What is "Jake Brake"?
Asked by
Trillian (
21153
)
August 29th, 2010
Every day when I go to work as I’m driving on the off ramp, I see a sign that says; “Warning, no Jake Brake”
What can this possibly mean? Is it a trucker expresson? I think to myself “Today I’m going to remember to ask someone at work.”, and by the time I get there I’ve fogotten. Fortunately, I have you.
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10 Answers
They are the air brakes on a big rig. They are loud and make a loud rattling “BAAAAHHHHHHHHH” like sound.
In quiet neighborhoods they put up signs due to the noise.
Thank you both. I wonder what people are supposed to do to slow down if that’s all they have…
According to Cecil at Straight Dope, if you see a sign that specifically mentions “Jake Brake,” the company wants you to photograph it and tell them exactly where it is so they can raise hell with that township.
They are not air brakes @Dog. They are how truckers use the engine itself to slow the big rig without using the air brakes. And yes they are quite loud.
Has nothing to do with the air brakes, Jake Brake ,is a engine brake that uses the engines compression to slow the rig down on hills,and depending on the exhaust system the truck has ,yes they can be very loud.
Source: over 20years being a transport driver.
@Trillian, especially in hilly terrain, a heavy tractor trailer relying only on its air brakes on the wheels would be in trouble. Friction brakes (even on your car) can heat up to the point where they no longer function properly. That’s why, if you’re in the mountains, you’ll often see a long straight-away with mounds of dirt alongside the road when you’re going downhill. It’s a safe crash zone for runaway trucks that can no longer stop or slow down.
So on long, steep downhills, a trucker will rely more heavily on their engine compression braking instead. The only negative side effect of that is the loud noise. And, of course, it cannot bring the truck and trailer to a full and complete stop all by itself.
Worst case, if a truck driver found himself in a runaway situation where his wheel brakes were out of commission, he would definitely use the jake brake to slow his rig down to bring it under control, even if there was a local ordinance against it.
@robmandu Hmmmm, I’ve seen those long dirt hoo-yas, and I’ve seen once or twice a truck still in them.
The exit off of 52 is flat, as is 52 all aross the southern tip of Ohio. Coming off of 52 to the bridge over the Ohio River going to WV is also flat as a pancake, so I guess that there would be no need for all that fancy schmancy braking. The ramp speed is 40, then 25 and Chesapeake cops are just waiting to give people tickets….
It’s actually a compression release braking assist system used with diesel engines. Unlike gasoline engines, diesels do not provide compression braking when the throttle is lifted since the intake air supply is constant. Engine resistance braking is only possible if this cylinder air pressure is relieved. The “Jake Brake” is an additional valve in each combustion chamber and a control system which allows the air pressure to be relieved. This system is completely separate from the air brakes on these vehicles. The intention of these systems is to minimize wear on the brake system and improve fuel economy.
The signs you saw were posted because of noise concerns. These brake assist systems can increase the exhaust noise of vehicles with inadequate mufflers.
a type of engine brake designed to slow a semi (big truck) without wasting (damaging) the actual brakes designed to slow the wheels.
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