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New engine brake question

Yahoo Message Number: 13175
Can someone please explain the difference, between a Pac Brake and a Jake Brake? Does CC use both types on its coaches? If so, which coaches come with which type? Thanks for the info.

Tony Ferrara

'04 Inspire 51172

Re: New engine brake question

Reply #1 –
Yahoo Message Number: 13177
Quote from: Tony Ferrara\[br\
]
Can someone please explain the difference, between a Pac Brake and
a Jake Brake? Does CC use both types on its coaches? If so, which coaches come with which type? Thanks for the info.

Quote
Tony Ferrara
'04 Inspire 51172
This is a good way for me to be certain my understanding is correct: The Pac Brake is an exhaust/transmission brake and the Jake Brake is an Engine/transmission brake. The Jake brake is better and more expensive which is why the Inspire has a Pac Brake...to reduce the cost of building the coach. I am still much happier with a Pac Brake than without. VBG

Carol

'04 Inspire 51046

Re: New engine brake question

Reply #2 –
Yahoo Message Number: 13200
Carol,

The Pac Brake, an external device, restricts the exhaust flow with a butterfly valve to create resistance. A Jake Brake is an integral part of the engine that holds the exhaust valves open creating huge amounts of back pressure and kind of turns the engine into an air compressor. The transmissions job is just to keep the RPM's up allowing both systems to operate at peak performance.

Our big trucks don't use any exhaust brake, there whimpy, all are jake brakes. Most big trucks are not automatic, allowing the driver to select any gear that keeps his speed in check. An 80,000 lb rig on a steep grade will use the jake, but will have to be supplemented with brakes as well.

Hope this helps in understanding the two systems. The 04 Allure I just bought has both I think, 1 switch postition for the exhaust and the other for the jake. If I'm wrong, someone can clearify that, I've only had it a week.
Tom

04 Allure 30979

Re: New engine brake question

Reply #3 –
Yahoo Message Number: 13205
Tom, you have an engine, or Jake brake only on your ISL370. The high position actuates the mechanicals on twice as many cyls as does the low position.

George Sanders in Birmingham, AL
Allure 31038

Quote from: truk4u2003
Carol,

The Pac Brake, an external device, restricts the exhaust flow with

a

Quote
butterfly valve to create resistance. A Jake Brake is an integral > part of the engine that holds the exhaust valves open creating huge > amounts of back pressure and kind of turns the engine into an air > compressor. The transmissions job is just to keep the RPM's up > allowing both systems to operate at peak performance.

Our big trucks don't use any exhaust brake, there whimpy, all are > jake brakes. Most big trucks are not automatic, allowing the driver > to select any gear that keeps his speed in check. An 80,000 lb rig > on a steep grade will use the jake, but will have to be

supplemented

Quote
with brakes as well.

Hope this helps in understanding the two systems. The 04 Allure I > just bought has both I think, 1 switch postition for the exhaust

and
George in Birmingham
2003 Magna 6298

Re: New engine brake question

Reply #4 –
Yahoo Message Number: 13207
Thanks, Tom

I wasn't too far off...esp about the Jake brake being stronger and better than the Pac brake. From reading the brochures on the Allure, it appeared that the Jake brake was an option to replace the Pac brake. I could be remembering incorrectly.

Hope your week with your Allure has been fun - and that the rest of the time you have it is also. 8-)

Carol

Quote
Carol,

The Pac Brake, an external device, restricts the exhaust flow with

a

Quote
butterfly valve to create resistance. A Jake Brake is an integral > part of the engine that holds the exhaust valves open creating huge > amounts of back pressure and kind of turns the engine into an air > compressor. The transmissions job is just to keep the RPM's up > allowing both systems to operate at peak performance.

Our big trucks don't use any exhaust brake, there whimpy, all are > jake brakes. Most big trucks are not automatic, allowing the driver > to select any gear that keeps his speed in check. An 80,000 lb rig > on a steep grade will use the jake, but will have to be

supplemented

Quote
with brakes as well.

Hope this helps in understanding the two systems. The 04 Allure I > just bought has both I think, 1 switch postition for the exhaust

and

Re: New engine brake question

Reply #5 –
Yahoo Message Number: 13212
[Country-Coach-Owners] Re: New engine brake question Tom,

you say holds the exhaust valves open. Don't you mean closed? If open it would vent the cylinders. If closed it would increase the pressure. Or am I missing something here. Being a gas engine owner, I am trying to absorb and digest all the information i can about the diesel rigs. Our next will be a diesel.

Dave Fagen
1989 32' SE

St. Petersburg, FL
At 01:26 +0000 12/1/04, truk4u2003 wrote:

Re: New engine brake question

Reply #6 –
Yahoo Message Number: 13218
Tom, I think you'll find you have a two stage Jake brake, one offering more braking power than the other. I always use the stronger of the two which is the forward down position of the rocker switch.

Walt Rothermel
03Allure30811

Re: New engine brake question

Reply #7 –
Yahoo Message Number: 13219
Hi Dave,

Maybe this will explain it a little better:

The jake brake slightly opens the exhaust valves when the piston is near top dead center (where ignition normally occurs). On the upstroke, the piston compresses the air in the cylinder to 1/15th its original volume. This creates a lot of drag on the engine. The Jacobs Engine Brake then releases the compressed air, and the energy stored in it, before it can push back on the piston during the downstroke. In addition, releasing the compression prevents any fuel in the cylinder from igniting. (Remember, diesels don't have spark plugs like gasoline engines - they rely on compression alone to ignite the fuel.) So, you've got drag on the upstroke, no power on the downstroke.

Cheers...
Tom

04 Allure 30979

Quote from: Dave Fagen \[br\
]
Tom,

you say holds the exhaust valves open. Don't you mean closed? If > open it would vent the cylinders. If closed it would increase the > pressure. Or am I missing something here. Being a gas engine

owner,

Quote
I am trying to absorb and digest all the information i can about

the

Quote
diesel rigs. Our next will be a diesel.

Dave Fagen
1989 32' SE

St. Petersburg, FL

At 01:26 +0000 12/1/04, truk4u2003 wrote: > >Carol,

>The Pac Brake, an external device, restricts the exhaust flow

with a

Quote
butterfly valve to create resistance. A Jake Brake is an integral > >part of the engine that holds the exhaust valves open creating

huge

Re: New engine brake question

Reply #8 –
Yahoo Message Number: 13220
Thanks George,

Thought I saw a PacBrake hanging up there by the turbo when I serviced it. You would think CC would be a little more detail oriented in the Manual about the two positions. All it says is you have a low and high, but doesn't specify position. Oh well, it works great..
Tom

04 Allure 30979

Re: New engine brake question

Reply #9 –
Yahoo Message Number: 13222
Tom,

You are correct on how the Jake brake works. However, you neglect to mention that on the way down after the compressed air has been released, the piston pulls a vacuum, which probably provides the majority of the braking action.

Per 5259 Affinity

--- truk4u2003 truk4u@...> wrote: