Mountain grades

Discussion in 'Questions From New Drivers' started by Bigowl, Dec 11, 2009.

  1. Bigowl

    Bigowl Light Load Member

    Nov 25, 2009
    Dallas, Texas
    Could a experience trucker tell me what was the steepest longest interstate mountain grade you have ever crossed and how did you learn to do it?
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  3. TripleSix

    TripleSix God of Roads

    Apr 10, 2009
    Copied in Hell
    The steepest grade will rarely be the longest grade.

    Before starting the downgrade, you will see a sign telling you the pitch of the grade and how many miles long it is. How to descend a grade depends on the truck, its weight, its gearing, and the weather. My rule of thumb is, if I kick the jack on and the jake cannot slow down the rpms( not maintain...slow it down), then I am in the wrong gear. For the non jake crowd: If you stab your brakes and dont drop 5 mph in under 3 seconds, youre going too fast

    Yea, you hear about Donner and Vail, but I smell more brakes burning coming off 26 westbound from North Carolina to Tennessee. It is a long ### descend. Or eastbound 70 heading towards Green River,UT. Not very steep but goes on for miles! Or that big mess on Interstate 8 between San Diego and Yuma (that sucka is steeeeeeeeeeeeep AND long on the eastbound side!)

    Foul weather? I'm crawlin. Lowest gear on the high side of the tranny.
  4. TripleSix

    TripleSix God of Roads

    Apr 10, 2009
    Copied in Hell
    I forgot to mention:

    A 4% grade, I wouldnt worry about. A 5% grade I wouldnt worry about on a straight road. 6% would depend on how long it is and how straight the road is, and how heavy I am. 8%, FULL CAUTION, doesnt matter how short it is, youre not going to be able to stop. 10% or more, I would come to a complete halt before the decent to start off in granny or first. Better be'll pop your motor if your brakes fail cuz a jake wont hold.
  5. JimTheHut

    JimTheHut Road Train Member

    Sep 26, 2009
    Central Ohio-Go Bucks!
    Is it true that you can not downshift once you start down the grade? That is what the CDL manual said.

    Bigowl Thanks this.
  6. TripleSix

    TripleSix God of Roads

    Apr 10, 2009
    Copied in Hell
    No, you can downshift. But you will burn your brakes up trying to slow down that much, AND if you miss that shift and panic, you have a Georgia Overdrive. Chances of surviving a Georgia Overdrive unscathed arent good. Even if you upshift and go into a higher gear, you will be going faster than you wanted and have a good chance of burning your brakes out before you reach the bottom. So to be safe, DO NOT DOWNSHIFT!

    I survived a Georgia Overdrive...

    my underwear didnt.
  7. GasHauler

    GasHauler Master FMCSA Interpreter

    Oct 23, 2005
    They say that the interstates can not go over 6%. But I don't believe it. I think I70 going into Denver should get your attention and then the I68 in WV and MD can be surprising too. Baker grade (I15 in CA) is a long downgrade and you have to watch for buses which loose their brakes all the time going north into NV. But any grade can be traveled safely if you just follow a few sound rules. Keep it slow so you can stop in an emergency if you come up on a accident or rock fall. You'll want your brakes to be cool enough to get the maximum braking if needed. I believe alot of drivers don't do this thinking it's clear to roll and they don't worry about their speed.

    Forget the old saying go down the grade in the same gear you came up in. The down side may be steeper plus todays engines are more powerful and can pull a grade better when this rule came out. It's always smart to stop at the top of the grade and check your brakes before you head down. Keep it slow enough to where you're not using you brakes so much. Roll your window down a crack so you can smell. At night watch in the brake lights if you see smoke. If you start to use too much air to slow then you're heading for real trouble. Slow it way down but do not stop. You don't want to stop because you want the air to cool the brakes. If you stop you may have a fire then all you can do is unhook your trailer and watch it burn.

    The best way to come down a grade is to use the engine brake and stay off the foot brake. If you don't have an engine brake then what I do is start in a low gear about a gear that runs the truck around 30mph when loaded let it drift to 35mph aplly brakes to slow to 25mph and then let if drift again. I've come down many grades with heavy loads up around 100,000lbs and haven't had any problems this way. But of course with the heavy loads I use 25mph. The engine brake is the best. I also think if you're not use to going down the grades stay below 35mph and you'll do fine as long as you don't ride the brakes. just always remember the emergency stop you might have to make.
  8. striker

    striker Road Train Member

    Aug 8, 2009
    Denver, Co
    Gashauler, interstates can't exceed 7% grade, I-70 through Colorado is 6% and 7% over Vail, Eisenhower, Genesse, and Floyd. I think this might also apply to some of the US designated 2 lanes, but if it does, then someone needs to refigure Monarch, Wolf Creek, and a few others.

    You know, when I was going through driving school, we had a week of road time, since I live in Colo. and went to school in Colo. I had a leg up. But, that said, there were 4 of us to a truck, 3 students and an instructor. We went up I-70 to the top of Genesse, made the turn and came down with the instructor behind the wheel. He showed us what and how to do it. When we got to the bottom, he tossed one of us behind the wheel, told us to get back to the top, and safely get back to the bottom. He critiqued everything we did. But, most importantly, he made us keep our speed at or below the posted limit, jakes on high setting, and very little use of the bakes, and keep the gears in 6th or lower.

    The biggest thing to keep in mind is every truck is different, every load is different. I have a co-worker who thinks nothing of smoking his brakes coming off the mtn., me, the last thing I want to do is smoke my brakes. 1. smoking brakes is a sure sign to the cops that you are/were speeding, 2. smoking brakes sends a bad message to the motoring public about your skills, 3. smoking brakes sends a message to the cops that maybe something isn't adjusted correctly.

    One final thing, if you've ever heard the song Wolf Creek Pass by CW McCall, it's about right. That pass will chew you up and spit you out if you get too ####y with it. If you go over the side, it's a long way down and there are only two runaway truck ramps on it, and they are near the top.
    Last edited: Dec 12, 2009
  9. RenegadeTrucker

    RenegadeTrucker Road Train Member

    Dec 25, 2009
    What I was taught is that you try 1 full gear lower going down the hill than you climbed it in.

    then adjust accoridingly

    BTW, the factory brakes on my truck lasted until 700K It is because I relied on my jake, and not the pedal in the middle.

    If I had to apply the brakes more than once or so in a minute id drop a gear.
  10. Working Class Patriot

    Working Class Patriot Road Train Member

    Jan 17, 2008
    Wherever and Whenever...
    There's an 11% grade about mile long from Las vegas, NM to Trujillo, NM.....

    No big deal.....just drop it down and take your time......
  11. A512

    A512 Light Load Member

    Dec 16, 2009
    If you think you are in the wrong gear as you are hitting the brakes waay too often

    then you should be..while you're still ahead hit them about 2 or 3 good times til you

    get er backed down to1k and get er in gear before your too far in.? am i right/?

    Steepest grade ive went up was some road that cut in between 77/79. was on that

    thing for 40 miles. was goin up hills in 3rd gear.

    Basically the way I knew I was in the

    wrong gear is the amount of time between brake applications.
    Last edited: Dec 26, 2009
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