Have about 7k miles on this coach driving out west, some hills, some BIG hills - 40' Monaco with 400 Cummins pulling about 5300# toad. Will soon be going from Knoxville through Asheville to South Carolina. Mountain driving - up and down - questions.
Up - do most just let the cruise do it? Do you manually downshift? Do you downshift BEFORE its really needed to gain the spurt?
Down - let exhaust break control? Exhaust AND downshift? Downshift manually early? If downshift - from 6 to ? (5 - 4 - x).
In the mountains I take the cruise off. I see a hill in front so I get up the speed. I will use my retarder on the downhill but manually move the gear selector when climbing and decending to the proper gear. If it a long down hill I will go down to 4 or even three depending onthe speed limit and turns. I have done that trip you are talking about and it is an easy trip so do not worry. DO not ride your breaks but rather stab them and you will be fine.
John
2001 42' Foretravel U320
2007 Bornfree 24 Painted
2001 Jeep Wrangler
2007 Burgman 650 Executive
Susie and Dolly (Cavalier King Charles Spaniels)
Dolly now in our hearts and thoughts 8-27-05
Doodle a Black and Tan Cavalier
Lolly a Ruby Cavalier
Same engine/trans... in that area, cruise off, econ mode off, and 5th will do about anything you want. Jake brake and toggle between hi/lo will do it coming down. You will love that setup after one trip through.
Happy Trails
06 Monaco Dynasty
99 Wrangler Toad
US Gear Tow Brake
FMCA 279843
novatz, I hope this isn't too much off topic. You asked about driving techniques but consider this: You may want to have a look at the Mountain Directory books that tell you where the steep grades are, how long they are, how steep (%) they are, whether the road is two lane, three lane, or four lane, if there are escape ramps, switchbacks, sharp curves, speed limits, etc. With this information, one can know ahead of time what a pass is like and make an informed decision about whether to go over or around.
Tom & Jan
Fulltimers since April '06 with 3 fur kids (George - mini Aussie, Archie - mini Poodle, Kitty - 20 yo blind cat)
1991 Beaver Contessa towing 2006 Subaru (4 down)
Started workamping Sept '07 - This isn't too bad. Think we'll do it some more.
We do that route quite often and have a similar rig with the ISC 350 and have no problems at all. The exhaust brake is very capable of maintaining descent speeds. The worst climb in that area is west bound I-26 at the NC/SC border but there is an additional truck lane on the up-hill side. Just be sure to watch the downhill grades as there are some well-marked sharp curves on both I-40 and I-26.
Roger & Denae
W4OHX
FMCA 334124
2004 Monaco Camelot 40PST
Lexus LX-470 Toad
Blue Ox/Brake Buddy
OP, please verify that you have an EXHAUST BRAKE not JAKE/ENGINE COMPRESSION BRAKE. The Cummins L engine could be ordered either way. But the only effect on driving techniques down a grade is that the Jake brake offers a high and low setting which gives you more flexibility. The Jake brake also gives more braking HP than an exhaust brake.
The correct way to descend any grade is to find a speed that keeps your speed IN EQUILIBRIUM (neither accelerating nor decelerating) WITHOUT USING THE SERVICE BRAKES.
We have descended double digit grades in the Green Mountains of Vermont without ever touching the service brakes. Yes, we were in second gear with the exhaust brake on. But we "roared" past a logging truck whose equilibrium speed was around 8 MPH.
And ALL heavy vehicle brakes will overheat if used to control speed. There is insufficient brake surface and insufficient heat dissipation to use them for anything more than application to allow you to slow enough to "down arrow" to a lower gear. NOTE: There is a wide range in "pre-select gears"-- that is the gear the transmission seeks when the brake is turned on. The Allison ECU can be programmed to select any gear 2-5, but 4 and 2 are most common. So your use of up/down arrows on deceleration and/or barely touching throttle to turn off exhaust brake is somewhat dependent on what gear your seeks.
That speed may be 50 mph or 10 mph depending on the grade. It may be in 5th gear or 2nd gear with the exhaust brake on. As a benchmark, your speed in a DP will be higher than a loaded 18 wheeler and lower than an empty one.
As far as climbing a grade, I suspect your Cummins owners manual (you might read it and post what IT says-- not just take our opinions) will suggest that the lowest RPM ABOVE PEAK TORQUE RPM that will allow you to climb a grade is the most economic way to do it. Sure, high RPM will get you there faster-- you decide how much a couple of MPH vs MPG is. And, if engine operating temps climb, gear down and bring RPM's UP. Producing the same HP/speed on grade with the water pump turning faster will lower engine operating temps.
And the driver has the most control by leaving the trans in Economy Mode and using the up and down arrows to select the "proper" gear. No transmission is any where near as smart as a good driver in mountains. BY DEFINITION, the transmission is REactive, not PROactive. It sees what happened several hundred yards BEHIND the coach, while a smart driver selects the correct gear for what is in FRONT of the coach. That is not to suggest that you can not leave it in DRIVE, but that will certainly be less efficient for MPG AND for MPH than a smart driver.
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