A little winter adventure (Learning about traction for dummies)

So, as per usual for anything winter driving related I post, this isn't for the risk-averse.

Monarch Pass, just after lunch today. I knew weather was inbound, but the chain law wasn't up, and it was mostly full throttle going up on the mostly frozen slush common here. Visibility was the limiting factor, although I slipped a couple times on hidden runoff that had refroze, but nothing major. Caught the plow at the top, as a straight truck had clumped traffic putting on his chains. So off the south side we go!

To say traction changed would be understating it. Ended up running 5th ~1500rpm which was roughly 15mph. Any faster and the extra energy would start sliding tires. I was able to use the Jake, but only with the power divider locked. Except in corners, which is the point of all this verbiage.

Going around the corners, extra traction needed for the corner took away some of my linear traction, which meant 15mph was now too fast. So every corner was the same dance: off the Jake, onto the brakes, slow to 10-12 mph, be disconcerted as the drives and trailer slipped ever so slightly into the banked curve, leaving one with that "Why does it feel like my nose is too high in the corner?" feeling, off the brakes, onto the jake.

The lesson here? That small 3-5 mph speed reduction resulted in a 36% - 55% reduction in the braking traction needed to maintain speed, leaving some traction available for lateral forces.

This is the traction circle at play again. Maxing out avaliable traction in any one direction leaves no traction available in the other directions. So if I maintained 15mph into the curve, the added traction needed would overload the tires and they would start to slip. Slightly slowing gave me a bit of reserve traction to use for cornering.

And because I know it's coming: "Hammer, why not just use the brakes, the Jake will kill you!"

I find it far less taxing to use the Jake and wheelslip, and ultimately the chug when the ECM detects that wheelslip and briefly cuts the Jake, to serve as an early warning device. At those speeds and the light pressure required, one could easily drag the brakes all the way down. I just find it easier to let the ECM do its thing, and that is far easier to sense than an ABS activation, especially in such a low traction environment.

Incoming gripe #2: "You're going to die locking the power divider on slick downhills!"

I'm firmly with you on "unlocked" on Jake as standard practice. It's much more stable to lose 25% instead of 50% of your traction when a tire locks up unexpectedly. But in this case, it was already established that traction had largely left the building, and the Jake needed the power divider in to avoid instantly locking up one corner.

And lastly, the safety department answer: "Just SLOW DOWN!"

Negative, Ghost Rider! Sliding down the banking was already an issue that slowing further would only exacerbate. Go to slow, and the pull to center uses all of your traction and will introduce you to the sound of metal and rock (or timber) becoming well acquainted. See any banked flyover ramp on any icy Texas day to see this illustrated in person. It's actually quite amusing to watch as long as it's not you!

And there you go, use it or lose it, be safe out there!

 

And even checking cameras can't always answer road condition questions. I mean, I'm not blind, I could see it snowing up high all the way across South Park. No chain laws were up when I committed, and while they visibly looked identical to Monarch, Cerro & Blue Mesa were fine traction-wise. As you well know, some days you just get surprised, you expect a mild annoyance and get dropped into a skills test!

 

While I understand the reluctance to have their trucks out in it (and money they save buying all positions for drives) it does you a disservice in that you never get the chance to learn the skillset. But that's more common then not, anymore. I've often wondered if they eliminate more accidents by parking y'all early, or do they have more because so many drivers have zero clue when they go get caught out in it?

Above my pay grade!