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Have you ever heard a loud, rumbling noise behind a semi-truck or other large vehicle on the highway? That’s Jake Braking in action. Also known as engine braking, it is a useful method for semi and freight truck drivers to slow down while minimizing wear and tear on their vehicle’s service brakes. But does Jake Braking have unintended consequences? Does engine braking damage the engine?

How does Jake Braking work? 

A blue semi, potentially using Jake Braking to slow it down, driving down a wooded area.
Semi on the road | Getty Images

Jake Brakes are fitted to diesel engines to reduce the strain on the service brakes when slowing down quickly. This is especially useful for large vehicles that can take longer to slow down. 

Truck drivers can enable it by flipping the engine brake switch. According to Matheson, “As a big rig is working, the air is forced into the engine cylinders as it enters the intake valve. This causes the air to compress, which converts it into energy that can be distributed. Usually, the pistons take that energy and guide it to the rest of the vehicle to produce power. However, when a Jake Brake is activated, that air is pushed out the exhaust valves instead of being used to power the crankshaft and down-stroke.”

Does Jake Braking damage engines? 

If done incorrectly, it can cause severe damage to your engine. According to Matheson, there are several factors to remember to ensure you do it properly. Drivers should make sure their oil isn’t low. Damage can occur if an engine brake is used when oil is low. The truck drivers should let the engine warm up as well. Performing Jake braking with a cold engine could result in a damaged one. Lastly, it’s important that the driver not allow the weight of the truck going downhill to push the RPMs over the engine’s RPM limit. Remembering these factors can save you a lot of money in repairs.

Other disadvantages 

Since Jake Brakes are so loud, they have been banned in many cities for fear of disturbing residents at night with their rumbling noise. Apex CDL Institute states that some towns will even fine truckers if they use their Jake Brakes within a specific limit outside town. So, be sure you know the law regarding Jake Brakes before using them in your travels.

The bottom line

In summary, both pros and cons are associated with using Jake Brakes when driving trucks or semis. While its primary benefit is reducing the stress placed on service brakes while slowing down quickly, it should not be overused. Misusing these brakes could lead to overheating or extensive maintenance.


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