How many lockers to use for a 6WD M1088?

[coachgeo]

from what Scottmandu reported seems middle is best, but only marginally.

Seems to me... and am no engineer.... Based on that there is a differential that sends torque to both axles... but mostly to the one that has some slip... any axle in the 6x6 pair with Detroit in it will get sent potentially less torque overall in general cause the Detroit axle will be the one NOT to slip as often . When in mode the torque is split equal to both axles and locker now is in maximum affect. Not sure in mode if one axle is better than the other when deciding where best to have it installed.

So with that in mind and being that no matter what axle it is in... a Detroit is always active along with it's differential. It will begin to lock the slipping side at some point in a turn (thus some scrubbing of tire on cement). The furthest back axle will have a higher radius in the turn compared to middle axle in front of it. Thus it will scrub more due to this. For tire wear this says middle axle is better. (if understanding all this correct.) If you don't care about tire wear... sounds like it makes no difference?

Anyone else see it that way? If any of you have a clearer or different understanding please to speak up. Figure its bound to be helpful to others who want to get their head wrapped around the understanding of how the rear pair of axles in a 6x6 work.

 

[coachgeo]

So for a vehicle that is driven a lot on the highway, a locker in the rear is likely the best because the rear only locks when it is activated by operating in MODE? And there would be reduced tire wear?

We need more snow videos of 5 ton trucks to look at what it does when it slips : )

Well that is where the conflict is. Seems some have come to the thought you describe above of rear most is a floating Tag axle till put in mode and activating it. Yet others have pointed out that it looks like there is a normal differential in the Power Divider thus that school of thought would be incorrect.

Heck maybe it is a little bit of a combination of both??? as in the differential could be designed to prioritize the middle axle to get say 70% torque and 30 rear, unless slip dictates a change.... or until mode is called upon. Then you get a locked split at 50/50??? But that school of thought has not been mentioned at all. Just throwing it out there as something to mull over.

 

[Jbulach]

How many lockersto use for a 6WD M1088?

Don’t someone own and use one of these trucks?
Instead of endless debate on how it might be designed, take it out, chain it to a tree, depress the “go” pedal, and report back...

 

[Reworked LMTV]

Don’t someone own and use one of these trucks?
Instead of endless debate on how it might be designed, take it out, chain it to a tree, depress the “go” pedal, and report back...

Ummm...based on the videos i see on the M1088, the tree loses LOL

 

[Jbulach]

How many lockersto use for a 6WD M1088?

Ok, tie your tuck to your wimpy tree, jack up one wheel at a time, if it is a typical power divider, each wheel will easily spin while in the air, with no real force applied to your wuss tree

 

[Reworked LMTV]

Interesting article

https://www.tradetrucks.com.au/product-news/1510/gaining-traction-power-dividers-versus-diff-locks

 

[Reworked LMTV]

Based on the suggested reading, it appears that all 4 wheels are driven "In a 6x4 truck, both axles are driven at all times. The only thing the power divider/interaxle differential lock does is lock the outputs to each axle so that they always rotate at the same speed. If a wheel slips on one axle, this prevents all the torque from flowing out with it"

 

[FMTV Truck Sales]

Gents-

Please don't kill any little trees! Haha

I can tell you definitively that the 6x6 rear axle has no power to it unless the transmission is shifted into MODE. The "best" placement for a locker is purely based on owner preference. We put the Acela Monterra lockers in the rear axle so that they are effectively selectable (and do not scrub when not in MODE), but there's certainly nothing wrong with choosing to place the locker in the intermediate axle or both (monster-like)...my 2 cents.

 

[DiverDarrell]

With my locker I have found that I really have to be on the throttle while turning to get it to lock up and scrub. These are not the Detroit’s of the past that’s for sure. I guess I’ll have to buy an MTV for my self to further research this discussion and tell my wife it’s all for science. Lol

 

[Jbulach]

Gents-

Please don't kill any little trees! Haha

I can tell you definitively that the 6x6 rear axle has no power to it unless the transmission is shifted into MODE. The "best" placement for a locker is purely based on owner preference. We put the Acela Monterra lockers in the rear axle so that they are effectively selectable (and do not scrub when not in MODE), but there's certainly nothing wrong with choosing to place the locker in the intermediate axle or both (monster-like)...my 2 cents.

