Two questions I always forgot to ask that no one talks about

He's right. You can lock them on the fly. If you are rolling, and you need to lock them, all you have to do is let off the throttle completely. You can still be moving. Let off the throttle and engage the power divider.

This IS a common misconception. Was running up a slick hill in Montana. Had a truck come to a complete stop in the right hand lane. Drivers were screaming at him. He explained that he was stopping to lock in the power divider. The screaming got louder.

Next, some doorslammer is going to post about his company policy to never use the power divider, and how if you have an accident with the power divider engaged,its a preventable and you face termination.

EDIT: if you stop on the side of a hill where you need a power divider, you might as well go ahead and put the chains on.

 

I was told the power divide will automatically disengage at speeds greater than 45mph.

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Concrete Block Walls

What may look like a concrete wall from the outside might just be a concrete block wall. Also called Concrete Masonry Units (CMU) or cinder block because sometimes fly ash or furnace "cinders" are part of the aggregate and cement that make up the blocks. These blocks (sixteen inches long) are only about an inch and a quarter thick on each side as they are hollow, made up with a couple large holes. You might have seen videos of guys using karate to break these. When these blocks are laid up and mortared together they make a wall. Some of these voids are completely filled with grout (thin "cement") and steel reinforcing bars. Not all of them however, in the interests of economy.

In other words, what looks like concrete may be 8 inches of fairly solid material, or it may be a crust of brittle material only a little over an inch thick. Don't hit it very hard! Love taps only please.

By the way, the voids in the blocks create an hollow air space (running up and down) about 7 inches wide. This is probably a reason the rubber bumpers are much wider than that. It will also give you a clue that if you have to bump a wall slightly, do it square-on to distribute the force into the unseen ribs inside the wall. Especially, don't hit it with a sharp corner of a vehicle. You might be unlucky enough to hit it at the wrong spot and make a hole (up to about 4 inches wide). Be especially wary of newer buildings built with emmigrant contract labor.

 

How the drive axles work and what wheels pull when can be very confusing, and there are many common misconceptions. To simplify things and eliminate these misconceptions, all you need to do is memorize this simple statement that applies to a tandem axle truck with the power divider unlocked.

ALL WHEELS PULL UNTIL ONE WHEEL BREAKS TRACTION, THEN NONE OF THE WHEELS PULL UNTIL TRACTION IS REGAINED ON THE WHEEL SPINNING, THEN ALL WHEELS RESUME PULLING EQUALLY.

When you lock the interlock (power divider), one wheel on each axle will pull, no matter what, traction or not, you'll have at least two drive wheels (one on each axle) spinning and digging.

The rule on when to engage the power divider (or not to engage) is simple. Never engage under power or with a wheel spinning. This means to push in the clutch to break power to the driveline before engagement. Some prefer to just let off the throttle, however, the important thing is that there is no load on the driveline. This means do not engage when going down a grade with your foot off the throttle allowing the gear to slow you down (gearing down). This would be a form of driveline load, same effect to the interlock as under power engagement.

 

i see busted axles all the time. it's always the right front drive. which means thats the tire that does all the driving. when the divider is kicked in. the left rear drive comes into play.

now you've got 2 wheel drive instead of 1 wheel drive, realistically speaking.

i've driven dump trucks that also have a lock switch. meaning true 2 wheel drive or 4 wheel drive. both tires are locked in depending on if the diviider is locked in. front axle or both axles.

i've yet to see a OTR truck with a locker switch. only a divider switch. not to say they aren't out there.

 

And you can just keep thinking that, snowwy.

 

If these statements are fact, why does the axle manufacturer bother installing drive axles in two wheel positions that never pull?

Which leads me to the challenge of you pulling your left front and right rear drive axles before your next trip (since they aren't doing anything anyway) and let us know of the results of your trip.

 

Plenty of those in here, ain't there?

Priceless! Thanks for the laugh, TripleSix.

I'm not sure about the 45mph, or the power divider part, but some trucks with the full locks have an interlock with the range shift on the tranny; i.e. they disengage on the high side.

This is exactly right. Thank you, Bender!

All the time? Either you're around a bunch of seriously under-speced trucks or you work with a bunch yahoos But my money's on the third option.


Seriously guys, you can run with the power divider locked for hours, provided you're on a low traction surface. It's actually easier on the divider than running along with one wheel slipping all the time. And the divider is stronger locked, as it eliminates the differential, locking the two shafts together.

Back in the day, power dividers were a weak spot, but for a reason most drivers didn't understand. When only one wheel was spinning, the internals of the divider would rotate fast enough to fling the oil off and overheat, weakening the gears. It wasn't unusual for this not to show up until a hard pull at some later time.

And Nash? As pointed out, bumping buildings isn't a good idea; you may do it 255 times with no problems, and the 256th will byte you in rear.

 

I had A Mack dump truck , tandem , and the differential would fully lock. All 4 sets of tires driving. The caveat was not to drive in that mode and in no instance exceed 40 mph. Worked great off-road or if you got stuck. I have found the run-of-the-mill power divider pretty pitiful if you get stuck. The drives function " catty-corner "to one another. Get 2 of them off of the solid surface and the other 2 won't lock because the ones suspended in mid air are turning. Very frustrating ! Had another Mack with traction control that sensed slippage and compensated for it automatically. I liked it. When backing up your 53' trailer up to A wall remember where your tandems are. The trailer may hit the wall before the tires get to the bumper blocks. I know , I did it ! A real attention getter for the workers in the corrugated metal building and humiliating for me........

 

We were trying to get up the hill in Montana when this truck came to a complete stop in the right lane to engage his power divider. You know what happened...he got stuck on the side of an incline. Right lane is blocked. Suddenly, everyone behind him who didnt get over in time is stuck too. Theres only one thing to do when you get stuck on the side of a hill in Montana. And it's against company policy.

Notice a trend?

Why would the manufacturer make the power divider be able to lock on the fly? The goal isnt to get unstuck, its to avoid getting stuck. If you get stuck, theres only two things to do to get unstuck. 1. tire chains 2. a tow.

You hate to see them on the road. On the back roads, they come up on a farm tractor and follow him down the road. Not the hoppers, not the bullwagons, not the tankers, not the dumps. Speed limit 55-70 mph, and this truck is following the 25 mph farm tractor.

You come up on a construction zone. Speed limit drops to 55 or 45. Why is traffic moving at 15 mph? Then you see why. It's one of them.

You come up on a weigh station. Sign says MAINTAIN 45 mph. Why is everyone going 5 mph through the BYPASS LANE?!?!?! Then you see them. "Ah! Thats explains it."

You are parked in a truckstop, daytime, backrow. You are catching some Z's in preparation for your next episode of vampire trucking. Theres noone on the back row within 4 spots of you either side. CRASH! What the heck?!?! You sit up, and you see the trailer pulling foward. Then it starts backing up again. CRASH!!!!!!!!!!!! Driver's side of the truck is smashed so you have to get out on the passenger side. You get out, no shirt, no socks or shoes, holding your britches up with one hand and your other clenched into a fist. The trainer is still outside the truck giving directions to the rookie. Rookie looks bewildered because he's never seen the godlike trainer look so worried when the vampire cursed and spat upon him.