Slick roads 101

Wrong. Look up what a differential is, what it does, and how it works. That is all the power divider is doing...locking up an otherwise open differential.

 

The other guy is correct. This can easily be demonstrated on ice. With nothing locked, one dual will spin on one axle only. Lock in the power divider and one dual on each axle will spin. If your truck is equipped, then lock in what's often labeled the "dual axle cross-lock". That's what you're talking about, it locks the differentials. Once you lock that in, all 4 will spin. You can safely drive down the road and around corners with the power divider locked since the differentials are still free. Try that with the differentials locked and you'll have a hard time turning. Most trucks aren't equipped with locking differentials, and for good reason. Way too easy to screw up bad with them.

 

Wow..just wow..jack up both rear ends so they aren't touching the ground..and get in the truck..start it up put it in gear..and the only set of tire that will spin from the engine is one of the REAR Rear ends..one side..put in the power divider and one set of tires on the opposite side from the spinning rear tires will spin on the front drivers along with the rear drivers...then if you have lockers and put BOTH of them on..all four sets of tandems will spin..now I'm not talking about the slow spin that you get from the gears moving inside the 3rd member when they are not engaged washing fluid that will get the other wheels to slowly spin...put you hand on them..they will stop with your truck in gear and one set will not stop as they are in gear..those other wheels have no torque or power to them..until you put the power divider on and then you HAVE two sets of tires that have power and torque put to them. And that's IT. Unless you have full lockers..most big companies don't have those as they cost money,weight and front want the inexperienced driver using them improperly..some are even taking out the closer drividers..they got tired of drivers tearing them up

 

Winter roads in MN and WI.

 

Apparently you don't have a clue either. There are 3 different differentials on a 6x4 truck. There is the center differential on the front axle, which allows the left and right side tires to spin at different speeds (as in driving around a corner). There is the center differential on the rear drive axle, which does the same thing as the one on the front drive axle. Then you have the inter-axle differential, which allows the front axle to spin at a different speed than the rear axle, such as when tires aren't exactly matched up and some are more worn than others. On most trucks, all 3 differentials are what they call "open", which basically means that torque applied to all 4 corners of the drive system is limited to the amount of torque required to break traction on the wheel that has the LEAST amount of traction. The truck doesn't care if that tire is the front left, front right, rear right, or rear left. If it has the least available traction, when it breaks loose, NO additional torque is sent to ANY other wheel end...so you sit there spinning that one wheel set.

When you lock in the power divider, ALL you are doing is locking the inter-axle differential so there will be NO difference in speed between the front and rear drive axle. The center differentials are STILL open on most road trucks, so the center differentials are still going to limit your ability to move. Yes, now 1 wheel end on each axle will turn, but again, that will be determined by the wheel end on each axle with the LEAST traction available to it. Once the tires break free, NO additional torque will be sent to the non-spinning tires, so you sit there spinning 1 side of each axle.

I haven't brought up fully locking rears (all 3 differentials lock up) because most trucks don't have them, and the trucks that DO have them aren't sitting there stopped stuck with 1 or 2 wheel ends spinning. I haven't brought up Mack rears, either, which are a different animal altogether.

 

With all 4 corners jacked up, all 4 corners will spin because very little torque is required to spin any of them. The only resistance needing to be overcome is whatever drag is caused by the bearings as well as what is necessary to get the wheels turning. If you put your hand on one of the spinning wheels, you can stop that wheel because it is only receiving the torque necessary to spin the wheel with the least resistance...which is pretty much zero because you have everything jacked up off the ground.

Engage the power divider. All 4 will STILL spin, because it STILL requires about the same amount of torque to spin each wheel. You can STILL stop a wheel on either axle with your hand, because the center differentials are still open...you've only locked the inter-axle differential.

 

If one is on a slick road then they had best understand what they can and can't do with ALL of the equipment on their truck..and what it does and what one can't do.

 

wsyrob,

I'm glad that you didn't delete the posts.
I actually learned one specific/vital aspect from this 'exchange', that long ago I knew correctly, but over time 'slipped from my mind' and now glad it is corrected.