was driving over vail pass lastnight empty.

Btw....The "JIT's"....I don't do them in Winter....Especially running Vail....There is no way to predict what can happen.....

And it just isn't Vail that causes problems....Glenwood Canyon can get just as bad as Vail if not worse at night....I have been delayed a time or two because Glenwood was shutdown due to accidents....

 

Everyone with a no jake reply needs to get their head out of the text book response, and look at the reality/physics, his trailer was coming around! <---what causes that?
Answer: A lock up of trailer axles, NOT the drives, or steers. Not once did he mention a tractor knife, only a trailer knife.

Everyone needs to know their rigs, but in general you loose traction in order of weight (empty): Trailer, Drives, then Steers. And trailers will take longer to release brakes, so in effect your trailer will continue lockup and thus jackknife longer until wheels turn again. Engine braking whether it be downshift or jake is possibly more desirable because you keep all axles turning without any air spike. Depending on the mode of operation your rears are engauged with will determine its effect.

Normal operation: 1 drive hub powers the entire rig
Pwr diverter: (Engaged) 2 drive hubs (1 front, 1 rear)
Axle interlock: (Engaged) all drives have power
​

The opposite is true on deceleration, 1 drive braking vs. 3 turning... or 2 braking/2 turning or all 4 braking. Although 1,2, or 4 may loose traction on deceleration, they never stop spinning, and will help you keep control longer.

I'd like to hear anyone that argues this point?

 

Very well said........... As I said before, I will use an engine retarder any day before stepping on the service brake but.........in bad road conditions my finger is always on the switch or foot on the pedal to deactivate it at the slightest hint of wheel slippage. What also hasn't been mentioned here is that most engine brakes are three stage. I'll usually run it on low or medium on bad roads. One of the other posters even mentioned that the newer trucks will disable the jake when wheel slippage is detected.

 

Single cause fallacy. http://en.wikipedia.org/wiki/Fallacy_of_the_single_cause

It's all jackknifing.

Generally, but that isn't rig dependent, assuming similar configuration.
.

Depends, on many factors. If your steers and drives are turning free and the tandems aren't, but are still providing sufficient drag, the 2 components of the rig get into a state of "stretch", which is why trailer brakes are intended to engage first, and mountain drivers keep a close eye on those slack adjusters, winter or not.

Huh?

Your physics might be fine, but you seem in this instance to commit a casual oversimplification. You assume an environment of a vacuum with constant traction (/lack thereof) available to all (identical) tires, all the time, and perfectly straight alignment of the 2 components. Tandems are not necessarily parallel to the drives, probably usually aren't. Braking just the drive/s puts the 2 components of the rig into a state of "compression". The trailer might follow, it might not. If you're steers aren't parallel to the drives (turned L/R), however slightly, it can turn into a real mess. Assuming perfection in every regard, hitting a dry spot or pile of gravel can turn it into a real mess.

 

Actually, he's right. If the truck wasn't sliding but the trailer was the only possible cause is the trailer losing traction. If the truck loses traction but the trailer didn't is when you get your typical jack-knife due to the trailer pushing the rear of the truck. It IS basic physics.

 

If every rookie went out there with this attitude, we'd have a lot more accidents than we already do. Most drivers will not get 3 days in a row to drive with chains. It takes time on the road to get experience, which means you need to be able to stay on the road to get it.

I say exercise as much caution as desired until the necessary experience is gained to drive safely in adverse conditions.

 

Don't let a few blowhards keep you from asking questions. Everyone has a different learning curve and a different starting point.

 

Why does every thread like this turn into a pissing match on who's right and who's wrong?

 

I see nothing wrong with debating the points. However, making the OP feel like he should never ask questions is not right. If a driver doesn't know something, regardless of why, then we should welcome the questions. Even the best CDL schools can't teach everything.