[CaptainGizmo]

I've spent WAY WAY WAY too many hours, phone calls, and head-banging on this topic to even try to remember!
When I had our Dutch Star, I discovered an issue with programming, only after getting "reprimanded" by so many who said I was not using the CC correctly.
I've been in California my whole life, and have driven so many mountain roads in the western states; 70 down from Breckenridge is a nice steep one, along with our constant playground through the Sierras, the Gravepine, and Devore pass. These all range from 6 to 9% on average, so I feel I've had a lot a "Jake" experience.

Ok, all that background said, I have a Cummins/Allison so mine's not the same programming, but the principles of the way they've been programmed still apply.

There are special settings in the computer that control how much "over" or "under" the set point, the CC will allow the rig to go before "doing something". Something CAN mean, accelerate/deaccelerate, Jake ON/OFF AND WHAT STAGE!! That's what the gotcha is!!

Cummins had to use a compter to find out that my Dutch Star wasn't activating the HIGH stage when in CC! This can really affect decceleration and Jake performance and is why lots of folks choose just to turn it off in the hills.

On our Newell, I really can't tolerate having the CC on going down grades much at all. Reason being, it holds the Jake off too long, and causes my speed to over-run way too much for my defensive feel.

I hope all this helps you. I really doubt you'll have to manually downshift your CAT, so long as you disengage your CC. But, my guess is, if you DO leave the CC engaged, you're not going to like it.

[Sea Note]

Thanks, everyone. I think my takeaway is to use the CC uphill as it will be smarter than me when selecting the proper throttle and gear combinations but disengage before cresting, drop a gear or three (or so) from the gear the CC had me in before cresting depending upon the approaching grade, make sure the jake is on/on high, and adjust from there.

I really appreciate the advice.

Best regards,

db

[hypoxia]

I don't think you will be using the CC at all in the big mountains.  They are twisty turney and speed is not your friend.  Truckers say the speed you are at when you crest the hill is the speed you shoot for going down.  My method of descent is to be slow enough using the Jake to rarely if ever touch the service brakes.    I do not want the service brakes to be warm in the event I need them when I come around a curve into an accident scene, rock slide or herd of elk.  I pass trucks going up and they pass me going down.  I look for the yellow speed advisory signs and go around curves at that speed or less.  When the furniture starts moving around I start hearing copilot noise.

The Cummins ISX 600 and Allison 4000 is the same combination I had in my last coach but the gearing and weight are different.  I find myself manually shifting the Newell more often on steep narrow switchback roads.  I spent a fair amount of time in 1st gear last summer on one road in the Rockies.  I was told that West Virginia is so twisty you can stick your hand out the window and hit yourself on the back of your head.  I found that to be true and couldn't use the CC because of it.

You'll figure it out quickly and although the Cat is different the concept is the same.  Everyone is giving good advice.

[Richard]

We all have opinions and slightly different experiences. I generally do not run the CC going up a significant climb for one reason. It pegs the fuel to try to maintain the speed. The impact of that is rising engine temperatures. Now, the cooling system takes care of that but I prefer to run at something less than WOT (wide open throttle) when climbing. I am just not that interested in trying to pass the struggling trucks.

I do pay close attention to the slow motion chess game with the trucks on a mountain climb. Manually controlling the throttle and monitoring the situation allows me to plan my passes or avoid rapid deceleration events when approaching a slower vehicle.

I think you are asking fantastic questions for a new driver of a weighty vehicle. It has been a very good discussion.

While we are on the topic. If you find that you are overheating on a long climb, drop to a lower gear, run the engine at a higher RPM, and back off WOT. This does two things. It reduces the fuel (heat source) going into the engine. It moves more air through the engine at the higher RPM. The air takes heat with it. Just mentioning it because it is a nice trick to have if you need it.

And one final thing. On my coach, the CC and the jake do not play well with one another in rolling terrain. At each downhill the jake will try to slow me down, cutting into the fuel mileage, only to throttle up to climb the next rise. But……while cruising the highway, I personally want all the brake I can get. So, many years ago, we developed a 20 buck modification to the Jake on off switch that allows three positions instead of on off. On triggered by accelerator, off, and on but triggered only when brakes are applied. I use the last position cruising the interstate to avoid the CC Jake tussle. I use the first position triggering off the accelerator when in the mountains so that I do not have to ride the brake to use the Jake. If any are interested in the modification, speak up and I will post some instructions.