Air Power Divider:

[Rob]

This afternoon I wanted to test the power divider in my R model that has an air lock power divider. I nosed the truck up to a large tree, placed the transmission in lo lo, eased the throttle while releasing the clutch and the tires on both sides of the rear rear started to dig into the gravel driveway. I then engaged the power divider and repeated the sequence and again both sides on the rear rear went to digging, and the left side of the front rear also started digging. After flipping the dash switch to unlock, I again applied power and let the clutch out and the same thing happened with both rear axles.

My questions are these:

Does a power divider not release until the truck is driven for awhile after releasing the air pressure?

Is it normal in a Mack differential, (drop in type) to power the left side wheels as opposed to the right on conventional, (single reduction) axles?

Thanks,

Rob

[Packer]

The power divider locks up the diff's so that one wheel on each axle will turn.

With-out locking, NORMALLY, one wheel of four will turn.

The power divider is a differental in and of it's self.

Locking in the power divider takes that differental out of play.

It's like four wheel drive. One axle or two but instead of a manual shift, you use air.

[HK Trucking]

This afternoon I wanted to test the power divider in my R model that has an air lock power divider. I nosed the truck up to a large tree, placed the transmission in lo lo, eased the throttle while releasing the clutch and the tires on both sides of the rear rear started to dig into the gravel driveway. I then engaged the power divider and repeated the sequence and again both sides on the rear rear went to digging, and the left side of the front rear also started digging. After flipping the dash switch to unlock, I again applied power and let the clutch out and the same thing happened with both rear axles.

My questions are these:

Does a power divider not release until the truck is driven for awhile after releasing the air pressure?

Is it normal in a Mack differential, (drop in type) to power the left side wheels as opposed to the right on conventional, (single reduction) axles?

Thanks,

Rob

Hi Rob.

After you flip the air switch to disengage the P.D. lock, sometimes it won't actually disengage until the

strain, or torque buildup is relieved between the front and rear differentials.

I've noticed that when I've flipped the switch to disengage, there is a puff of air as the pressure is released from the P.D. lock cylinder, then a few seconds later, once the truck is underway again and the torque strain between the axles was relieved, I would sometimes hear another smaller puff of air as the P.D. lock actually disengaged itself and the cylinder retracted.

I have never noticed any right to left bias with this system, just the usual "wheel with less traction will spin first" syndrome.

[other dog]

But what about the tree ? Is it still upright ?

[Rob]

Hi Rob.

After you flip the air switch to disengage the P.D. lock, sometimes it won't actually disengage until the

strain, or torque buildup is relieved between the front and rear differentials.

I've noticed that when I've flipped the switch to disengage, there is a puff of air as the pressure is released from the P.D. lock cylinder, then a few seconds later, once the truck is underway again and the torque strain between the axles was relieved, I would sometimes hear another smaller puff of air as the P.D. lock actually disengaged itself and the cylinder retracted.

I have never noticed any right to left bias with this system, just the usual "wheel with less traction will spin first" syndrome.

Hi Herb,

I was thinking along the same lines as you stated as far as the power divider releasing due to torque bind but wasn't sure if there was a disengagement spring or not. The one thing that was consistent with this tractor is that the rear rear differential did not slip one side or the other loose. Both sides stayed driving the tires like a posi traction differential. This tractor being an "oil field" spec unit, could have had some type of traction enhancement differential installed, but I have no proof, as the truck does not appear to have been built with one, (according to the line set ticket).

Thanks again,

Rob

[charlie]

After you flip the switch to unlock back up a liitle and it will unlock. You can hear it lock, but not unlock.

[57 bcr]

I had the "PDLO" on my 1990 RD690S. Loved it when you had a swail or ditch or cut out to go through.It didn't care if you had a wheel off the ground as in my '79 with the automatic power div..Was glad not to have to tap the brake pedal to get the auto. to engage,as the old timers taught me!