Mountain Driving 101: Descending Safely
There is an old trucking proverb: "You can go down a mountain too slow a million times, but you can only go down a mountain too fast once."
Gravity is unforgiving to an 80,000 - pound vehicle.The friction material on your brake pads can heat up to over 600°F in seconds, leading to "brake fade"(where brakes fail completely) or causing the tires to catch fire.
The Secret: Engine Braking(Jake Brake)
The key to surviving a steep downgrade is utilizing the Engine Retarder(the Jake Brake).The Jake Brake alters the engine's exhaust valves, turning your diesel engine into a massive air compressor that holds the truck back without using the wheel brakes.
1. Choose the Right Gear BEFORE the Descent
You cannot safely downshift on a steep 6 % or 7 % downgrade.You must be in the correct gear at the crest of the hill.
- The Rule of Thumb: You should go down the mountain in a gear at least one full gear lower than the gear you used to go up the mountain.
- If it's a 6% grade and you are loaded heavy, you might need to be in 5th or 6th gear, maxing out at 25 mph.
2. "Snubbing" Technique
If the engine brake alone isn't enough to hold the truck's speed, do NOT ride the foot brake continuously.This will glaze the pads and boil the brake grease.Use the "Snubbing" method:
1. Let the truck reach your "Safe Maximum Speed"(e.g., 35 mph).
2. Apply firm, steady pressure to the foot brake to reduce speed by 5 mph(down to 30 mph).This should take about 3 seconds.
3. Release the foot brake entirely.Let the brakes cool as gravity pushes the truck back up to 35 mph.
4. Repeat.
3. Pay Attention to Warning Signs
- The Smell: Your nose will warn you before disaster strikes.Hot brakes have a distinct, acrid metallic / burning smell.If you smell it, you are braking too hard.
- Smoke: Look in your mirrors constantly.If you see white or blue smoke pouring from your trailer wheels, your brakes are actively failing and on the verge of fire.
4. Runaway Truck Ramps
If you experience total brake failure, look for a runaway ramp immediately.Do NOT attempt to "ride it out" to the bottom.Runaway ramps are filled with deep gravel designed to safely sink the truck and stop it safely.It will destroy the truck's undercarriage and require a tow truck, but it will save your life.