Braking on Downgrades and Emergency Procedures
What this domain covers
Grade strategy, brake fade, and what to do when brakes fail or a stop goes wrong.
Before the grade
Check brakes and air pressure at the top. Slow down and shift into a gear low enough that engine braking holds your speed - the same gear you would need to climb the grade. Do not coast in neutral and do not turn the engine off.
On the grade
Use light, steady pressure, or snub: apply firmly to drop speed 5-10 mph, release, and repeat as speed builds. Either way, avoid riding the brakes continuously. Brake fade comes from heat, not wear: drums and linings overheat, stopping power drops, and the pedal may feel long or spongy.
If brakes fail
Downshift progressively to use engine braking, look for an escape ramp (gravel or sand) and use it, and apply the parking/spring brake gradually rather than slamming it on, which can lock wheels and cause a jackknife. Sound the horn to warn others.
Worked example
A loaded tractor-trailer starts a long 6% descent at 55 mph in a high gear. The driver brakes hard and repeatedly; by mid-grade the pedal feels long and the truck will not slow. Reasoning: the brakes have faded from heat. Response: downshift, take the escape ramp rather than continue, and never try to "make it" to the bottom.
Traps that cost marks
- Riding the brakes down the grade instead of snubbing.
- Selecting a gear higher than needed for the descent.
- Slamming the spring brake on at highway speed.
- Passing an escape ramp and hoping the grade ends.