Exhaust brake terminology

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Ron

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RV Roamer said:
Industrial Automatic (Telma dealer in my link above) says $5500-$6500, depending on the specific motorhome.? More expensive than a PAC Brake or similar turbo-exhaust-type brake, which is probably why we don't see many of them.? Competitive with Jake or other engine brake, though.
Sounds kinda priicey but probably not as expensive as upgrading to a Jake brake.
 

Smoky

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Any one know what kind of brakes are on the pusher I ordered?  Newmar Kountry Star KS3910 with 330 turbo Cummins.

The Beaver I looked at clearly labeled the switch PAC brake.  I think the KS is labeled exhaust brake, but cant remember.

On all the MHs I testy drove, the exhaust braking seemed rather subtle.  Is that actually the case?  It did not seem as noticeable as when I downshift a gasoline vehicle.

 

BernieD

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Smoky

The 330hp Cummins is only available with the exhaust brake, compression brake isn't offered on that series engine. PacBrake is a brand name for a particular company's exhaust brake model.

The effect of the exhaust brake is 2 staged; first is the transmission downshift (speed permitting) then the effect of the exhaust backup. A lot depends on the speed at which you are traveling when the brake is actuated. If you are at a good speed and both stages occur at the same time, you can get a significant effect.
 

Ron

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Smoky,

The exhaust break efficiency is dependent on engine RPMs at lower RPMs it provide much breaking.? That is why the transmissions are programed to preselect? 4th or even 2nd. Then the transimission will shift down as engine speed allows.? At 65 MPH the transmission will not shift down even though 4th or 2nd is preselected until a down shift will not over speed the engine.? As speed allows allows the transmission will continue to down **** to the preselected gear 4th or 2nd.
 
J

jscuzz

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Fixed what?? It still is recommending shitting.

Smokey:

That's why Allison says they designed the trans to prevent us dummies from hurting it or the engine. ::) ::)
 

fredethomas

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There are three kinds of engine operated brakes.  Jake is built into the valve system in the engine.  Very powerfull and very noisy. Then there is the exhaust brake - one is called a Jake also and the other is a Pac system.  They are butterfly vavles that close against the exhaust outflow putting a back pressure on the engine.  The third is a retarder and is installed in the Allison Transmission.  Very good but take a large radiator to disapate the heat. 

The exhaust brake CAN  be left on all the time but then when coasting it comes on a you lose "downhill momentem."  If in heavy traffic or where there are lots of stop lights - to me it is better to leave it on and just play the throttle to engage it or keep it open.

 
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