Down hill grade on slick hyways

Jakes with the power divider locked in is never a good thing, even on just rain slicked roads, much less ice and snow.

 

Oh good old Wolf Creek. That's the one that separated the men from the boys.

 

would you care to elaborate?

Jakes (engine brake), is a system of reducing the exhaust gas flow creating back pressure (increased compression) on the pistons.

I need someone to tell me (precisely) how additional compression is directly effecting the drive line(s). On the other hand...Jakes (engine braking) and application of brakes (foot or Johnson Bar) will effect forward momentum, which on slick/slippery surfaces, will/can greatly effect the trailer breaking traction and the potential when this happens can/will cause the trailer to come around. Another example of "path of least resistance".

 

RE engine braking and locked differential (DOWNhill operation): I don't think it's so much about wether or not an engine brake is engaged as it is how a locked differential can make a truck potentially "bounce" and act squirrilly. Uphill or downhill, jake or no jake .. a hair pin turn, snow-pack, and a locked differential can cause a "weird occurrence" at a time when you least want one. I think going relatively straight, up or down, differential lock usage has no ill effects either way, but the diff lock can cause issues in tight turns and the jake can cause unexpected issues going down if it's slick enough and you don't have a lot of weight on the drives. So, what I'm trying to say is both need to be used wisely on slick roads (if at all) ... and insofar as going DOWN hill, I see a locked diff as a potential cause for problems more in switchback turns than anything.

 

Check out all the black rubber marks and "battle scars" on the concrete guard rails at the sharpest hair-pin turn about half way down. Not sure how much of that is "snow caused" and how much was "speed caused" but I'm fairly certain that grade has caused a lot of drivers to rethink their lack of respect for that extra 1% additional decline vs a normal 6% decline (7% for a good portion and perhaps a "bit" more in a few places)

That hill can cause problems for empty and lighter drivers too, if they are not careful.

 

The old setup of traction (power) to the rear without power divider engaged (rear left was norm) and rear left with forward right when P/D engaged has been changed. The common power is rear left and forward right have continual power without P/D engaged, and all four have power when engaged. the spider gears have been reformatted to the new "theory" as well. When a truck has chains applied, the driver needs to engage the P/D to maintain equal power/traction with the different power/torque application we run on these newer trucks (2005 was the change so I'm told).

otter someone has been feeding you a load of that stuff that comes out out the back of a male bovine. AKA BS having trained and worked as a truck mechanic for a number of years.
when the diffs are unlocked in an equal traction situation all wheels deliver roughly equal torque to the ground.
when the diffs are unlocked in an unequal traction scenario, like 2 wheels on ice those two wheels will spin, the torque follows the path of least resistance. there is a slight tendency if all four are on ice for a certain pair to be the first to spin. it is only a slight tendency, perhaps related to the torque of the drifeshaft increasing the traction on one side a tiny bit.
the jakes with the pdl isn't a huge issue for me, the jakes with the quads locked isn't a huge issue for me IN SOME PLACES(because I drive winter ice roads every winter), but downhill there is nothing to be gained in traction by running them locked, but a lot to be lost in terms of steering control.should the jakes cause a wheel to lockup on ice going downhill its much better that only 1 locks up than all 4. the other school of thought is that the 2 or 3 wheels with traction will keep that 1 wheel turning, however when that goes bad it goes VERY bad. one thing to keep right at the front of your brain if traction may be an issue(while downhill with jakes) is that the fastest way to straighten things out is to put your foot down HARD on the righthandside. then turn off the jakes, little bit of spike, then back to normal programming. big thing is looking ahead anticipating what could possibly happen, and having a plan to deal with it before it happens. if you have thought about what you need to do to drive your way out of a mess before you are in the middle of the fecal matter, you are better off

 

those are all speed related, the bottom feeders are trying to find a way to get to the bottom faster. Check out the dirt lot next to the tow company on the E. side of Pagosa, there is always 4 or 5 carcasses or remains in there. When they were rebuilding the lower ramp, even with the limit at 15 mph for the curve, they still averaged one roll over a week for 5 months, and 4 of those were SWIFT

 

yep, anytime I'm chained my P/D is on, but I also have auto traction control so it depends on the road conditions as well

 

I respect that mountain, as I do all, even Monteagle (which I don't think is that bad) but that one I give that much more to. Ive seen a lot of guys almost lose it there, ones with a hell of a lot more time out here than me. It's just like Cabbage or any other windy pass. You never know when she'll get out from under you. The old saying: you can go down a hill a million times too slow and only once too fast. Never have truer words been spoken.

 

Ok guys Good thread. here it comes. BUT dont forget the simple things! for all you NEWBIES (dont mean that in a bad way) we have all been there.
Remeber your FM (fleet manager) is not in the truck! your driving it make the right choice about whether to stop or drive on. Dont worry about the SPEED JOKIES go as fast as you feel safe and still control the truck. Down hill be easy on the brakes especialy in curves and offramps. Remeber ice has NO friends! chains are a great tool but they dont make you bullet proof! dont be embarised to ask an older driver for some advice in the TS or on the CB (yea alot of us still use those things. Be wearry of the drive who tells you its just snow drive it! KEEP IT SAFE AND I HOPE THESE WORDS HELP YOU