What is Engine Brake and How Does it Work?
You’ve probably heard the obnoxious noises some semi trucks make when slowing down. It’s not the brakes that are aurally...
You’ve probably heard the obnoxious noises some semi trucks make when slowing down. It’s not the brakes that are aurally assaulting you, it’s the Jake Brakes. Jake Brakes and engine braking, which function similarly but operate differently, help trucks and other vehicles slow down without using the brake pedal or traditional braking system alone.
Though they’re mostly used in large semi trucks and diesel-powered vehicles, Jake Brakes have been widely used for several years. Car Bibles’ editors don’t drive trucks for a living, but we have had plenty of experience with engine braking and can help break down the details to get you started on the right foot.
Let’s get rolling.
What Is a Jake Brake and How Does It Work?
The Jacobs Engine Brake is a diesel engine retarder that uses the engine to help slow down a vehicle. In many cases, though, people incorrectly use the terms “Jake Brake” and “engine brake” interchangeably. Jake Brakes are separately installed components that release stored compressed air from the cylinder at the top of the piston’s stroke. This stops it from returning energy to the crankshaft, which helps slow the vehicle.
A similar effect can be experienced in gasoline vehicles by lifting off the throttle pedal. The action restricts airflow and causes a high manifold vacuum that the engine’s cylinders work against. That reduces power and helps slow the vehicle.
The main benefit of Jake Brakes and engine braking is protection against wear and tear on braking components. It can also be safer for vehicles as they travel downhill, because it prevents overheating brakes and provides more predictable speed scrubbing.
Car Bible’s Glossary for Jake Brakes
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- Jake Brake
Jake Brakes are engine braking components that are installed on some diesel engines. They work by opening exhaust valves to the cylinders before the compression stroke ends. That releases compressed gas trapped in the cylinders and slows the vehicle.
- Engine Brake
Engine braking occurs when the accelerator pedal is released. That causes fuel injection to stop and a great reduction in airflow, which leads to a manifold vacuum. That vacuum works against the engine and slows the vehicle down.
- Brake Pads
In disc braking systems, brake pads are the component that help generate friction to slow the vehicle. They are mounted in calipers that “clamp” them down over a rotating disc (also called the rotor).
The transmission is mounted directly to the engine and converts its energy into momentum and rotations that drive the wheels. Transmissions come in a variety of configurations, including automatic transmissions, manual transmissions, and continuously variable transmissions.
Your Questions, Our Answers on Jake Brakes
Q: Are Jake Brakes Illegal?
A: Jake brakes and engine braking both create a ton of noise from the engine and exhaust as they work. This has caused some areas to ban their use in neighborhoods and places where an abrupt loud noise would be less than optimal.
Q: Can I Install Jake Brakes On My Truck?
A: You can, but there are several extra steps that need to be taken for the system to function properly. The truck’s computer may need to be updated or modified, and the physical installation itself is nothing to sneeze at. It’s best to get a professional to help with the job if at all possible.
Q: Is a Jake Brake Bad For My Engine?
A: No. The only situations where a jake brake could prove harmful to an engine is if the driver allows the vehicle to push the engine’s RPM above its maximum limit.
Video on Jake Brakes
Car Bible’s Favorite Jake Brake Related Products
It can be hard to find the right projects to help you with your Jake Brake project. That’s why we’ve selected a few of our favorites to get you started down the right path. The Engine Brake Adjustment Tool, Feeler Gauge Jake Brake Tool, and Power Stop Brake Kit are useful, affordable, and well-reviewed.
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