking
If service brakes fail, use the parking/emergency spring brakes by pulling the yellow knob gradually-not all at once-to avoid locking the wheels. Downshift as speed drops and look for an escape ramp. With ABS, brake firmly and steer; do not pump. Without ABS on a slippery surface, use controlled braking (firm pressure without wheel lock) or stab braking (apply fully, release when wheels lock, reapply).
Parking
Set the parking brake, chock wheels on a grade, and turn wheels toward the curb when facing downhill (away when facing uphill) if there is a curb. Leave manual transmissions in the lowest gear or reverse; automatics in Park. Do not use the parking brake to stop from highway speed except in an emergency.
Descending grades
Select a lower gear before the downgrade, not after brakes heat up. Use engine braking and light, steady brake applications. Do not ride the brakes; heat causes fade. If brakes smell hot or fade, stop and let them cool. Colorado grades can be long and steep; escape ramps are for vehicles that lose braking.
Worked example
A loaded truck starts down a long grade in high gear. The driver rides the brakes; halfway down, the pedal goes soft and speed climbs. Reasoning: the brakes have faded from heat. The driver should downshift, use engine braking, apply the parking brake gradually if needed, and use an escape ramp if speed cannot be controlled. The error was starting the grade in the wrong gear and riding the brakes.
Traps
Pumping ABS brakes, using the parking brake for routine stops, parking without chocks on a grade, and waiting to downshift until brakes fade are all mark-losers. Also remember that spring brakes are for parking and emergencies, not for normal speed control.