Transmission question
2001 holiday rambler DP, 360 Cummings. When using the engine brake, what causes transmission to go in second gear?
Forum Discussion
The Allison "talks" to the engine, and they're similar in operation no matter if it's a Cat or Cummins.
My 3000 series has two digits, one for what it's doing, and the other for what it's planning. Newer Allison panels have only the single "what it's planning" digit, which really is kind of stupid because you can't tell what it's really doing other than seat of the pants feel. Greenleaf (monitor systems) adds that missing digit back in their upgraded monitor panel.
As soon as the EB switch is flipped, the 2nd digit shows 2. That's what it's headed for when you're slowing down, and on a freeway exit ramp etc., that's what it will do. If you're doing 60 MPH on an 8% grade, it may never get below 5 unless you tap the service brakes to drop the speed, then after 4, it'll start slowing down more. With two digits, you can see what she's doing, (5, 4, 3, 2 as you slow) but with one, all you can see is '2' only.
In my coach's case, the EB drops out at 12 MPH and/or while it's in 2nd. It is programmable, but I'd leave it, as it does work well as it is. I have an upgraded PXRB Pac brake, which is about double the slow-down rate from stock. I can drop to that 12 MPH by hitting the EB switch about 1/3 of the way down an exit ramp, and be all but stopped at the end of the ramp.
My 3000 series has two digits, one for what it's doing, and the other for what it's planning. Newer Allison panels have only the single "what it's planning" digit, which really is kind of stupid because you can't tell what it's really doing other than seat of the pants feel. Greenleaf (monitor systems) adds that missing digit back in their upgraded monitor panel.
As soon as the EB switch is flipped, the 2nd digit shows 2. That's what it's headed for when you're slowing down, and on a freeway exit ramp etc., that's what it will do. If you're doing 60 MPH on an 8% grade, it may never get below 5 unless you tap the service brakes to drop the speed, then after 4, it'll start slowing down more. With two digits, you can see what she's doing, (5, 4, 3, 2 as you slow) but with one, all you can see is '2' only.
In my coach's case, the EB drops out at 12 MPH and/or while it's in 2nd. It is programmable, but I'd leave it, as it does work well as it is. I have an upgraded PXRB Pac brake, which is about double the slow-down rate from stock. I can drop to that 12 MPH by hitting the EB switch about 1/3 of the way down an exit ramp, and be all but stopped at the end of the ramp.
