Driving down a long, steep downgrade can be daunting for even the most seasoned drivers. Maintaining control of your speed and vehicle is critical for safety. While the engine braking provides some slowing power, properly using your brakes is key to keeping speeds in check on steep downhills. Follow this guide to learn when and how to apply brakes for maximum control.
Why Engine Braking Isn’t Enough
On very steep downgrades, the natural engine braking may not be sufficient to prevent speed buildup. While helpful, relying solely on engine braking can lead to brake fade, loss of control, and excessive speed. Supplementing with proper brake application techniques is vital.
Method for Safe Brake Use Downhill
1. Shift into proper low gear before descent
As you approach the downhill grade, shift the vehicle into the appropriate low gear based on the severity of the slope and your vehicle’s specs. For very steep hills, 1st or 2nd gear may be appropriate. Being in a low gear maximizes the engine braking available to help control speed. Try to shift down well before the steep grade begins, if possible when cresting the hill before the descent. Shifting mid-descent can be difficult and hazardous.
2. Determine your target “safe” speed
Consider the length and steepness of the grade, weather conditions, your vehicle weight and capacity, and your personal comfort level. Choose a conservative target speed – usually 25-45 mph is appropriate for most large commercial vehicles. The target speed should be well below the posted speed limits. If conditions are poor due to rain, snow, ice etc., reduce your target speed even more. It’s easier to go slower than faster.
3. Apply brakes when speed reaches target
As you start descending and your speed builds, do not apply brakes until reaching your pre-determined target speed. Once at the target speed, apply steady brake pressure to gradually reduce speed by about 5 mph. Brake just hard enough to feel the vehicle slowing down but not so hard as to lock up wheels and skid. Bring your speed down approximately 5 mph below the original target.
4. Release brakes when 5 mph below target
When about 5 mph under your original target speed, completely release the brake pedal. Allow the vehicle to coast back up to your target speed. Avoid tapping or pumping the brakes. Use a single, smooth brake application and release cycle.
5. Repeat brake application cycle
Each time your speed climbs back to the original target, apply the brakes again to reduce speed by about 5 mph. Continue repeating this process of braking and releasing all the way down the long descent. This prevents brake overheating while controlling speed. Adjust pressure as needed if conditions change requiring more or less braking.
6. Use proper gears
Remain in the low gear you pre-selected through the entire downhill. Avoid trying to shift gears during the descent as this can cause loss of control. Use your transmission responsibly to assist braking and control.
Example Safe Braking Down a Hill
For example, if your determined “safe” speed is 40 mph:
- Do not brake until speed reaches 40 mph.
- At 40 mph, apply brakes to gradually decrease speed to 35 mph.
- At 35 mph, release brakes completely.
- Allow speed to return to 40 mph.
- Repeat cycle of braking and release all the way downhill.
Benefits of This Braking Technique
Applying the brakes in a controlled, cyclic fashion when descending steep grades provides several key benefits:
- Prevents overheating brakes – Allowing time between brake applications gives the friction surfaces a chance to cool down. This reduces heat buildup which can lead to brake fade. Overheated brakes are a major cause of loss of control in hills.
- Maintains control and stability – Making gradual speed adjustments through braking cycles avoids sudden speed changes. This keeps the vehicle balanced and stable, enhancing control. Slamming the brakes can destabilize the vehicle and cause brake lockup.
- Maximizes engine braking – By using the engine’s resistance as the primary speed regulator, the friction brakes are used less. This reduces wear and tear on the service brake system. Engine braking also provides smooth, steady slowing power.
- Keeps speeds conservative – Cyclical braking maintains speeds well below speed limits and within a controlled range. High speeds compound problems if brakes begin to fade. Lower speeds give more time to react and adjust.
- Reduces brake fade – Keeping brakes from overheating greatly decreases the chances of brake fade. Fade can occur when brake components overheat and lose stopping power. Gradual braking prevents overtaxing the system.
- Check brake condition and specification limits before steep descent.
- Use extra caution in wet or icy conditions.
- Downshift before beginning descent.
- Drive in the proper gear at all times.
- Avoid riding the brakes for prolonged periods.
- Be prepared to stop at any point if necessary.
How do I know what a safe downhill speed is?
Consider the grade, vehicle weight, road conditions, weather, and your comfort level. Stay well below posted speed limits. Generally 25-45 mph is a good target range.
Should I ride the brakes all the way down?
No. Riding the brakes can cause brake fade and loss of control. Use the recommended cycle of braking and release.
What if my speed gets too high during descent?
Carefully apply steady brake pressure to reduce speed. But avoid locking up the wheels or braking too hard. Downshift if possible. Pull over if unable to control speed.
Why downshift before the hill?
Being in a lower gear maximizes engine braking and vehicle control. Trying to downshift during descent is risky.
What if my brakes start fading?
Fade occurs when brakes overheat. If you feel fade, avoid using brakes if possible until they can cool. Downshift and use uphill areas to slow. If necessary, carefully pump brakes to slow.
Can I go faster than the safe speed?
It’s not recommended. Speeds much above your target increase risks greatly. Add 10 mph at most above your safe speed.
Driving down steep grades presents unique challenges. By following these brake application techniques, you can maintain control and enjoy the descent safely. Allowing breaks between braking, maximizing engine assist, and keeping speeds in check are the keys. With practice and caution, even the steepest grades can be navigated with confidence.