What is jake braking?

[Douglas]

Will someone tell me what jake braking is?

[Windwalker]

Will someone tell me what jake braking is?

More correctly termed "ENGINE BRAKING". It's the system that produces the loud noise when a large truck descends a hill. It was designed to help drivers maintain control over their speed going downhill without using the brake shoes. Think of it as "the opposite of acceleration".

The term "JAKE BRAKE" comes from what was the most popular system for years made by "JACOBS BRAKE SYSTEMS".

[Douglas]

Oh. It'd be kind of like putting it in reverse and giving it just a little bit of acceleration to slow it down.

How does it work? Is there a button you press that causes it to come on?

[Skywalker]

Its a function of mechanical and quick adjustment of the timing of the valves to cause detonation in the cylinder at a different time than the acceleration stroke.... causes the truck to slow or maintain speed down a hill.

Some are automatically turned on when you take your foot off the accelerator, or when the on/off switch is set to on. Or some trucks even have an automatic feature that if the truck exceeds more than a couple of mph over its set speed on cruise control....the jakes will come on in stages.

[shyykatt]

...its a wonderful sound..

[rcso]

When your cylinders pump in a normal car the air gets compressed. When compressed on the top of the stroke it's super hot and that's when the little bit of gas is pumped in. That explosive energy is used to make your car go.

The Jake brake completely changes all this, redefining what the valves do as each piston moves up and down. With the fuel flow terminated, the upward moving first stroke still compresses the air to very high pressure. As we said above, this transfers mechanical energy into heat as the air becomes highly compressed. If nothing else were done, most of this energy would be recovered, except for frictional losses, as the cylinder moved back down and the compressed air expanded. The Jake brake, however, opens the exhaust valve just as the air reaches maximum compression, dumping all of that energy in an almost instantaneous explosive release. The result is a very effective slowing of the vehicle as mechanical energy is converted to heat and then dumped. The Jake brake effectively transforms the internal combustion engine into an air compressor.

http://or.essortment.com/jakebraketruck_raio.htm

[Jackrabbit379]

...its a wonderful sound..

Ummmmmmm. Yummy! Nothing like a set of 7" straights roaring.

As a four-stroke internal combustion engine, each piston in a diesel normally moves up and down twice in each cycle. The process begins when the fuel and air valves are closed and the piston moves upward. This compresses the air in the cylinder to as much as 25 times atmospheric pressure. This is much higher compression than a gasoline engine (typically ten times atmospheric pressure) and results in the air getting very hot. At this time fuel is sprayed into the superheated air which immediately begins burning. The second stroke, the power stroke, is the downward movement of the piston as fuel burns. The third stroke is an upward movement with the exhaust valve open to clear out the combustion products while the fourth stroke refills the cylinder with air.

The Jake brake completely changes all this, redefining what the valves do as each piston moves up and down. With the fuel flow terminated, the upward moving first stroke still compresses the air to very high pressure. As we said above, this transfers mechanical energy into heat as the air becomes highly compressed. If nothing else were done, most of this energy would be recovered, except for frictional losses, as the cylinder moved back down and the compressed air expanded. The Jake brake, however, opens the exhaust valve just as the air reaches maximum compression, dumping all of that energy in an almost instantaneous explosive release. The result is a very effective slowing of the vehicle as mechanical energy is converted to heat and then dumped. The Jake brake effectively transforms the internal combustion engine into an air compressor.

[Malaki86]

I had the elbow just below the muffler fall off (ya, it fell off) on my last local truck. Mind you, it was a day cab, with the exhaust literally 6 feet from me. Also, no A/C, so the windows had to stay down.

You want to talk about loud? I couldn't hear anything for 2 days after I drove that thing 40 miles with the missing elbow.

[Jackrabbit379]

I had the elbow just below the muffler fall off (ya, it fell off) on my last local truck. Mind you, it was a day cab, with the exhaust literally 6 feet from me. Also, no A/C, so the windows had to stay down.

You want to talk about loud? I couldn't hear anything for 2 days after I drove that thing 40 miles with the missing elbow.

Cool! 8)

[shyykatt]

When my hubby comes home (which is usually late @ night of course) I have him hit the jakes just for me
(we also happen to live on a lake/on the corner and the road curves a bit- so I can tell when he's coming coz I can hear him just before he starts coming around the lake; yeah, its not a huge lake).

[Roco]

Everyone Jake Brake makes it safer'
Roco 8)

[Ardmore Farms Forever]

What is a "Jake Break"? Well you have been given the technical answers.......here's another point-of-view.

A "Jake Break" is something that should be taken OUT of some trucks because the driver is too stupid, self-centered or have lack of respect for other drivers to even have one..........there is nothing worse than trying to sleep late at night or real early in the morning at a truck stop and here comes the LOCAL "Billy Big Rig" cruising thru the parking lot with his loud azz "JB" on...........WAWAWAWAWAWA", sort of like, "Everyone look at me, I'm effin cool."...and wakes everyone trying to sleep up.

Seriously, JB's are a God send if you run the mountains and hilly terrain unfortunately, the can and will malfunction occasionally, many drivers have become to dependent on them and have no idea what to do, if one malfunctions while going down a steep grade....................I actually use mine for braking even while running thru major cities on the Interstate, but turn it off when in 5:00 PM traffic because there really isn't any need.......yes, I'd argue with you if I could, I AM a conscientious truck driver, always thinking of the other people I share the road with, always spreading "goodwill" in the name of Professional Truckers..........please, no need to thank me, this is what I do.

[shyykatt]

...JB's are also useful when there is a 4-wheeler in front of you talkin' on their cell and not DRIVING... then they cannot hear!

[Adam9315]

When my hubby comes home (which is usually late @ night of course) I have him hit the jakes just for me
(we also happen to live on a lake/on the corner and the road curves a bit- so I can tell when he's coming coz I can hear him just before he starts coming around the lake; yeah, its not a huge lake).

Yeah, you like him to warn you so you can hide your boyfriend before he gets home. :twisted:

[shyykatt]

Ha ha....thats what he says too (have you two been talkin' or something?)


No cheatin' for me- I'm a good girl. (and I suck @ lying)

[stevedb28]

Ha ha....thats what he says too (have you two been talkin' or something?)


No cheatin' for me- I'm a good girl. (and I suck @ lying)

yes you do

[shyykatt]

oh brother...... :?
you guyz n' your demented imaginations- don't you have a truck to drive or something?

[stevedb28]

ill jake by the lake

[shyykatt]

you just drive 'round the lake and keep on drivin'........

:shock: