3 Way Locker Question

Wow, I would have never thought someone would set rears up that way. Im not trying to put you down but, are you sure there is not a locker in the front, and how do you know? Can you snap a pic of the front rear, passenger side gear housing around where it bolts to the banjo? Maybe a previous owner had the front gear set changed and didnt want to pay for the locking diff?

 

No pusher axles as they are not allowed in Alberta. A regularly registered (no permit required) Super-B is allowed up to 63,500 kg (139,992 lbs) distributed as 5,500 kg (12,125 lbs) steers, 17,000 kg (37,478 lbs) tandem drives, 24,000 kg (52,910 lbs) tridem (lead), 17,000 kg (37,478 lbs) tandem (pup).

 

Lots of older Peterbilts setup that way with Eaton rears. I owned 2 of them. No diff lock in front driver.

 

Thanks. I'm learning. I've been watching a lot of "trucking with Sergie" on youtube. He always explains how things are different in Canada vs. the USA. Great learning experience, and a lot of differences I would have never guessed.

 

Lots of times having both diffs locked does push the truck straight. Usually it only happens at slow speeds and/or where there is very low traction for the steers or they unload slightly. I will sometimes unlock the rear diff to negotiate a turn, but always re-lock it when straight. I always use both and the PDL when I use them.

 

My point is he had it backwards, and blew the small drive shaft with all the torque to the rear rear.

 

Yes, I am sure. I can identify both a pdl unit and a cross lock unit. Many trucks around here are set up with 3way only. But you also find lots with only pdl and, even brand new ones (which blows me away-I would never buy a new one with anything other than full lockers anymore, bought this one used so that's how it came) It will be interesting to see what comes to light in the new thread titled "Full Lockers?" I am thinking with only one switch thistruck has only the pdl. Either that or he hasn't found the other switches yet.

 

Doesn't it seem to reason that the primary route of torque is ALWAYS across the rear drive shaft? I mean, the first tire to slip in evenly low traction is the right rear drive and you can turn the engine by raising only that wheel and releasing the brake (such as when doing valve or clutch adjustments).

It also makes this apparent because when the power divider starts to eat itself, its always been my experience that the geartrain leading to the rear output has been lunched while other related parts show little or no wear beyond normal.

Granted, locking the rear diff will increase the stress due to the loss of wheel spin, much the same way a heavy car would break axle shafts with a spool while a pickup lives because it will spin one tire.

I would place grater blame on driver technique or the extreme conditions involved at the time of failure. We all know that quick changes in wheel speed from gaining and loosing traction repeatedly is the absolute best way to break driveline parts and a defective wingnut on the throttle will exacerbate that greatly.

Just my thoughts. I'm sure I could be wrong. Sorry to hijack...

 

If the transmission is in gear and you release the brakes, even with no lockers engaged, you best be able to turn the engine with any one tire lifted. If not, something is busted.
If you know how the power divider works, you know that the front driver pinion rotates opposite direction of the rear pinion. The rear pinion rotates the same direction as the engine crankshaft. The pinion will attempt to climb the ring gear and the rotational torque of the engine will want to lift the right wheel.

Here's a pdf you might be interested in.

IMO.