Transmission question

powderman426 wrote:
Its Cummin's:B

Maybe the "Cummings" is a Chinese knock-off? :R

As long as we're being picky...you probably have an exhaust brake with that engine, not an engine brake...big difference...and yes, it's all done with electronics..that's why it can be programmed to shift to a different gear....Dennis

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.

Mine is set up same as yours. Pretty much standard from what I can find.

It's a good setting.

No 'g', and electronics.

The transmission is programmed with a 2nd gear pre-select.

NO, it does not immediately go to second gear if you are at highway speed. It downshifts one gear at a time as soon as it will not over-speed the engine in the next lower gear until it reaches 2nd.

Kind of like when you are at a stop light and it says "6". It means when condition are right it will upshift to 6th, not that you are in 6th gear at the stop light.

BTW, you can have an Allison dealer re-program the ECM to any pre-select gear you want.

Its Cummin's:B