If you’ve heard an annoying squeaky sound coming from a semi-truck as it is slowing down, well, you’ve heard a jake brake. Though not loved by many due to the sound it makes, this function is extremely useful: It can extend the life of a brake and bring a large vehicle to a safe stop. Perhaps the name of this brake has piqued your curiosity now. So what is a jake brake exactly, and how does it work? DriveRevolve will dive into that here. Follow us as we explain the basics of this fun auto part – we will have you covered in no time! 

What Is A Jake Brake? 

Before you ask, no, the name jake brake has nothing to do with the legendary ska-punk band “Less Than Jake.” It is a shortened form of the phrase “Jacobs engine brake,” which totally makes sense since Jacobs Vehicle Systems introduced the brake.

What Is A Jake Brake?
What is a jake brake on a truck? – Source: jacobsvehiclesystems

According to the manufacturer, this invention is basically a diesel engine retarder that utilizes the vehicle’s engine to slow it down. Also referred to as an engine brake or decompression brake, it is typically found on large trucks instead of passenger cars. In general, the only vehicles with this system are too huge to stop with standard brakes effectively. 

How Does A Jake Brake Work? An In-Depth Explanation 

Jake brake VS engine brake are actually the same

Most cars nowadays use internal combustion engines. When drivers of such cars let off the accelerator, the vehicle’s forward momentum will keep the crankshaft turning. Diesel, with the noteworthy exception of the Bugatti Chiron‘s engine, is built without a throttle butterfly, so a full charge of air is always pulled into the cylinder. As a result, even when the fuel supply is shut off, every time the cylinder compresses air, all of the energy passively created during the process returns to the crankshaft. This restricts the vehicle’s engine braking. 

To deal with this problem, the jake brake features an add-on hydraulic system that runs off the engine’s oil. Once activated, the fuel injector’s rocker arm will drive the engine’s exhaust valves. This released the pressurized air in the master cylinder at the top dead center of the engine so that the energy won’t go back to the crankshaft. Instead, the energy is released through the exhaust system. That’s how this type of brake slows a large vehicle down or stops it altogether with little to no use of the service brakes. The power of this brake is much more than the standard braking system. 

Are Jake Brakes Illegal? 

Jake brakes are illegal
What does no engine brake mean? Does it mean jake brakes are illegal? – Source: CapeNews

Well, there is no definitive answer to this question. To what extent jake  brakes are prohibited varies from state to state. Some areas encourage the use of engine brakes, whereas others strictly ban them. 

Why is that, you might ask? As mentioned, the jake brakes are very loud. Although they are wonderful for avoiding wear and tear on a vehicle’s service brakes, their noise can disturb the residential quarters. That’s why this function is illegal in some states. 

However, this shouldn’t be your concern. Engine brakes can be activated using a switch, which means you can turn this feature off. Additionally, signage on the roads can let you know when you can’t use jake brakes. Along the way, you can spot signs that say, “No jake brake allowed,” or “Engine brakes are prohibited.” 

The real dilemma is whether or not a jake brake can harm your engine. 

Can A Jake Brake Damage A Truck’s Engine? 

Does Jake Brake Damage A Truck’s Engine?
With some precautions, using a jake brake can be beneficial for your vehicle – Source: The Drive

Why do I call it a dilemma? An engine brake can benefit your auto parts, but only if you use it correctly. Otherwise, it will become a double-edged sword. 

As mentioned, the jake brake uses your engine to slow down and ultimately stop the vehicle. If there isn’t enough oil, utilizing it can lead to severe damage to the rig’s engine. What’s more, if you push the engine’s range of operation over the maximum limit when you use the jake brake, it also leads to damage. 

That’s why I have compiled some safety tips for those who are not yet familiar with this useful yet complicated car part. 

Tips For Using The Jake Brake 

Since this specific type of brake is only found in some vehicles, drivers might have trouble using it. The advice below will help you use the jake brake safely and effectively: 

  • Conduct route surveys before each trip to become familiar with the road. This is important, especially when the jake brake is prohibited in some areas due to the loud noises it releases. 
  • Since the brake works by using the engine’s power, make sure to keep the engine oiled up. For your own safety, the engine should be working at the right temperature, too. 
  • Before setting out on a long trip, test the jake brake several times to ensure that the brake is in good working order. 
  • According to experts, the optimal range of operation for the jake brake is between 1,100 and 1,400 revolutions per minute. Although the brake can function at greater speeds, excessive use of this range may accelerate the motor’s depreciation.
  • Since the jake brake’s position of strength depends on the engine, each driver can choose the position to suit their engine and the road condition. If your brake has 3 positions, the first 2 are often the best to use in extreme weather. The third position is the most suitable for daily use. 
  • Using the engine brake when the vehicle’s gears are shifted is not a good idea since the engine might stall out. Also, try not to stop the truck with the jake brake when it is not moving at a consistent and controlled speed. 
  • If possible, avoid using the jake brake in extreme weather conditions. The brake is not intended for optimal usage on slippery or icy roads. 

If you have to use this braking system in poor weather conditions, you should ensure that the tractor-trailer unit is positioned right behind you. Misalignment, in this case, can cause serious issues. The vehicle might jackknife and slide out of control, leading to a severe accident. 

Frequently Asked Questions

The differences between jake brake and exhaust brake

“How Do I Know If My Car Has A Jake Brake?”

If you are unsure whether your vehicle has a jake brake, the answer is probably no. This type of brake is commonly found on trucks or semi-trucks, as well as large vehicles that require more power to slow down or stop. It is not designed to use on your Honda Talon 4 Seater. Some modern trucks feature engine brakes, but they are sporadic cases.  

Is A Jake Brake The Same As An Exhaust Brake? 

Jake brake and exhaust brakes are the two types of brake retarder systems, but the ways they operate are entirely different from each other. As you already know, a jake brake allows compressed air in the cylinder to escape. On the other hand, an exhaust brake keeps the air from the engine in the exhaust system. This results in back pressure, which slows down the engine’s rotation. 
While both brake systems have their own strengths and weaknesses, here is the main difference: The exhaust brake functions quietly, while the jake brake is notoriously noisy. Most drivers say that the latter resembles the sound of a machine gun. So if you hear an ear-piercing noise as you brake… well, you know what type of brake it is! 

Do Jake Brake Use More Fuel?

Basically, yes. 
There is still some disagreement over whether or not engine brakes increase the amount of fuel consumed. However, most mechanics agree that this system does use more energy. “The excessive fuel only costs a small fraction of the expense saved by extending standard brake life, so I think it is a worthy trade-off,” Pete from “Swanage Tyres and Tuning” stated. 


Now that you have the answer to “What is a jake brake?”, you probably realize one thing: The general public takes a dim view of this system. Across the U.S., you will see the “NO JAKE BRAKE ALLOWED” sign in numerous locations, banning brake use. 

Yes, the jake brake has a deafening roar, which is a massive nuisance for those who live near the highways. After getting annoyed, awoken, or startled by this noise, residents become too irritated by the loud sounds of this feature that they are vehemently against it. 

These folks fail to realize that the engine brake is meant for safety. Its ability to stop a big vehicle can save both the drivers and the pedestrians from potential risks. The noise created by the jake brake is loud, there’s no disputing that. But is it right to prohibit it when it can protect your life? Let us know what you think in the comment! 

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