December 21

What are Jake Brakes and Why Do People Use Them?


Last Updated on February 24, 2022

There’s a lot that goes into creating trucks, big or small. Some have unique components not present in others. One great example are Jake Brakes. These often get used on heavy duty trucks, but what are Jake Brakes and why do people use them?

A Jake Brake is an engine brake that gets equipped to heavy haul trucks, but is different from standard brakes. They’re not located near the tires, but at the engine. For this reason, they’re sometimes called engine brakes. 

The technical term for a Jake Brake is a compression release engine brake. They function by releasing the compressed air in the engine via the exhaust valves to quickly reduce speed. An open exhaust vent creates pressure that prevents the piston from powering the down-stroke of the crankshaft.

The term Jake Brake is a shortening of the phrase “Jacobs engine brake retarder”. The name comes from Jacobs Vehicle Systems, the manufacturer. 

After founding and retiring from the original engine manufacturer, Cummins Inc., Clessie Lyle Cummins, founded Jacobs Vehicle Systems. He sought to devise a solution that reduced overheating and fires when heavy haul trucks brake, especially while traveling downhill on steep grades. 

Cummins may have even had a personal experience that directed this ambition.

As the story goes, Cummins traveled with two others from New York to California. They drove in a diesel truck outfitted with sleeping bunks, plenty of storage space, and a stove. Their vehicle may have been the first truck to motorhome renovation. Except, the modern motorhome hadn’t been invented yet. 

The purpose of this 3, 214 mile cross-country trip was to test the durability of the truck’s diesel engine. The fuel cost for the entire trip was $11.22 (about $200 in today).

Near the end of the trip, the crew were driving down the Cajon Pass on the old Route 66. The grade was steep and a train was traveling across the road ahead of them. The trio barely missed T-boning the caboose when the truck crossed the tracks. 

Jake Brakes - truck driving

Why are Jake Brakes so great?

Using Jake Brakes instead of regular brakes saves the latter from wear and tear, and produces no damage to the engine. Some truckers have reported that using Jake Brakes extends traditional brake life by two or three times. When your truck (plus trailer) has 18 wheels, that’s a lot of brakes to replace. Having an engine brake will save you plenty of money in the long run.

Can Jake Brakes hurt the engine?

Using a Jake Brake doesn’t cause any damage or wear to other components. The caveat is that the engine oil isn’t low and the engine has had time to reach optimal operating temperature. If a trucker uses the Jake Brake with a cool engine or low engine oil, there is a risk of engine damage. 

Jake Brakes are also more likely to cause jack knifing on slippery roads. Traditional brakes are therefore better to use when there is ice or pools of water on the driving surface. 

Do Jake Brakes use more fuel?

There is some debate as to whether engine brakes use more fuel. The consensus seems to be that if Jake Brakes do use more fuel, the increased cost is a tiny fraction of the money saved by extending traditional brake life.

Also, engine brakes decrease stopping distance, which enhances safety.

However, there is a drawback. Jake Brakes make a loud noise when used. The sound is unpleasant and boisterous enough to penetrate people’s houses. Most people get either annoyed, startled, or awoken by the noise. This has led some to seek out local government representatives to mitigate Jake Brake usage in their neighborhoods. 

Jake Brakes - information sign
Image Credit: Wikimedia

Are Jake Brakes illegal?

Many non-truckers despise the use of Jake Brakes. The loud sound is uneasy on the ears, sometimes startling, sometimes waking people at night. In addition to those problems, there have been reports of truckers using Jake Brakes to deliberately scare pedestrians, even children. Some reports suggest other drivers have been targeted too, people who perhaps drove in a way that annoyed the trucker. 

In response to these complaints, municipalities have posted signs along truck routes in order to curb Jake Brake usage. Common signage includes:

  • No Jake Brakes
  • Compression Braking Prohibited
  • No Engine Breaks
  • Brake Retarders Restricted
  • Unmuffled Compression Brakes Prohibited
  • No Jake Brakes Within City Limits
  • Trucks Please No Jake Brake

Ultimately, Jake Brake usage is illegal in some areas. Other communities just have noise restrictions, which still makes using Jake Brakes illegal. Truckers must watch out for this signage.

Whether a municipality has the power to enforce “No Jake Brake” zones or not sometimes gets determined by higher forms of government. In 2004, the state of New York determined that “villages” could not regulate state-owned infrastructure even when it passes through their community. The “No Jake Brake” signs had to be removed. 

However, other communities have been allowed to erect “No Jake Brake” signs. The city of Chesterfield, Missouri, for example, has been allowed to create laws banning Jake braking. It’s punishable by a $500 fine and up to 90 days in jail.

Truckers sometimes complain that changes in road speed are too abrupt. Within a short distance—and without any signs warning of the upcoming speed change, the speed limit drops from 55 mph to 30 mph. 

In a case such as this, using Jake Brakes is safer than using traditional brakes. 

If a trucker takes the time to write to a municipality and explain the need for signs warning of speed limit changes, these problems can be eliminated for all truckers. 


The company Jacob Vehicle Systems still exists today, and continues to produce Jake Brakes. They are in 100 percent of Cummins truck engines (naturally) and Detroit Diesel truck engines. They also have significant market share on Navistar truck engines. Volvo produces their own compression release engine brakes for the Volvo and Mack brands of trucks. They do not rely on Jake Brakes.

The manual that the company creates begins with the warning that Jake Brakes are a vehicle-slowing device, not a vehicle-stopping device. A trucker still needs to apply the truck’s standard brakes to come to a full stop.
Hate ‘em or love ‘em, Jake Brakes have proven helpful to a number of truckers. Maybe you’re one and looking to hit the road with or without Jake Brakes, there’s a selection of heavy duty trucks waiting just for you.


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