Tandem Axle Differential Power Divider Lock

Image courtesy Eaton Fuller Company/roadranger.com

Maybe it's just me, but there seems to be a lot of confusion out there about what a power divider lock is, how it works, and how it should be used.

I must admit...after perusing the internet for days trying to find a definitive answer, I'm more confused now than I was before.

Many moons ago, I was taught that one doesn't cruise down the interstate at speed for hours with the PDL engaged, and that PDL engagement should only be used for short periods, at slow speeds, in slick conditions, or to get yourself unstuck from mud, snow, muck, and goo.

This seems to be mostly accurate, but I wanted to know for sure.

Like all truck drivers, everybody has their own opinion.

Many of these opinions, it seems, are incorrect.

Knowledgeable mechanics are a good source of information, but sometimes I've found their explanations are too technical for the average dummy like me. 

So...like my dad always said, "When all else fails, read the instructions!" 

That is exactly what I did.

The following two scans are from pages 127 and 128 of the International/Navistar operator's manual which I found in my 2012 International Maxxforce tandem axle tractor equipped with a PDL switch.

Hopefully, this clears a few things up.

Please note:  Tandem axle power divider lock (PDL) is not the same as driver-controlled differential lock, and I'm too stupid to explain the difference between the two.

Different tractors may be equipped with different axle/differential controls.  It is important to know how your tractor is equipped, how it works, and how the controls function.

Otherwise, you may cause expensive noises and scatter your drive-train all over the interstate.

Doing so would be below average in just about anybody's book!

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How A Differential Works