Jake Brakes and Mountain Driving for Truckers

For truck drivers

Updated September 28, 2026

This guide takes a loaded truck down a mountain grade, start to finish. The methods come from the Colorado Commercial Driver License Manual and the Colorado Department of Transportation (CDOT). Driving a pickup with an exhaust brake? Check your engine maker’s guide. This page is about heavy trucks.

What Is a Jake Brake?

“Jake Brake” is a registered trademark of Jacobs Vehicle Systems. That is where the name comes from. Drivers use it for any engine compression release brake, whoever made it.

The CDL manual calls these devices retarders. It says a retarder:

• Helps slow the vehicle, so you use your brakes less
• Cuts brake wear and gives you another way to slow down
• Slows the drive wheels only, not every wheel
• Can be turned on or off by the driver, and on some trucks the strength can be adjusted

A retarder is not built to bring the truck to a full stop. It holds your speed back. Your service brakes still do the stopping.

How a Jake Brake Works

An engine brake changes how the engine’s exhaust valves open. Air the engine has squeezed is let out through the exhaust, and that slows the truck. Many are switched on when you let off the accelerator. Some work from a separate control or the brake pedal.

Here is what that means in the cab:

• It works when you are off the throttle. The manual says a retarder that is on applies its braking power whenever you let up on the accelerator all the way.
• It is strongest in a low gear. The engine’s braking effect is greatest near governed RPM with the transmission in the lower gears.
• It can make you skid. On a wet, icy or snowy road, the drive wheels can lose grip. The manual says to turn the retarder off when the road is slick.

Winter note: the manual’s winter section says not to use the engine brake or speed retarder on slippery roads. Winter grades in Colorado can also bring chain law. See our guide to the Colorado chain law for truckers.

Jake Brake vs Engine Brake vs Exhaust Brake

The names get mixed up. The CDL manual lists four types of retarder: exhaust, engine, hydraulic and electric. Here is how the common terms line up.

Whatever the type, the rules below are the same. Know how your truck’s retarder works, and never count on it to stop you.

Brake Fade and Why Long Grades Are Dangerous

Going down a long grade, gravity keeps adding speed. If you hold the truck back with the service brakes alone, they heat up. Then they start to fade.

The manual explains fade this way. You have to press harder and harder to get the same stopping power. Keep braking hard and they can fade until you cannot slow down or stop at all.

Two things set up a fade:

• Too much braking. Brakes fail from heat when you use them too much and do not rely on the engine.
• Brakes out of adjustment. Those brakes stop doing their share. The rest overheat and fade. Brakes can go out of adjustment fast when they are used a lot, so check them often.

CDOT’s hot-brakes guide lists the warning signs: a burning smell, squealing, smoke, a soft brake pedal and less stopping power.

How to Take a Mountain Grade

Every step below comes from the CDL manual (section 2.16) or CDOT’s hot-brakes guide.

1. Know the grade before you get there. Find out about long, steep grades on your route. If you can, ask drivers who know them what speeds are safe.
2. Check your brakes at the top. CDOT asks every driver to do an extra inspection before Colorado’s steep grades. CDOT lists brake check areas around the state.
3. Pick a safe speed. Base it on your total weight, the length and steepness of the grade, the road and the weather. Never go over a posted speed limit or a “Maximum Safe Speed” sign.
4. Pick your gear before the descent. Shift down before you start down, not after. Once speed builds, you may not get into a lower gear, or back into any gear.
5. Let the engine hold you back. The engine’s braking effect is your main tool. The manual calls the brakes “only a supplement” on a long or steep downgrade.
6. Brake in short, firm steps. Use the method in the card below, and repeat it to the bottom.

Which gear? CDOT’s guide says to go down steep hills in the same gear you climbed them in. The manual adds a warning. Modern trucks have less friction and drag, so you may need a lower gear going down than going up. Know what is right for your truck.

Runaway Truck Ramps

A runaway truck ramp, also called an escape ramp, is a lane off the highway that stops a truck with no brakes. It uses a long bed of loose, soft gravel. Some ramps also turn uphill.

The manual is plain about it. If your brakes fail on a downgrade, your best hope is an escape ramp. If there is one, use it. Signs tell you where they are, and ramps usually sit a few miles from the top of the grade.

If there is no ramp, take the least dangerous way out you can, such as an open field or a side road that flattens out or turns uphill. Do it as soon as you know the brakes are gone. The longer you wait, the faster you go.

Do not use a highway exit instead of the ramp, CDOT says. Its guide adds that you may owe a tow bill, but CDOT and the State Patrol will not ticket you for using a ramp. You can be cited if you cause a crash because you did not use one.

Runaway truck ramps on I-70 in Colorado

CDOT rebuilt the eastbound Mount Vernon ramp, just east of Genesee, and opened it on June 2, 2024. Its guide also lists ramps on other Colorado highways, including US 40, US 50, US 160 and US 550. Before you go, check road conditions on COtrip.

“No Engine Brake” Signs and Noise Rules

Engine brakes can be loud. That is why you see signs coming into some towns. Most of these rules are local. A city or county passes a noise rule, and the sign on the road tells you it is there.

In Colorado, CDOT lets counties and cities post engine brake signs on state highways, under set conditions:

• The local police must commit to enforcing the rule.
• Signs are not allowed on freeways or interstates.
• CDOT prefers them at the city limit or county line.
• The standard sign reads “Truckers Engine Brake Mufflers Required.” A version near the state line also lists a $500 fine.

There is a federal noise rule too. It caps how loud a motor carrier’s truck can be on the highway, measured in decibels at a set distance (49 CFR 325.7). A 2004 Connecticut legislative report notes that engine brake noise is part of exhaust noise and can be controlled with a working muffler.

The CDL manual’s advice is short: retarders can be noisy, so be sure you know where their use is allowed.

Mountain Freight Out of Denver

Denver is Accelerated’s home base. Our operational yard sits in nearby Parker, Colorado. From here, drivers run rail-head and regional lanes across the Rocky Mountain region, moving new vehicles for the automakers, the same work Motor Car Auto Carriers did before it became part of Accelerated.

A loaded car hauler on a mountain grade is exactly where everything on this page counts. Our rigs are pulled by Peterbilt, Western Star, Volvo and Freightliner tractors and carry up to nine cars. See the rigs we run. Winter adds chains to the job. Our guide to chain laws by state covers the western states.

Sources

Last checked September 28, 2026. Ramp locations and sign rules can change. Follow the signs on the road and your truck maker’s guide for your retarder.

1. Colorado Commercial Driver License Manual, June 2023 (PDF): 2.3.4 Retarders, 2.13 Driving in Winter, 2.16 Mountain Driving, 2.17 Driving Emergencies
2. CDOT, Hot Brakes and Runaway Truck Ramps of Colorado (PDF)
3. CDOT, eastbound I-70 Mount Vernon emergency escape ramp opens, June 2, 2024
4. CDOT Freight, The Mountain Rules
5. CDOT, Engine Brake/Noise Ordinance Sign Guidance, 2025 edition (PDF)
6. Connecticut Office of Legislative Research, Jake Brakes, report 2004-R-0741
7. 49 CFR 325.7, Allowable noise levels