Community Forums

shamrock481 · 05-11-2012, 05:33 PM

So which one is better?

Barbaraok · 05-11-2012, 05:40 PM

We use both, down shift at the top of the pass, then come down in whatever gear we were in at the top going up. Sometimes we might even shift down one lower if the down side is steeper. Exhaust brake is on as we come down.

Barb

Mr_D · 05-11-2012, 05:49 PM

Quote:

Originally Posted by Barbaraok

We use both, down shift at the top of the pass, then come down in whatever gear we were in at the top going up. Sometimes we might even shift down one lower if the down side is steeper. Exhaust brake is on as we come down.

Barb

Uhh... Engine Brake is a "Jake brake" built into the engine, not available on engines below the Cummins ISL or CAT C-10 as I remember. Completely different than using the engine compression to slow down.

RustyJC · 05-11-2012, 05:51 PM

If one had a hypothetical choice, the engine brake would develop more retarding horsepower than an exhaust brake could. Unfortunately, those of us with "smaller" diesels have no choice but to go with an exhaust brake, which is much better than nothing.

Rusty

dashdriver · 05-11-2012, 08:25 PM

If you referring to the amount of braking each one will do, then the engine brake wins out. It is noisier however. Like others have said, you can't really choose between the two, that is done for you depending on what engine is installed in the rig. I guess you could choose to buy a MH with a big enough engine that it would have an engine brake. The nice thing about the engine brakes is they come with two-stages so you can control the amount of braking power to a certain degree.

shamrock481 · 05-11-2012, 11:16 PM

Thank You, Dashdriver, that's the explanation I was looking for. We're looking at a 2003 CC Allure with a 370 Cummins and it has an exhaust brake.
In the mountains out West, the exhaust brake and upshifting will be enough to keep us from overheating the service brakes?
I've driven cement, dump,fuel oil, block trucks in the 70's back east and they did not have exhaust or jake brakes.

distaff · 05-12-2012, 08:51 AM

Engine brake, Jake or Jacobs brake, engine retarder brake, or compression brake are all the same thing, and all change the valve timing in the engine to capture energy on the compression cycle and releases it out the exhaust valve. This prevents the "spring" effect of coasting where the engine compresses the air and then as it decompresses it returns most of the energy to the crank and eventually to the wheels. The braking effect available depends on the displacement of the engine, but it is typically between 300 and 450 hp.

An exhaust brake restricts air exiting the exhaust manifold. An exhaust brake typically provides between 100 and 150 hp of braking effect.

Engine brake is better, but it usually comes on a much more expensive engine and on a much heavier coach. I can point my coach down a 6% grade and ride the engine brake all the way down, on steeper grades I have to lower the speed I enter the grade to 45 or so, and then the engine brake will keep me there. I like it because I almost never touch my service brakes on a grade.

There is also a transmission brake available on some of the really high end Allison transmissions that is more powerful even than an engine brake, but I have only heard of it on a Prevost type chassis.

Barbaraok · 05-12-2012, 08:59 AM

Quote:

Originally Posted by shamrock481

Thank You, Dashdriver, that's the explanation I was looking for. We're looking at a 2003 CC Allure with a 370 Cummins and it has an exhaust brake.
In the mountains out West, the exhaust brake and upshifting will be enough to keep us from overheating the service brakes?
I've driven cement, dump,fuel oil, block trucks in the 70's back east and they did not have exhaust or jake brakes.

Yes, we climb up and down the Rockies and the Cascades all of the time. And I'm sorry I didn't understand what you were talking about before. On ours the transmission shifts into 4th when the exhaust brake engages. If we are in third when we get to the top of the pass, then Dave manually puts her in third, and we start down (or maybe second if it is really steep coming down) and only use the service brakes to slow as necessary - - really very little. And if you stick to interstate roads for the passes, then it is a piece of cake.

Barb

CD · 05-12-2012, 10:09 AM

Quote:

Originally Posted by distaff

Engine brake, Jake or Jacobs brake, engine retarder brake, or compression brake are all the same thing, and all change the valve timing in the engine to capture energy on the compression cycle and releases it out the exhaust valve. This prevents the "spring" effect of coasting where the engine compresses the air and then as it decompresses it returns most of the energy to the crank and eventually to the wheels. The braking effect available depends on the displacement of the engine, but it is typically between 300 and 450 hp.

An exhaust brake restricts air exiting the exhaust manifold. An exhaust brake typically provides between 100 and 150 hp of braking effect. .

You are right to a point. The Jacobs co. builds an exhaust brake that some call a Jacobs/Jake brake but is not an engine brake.

RustyJC · 05-12-2012, 10:15 AM

Quote:

Originally Posted by CD

You are right to a point. The Jacobs co. builds an exhaust brake that some call a Jacobs/Jake brake but is not an engine brake.

Jacobs puts a decal in the box that touts their exhaust brake as being a genuine "Jake Brake". I know that for a fact - I had one in my 2002 Dodge/Cummins with the decal in the back window. And, yes, I know that the colloquial use for the term Jake Brake traditionally refers to an engine brake.

Rusty

distaff · 05-12-2012, 07:00 PM

Quote:

Originally Posted by CD

You are right to a point. The Jacobs co. builds an exhaust brake that some call a Jacobs/Jake brake but is not an engine brake.

I've seen it on Dodge pickups, but when people say "Jacobs Brake" or "Jake Brake" it still pretty much means an engine retarder system. Too bad they are diminishing their brand.