Exhaust or jake brake or neither?
How do I know if I have a jake brake, an exhaust brake or is it possible that we don't have either of these? We have a 2001 holiday rambler imperial with an Allison 3000 transmission. Am extremely...
Forum Discussion
BarbaraOK wrote:
Most pacbrakes do not engage until you are down around 40 mph and the transmission in 4th gear - at least that is for us. Start going down by slowing down to 40 or less (depending upon how step the down side is - - use the signs as an indication of how slow you need to be) and engage the brake and take your foot of the brake and let her walk down.
Barb
Barb,
You need to verify, as an exhaust brake not engaging until you are slowed to 40 MPH is NOT CORRECT.
The instant you turn on the exhaust brake and close the throttle, you should see the transmission shift pad change from "6" to your pre-select gear (usually 2 of 4) AND, repeat AND the exhaust brake close. No, it doesn't have as much effect at higher speeds, because it takes more braking HP to go from 60 to 50 than, say, 40 to 30.
As you continue to slow, the transmission will continue to downshift toward the pre-select gear and the exhaust brake butterfly stay closed until you are down in 2nd gear, at which time the exhaust brake turns off, as the engine won't idle with the exhaust closed.