If this is correct, my vote would be for the rear axle as well, but if you can afford it buy more!
As for the trees, kind of like natural selection, if they can’t take it, it wasn’t meant to be...

 

[Duckworthe]

I love the post by those who don't even own the truck adding there opinions on "how it should work" Cracks me up!!!!

 

[coachgeo]

I love the post by those who don't even own the truck adding there opinions on "how it should work" Cracks me up!!!!

Devils advocate, just throwing this out there..... that is like saying a "Heavy truck mechanic, an Automotive engineer or say a Dakar truck builder.. should offer no thoughts"..... "if they don't own an FMTV"?


when get a chance will try to put a socket drive to my 6x6 axle and see what the output does. Got to find huge jackstands and a way to lift the axle out of the bed of my truck first though.

 

[Jbulach]

I love the post by those who don't even own the truck adding there opinions on "how it should work" Cracks me up!!!!

Yep, same thing with the age old debate on which axle of a 6x6 to run tire chains on, always more opinions from 4x4 guys.

All my tree joking aside, I shouldn’t bust on these guy’s too hard about how power dividers work, I’d bet 75% of professional truck driver don’t understand them.

 

[Jbulach]

Devils advocate, just throwing this out there..... that is like saying a "Heavy truck mechanic, an Automotive engineer or say a Dakar truck builder.. should offer no thoughts"..... "if they don't own an FMTV"?


when get a chance will try to put a socket drive to my 6x6 axle and see what the output does. Got to find huge jackstands and a way to lift the axle out of the bed of my truck first though.

Coachgeo, you don’t have to do all that, if you have an intermediate axle laying around. If it has a typical power divider, turn the input and the output will turn backwards while unlocked. If FMTV Truck Sales is correct, the input will not turn with locked brakes, but the output will spin free

 

[coachgeo]

Coachgeo, you don’t have to do all that, if ywu have an intermediate axle laying around. If it has a typical power divider, turn the input and the output will turn backwards while unlocked. If FMTV Truck Sales is correct, the input will not turn with locked brakes, but the output will spin free

Will see what I can do . It is nailed up in a crate.

 

[scottmandu]

If there is no power to the rear axle without mode being activated then what is the purpose of the interaxle differential in The center chunk and why does the rear axle rotate if the center axle is held stationary?

 

[Reworked LMTV]

Should I assume that any axle that has a non-actuated locker is locked up all the time? If this is the case, would not scrubbing occur with that axle is engaged or not? Maybe I am wrong.

I did some research on Meritor's site. It would seem that they divide their power 50/50 to the rear axles. I also saw where they are going to more 6x2 for fuel economy.

 

[Coffey1]

Well I do own a 1088!
And when it's not in mode it will get stuck easy.
Put in mode and drop air from tire's and it's a tank.

 

[Johno176]

Scottmandu, you are correct about the functioning of the interaxle differential. The two axles with the interaxle differential connecting them, function together as on open differential system(axle with slippage gets the power). First look at the simple example of the middle axle having both wheels bound together with the same force so there is no movement. As an open differential system power is then sent to the rear axle. Conversely if the rear axle wheels have more frictional resistance then the middle axle, power is transferred to the middle axle. Now when the interaxle differential is locked, the axles now function together as two separate open differentials. When the interaxle differential is not locked and there is any slippage of the middle axle, no power is sent to the rear axle until the lock is actuated.

 

[coachgeo]

Scottmandu, you are correct about the functioning of the interaxle differential...... When the interaxle differential is not locked and there is any slippage of the middle axle, no power is sent to the rear axle until the lock is actuated.

so sounds like everyone is basically "sorta" correct, "in general" cause in most normal situations; when NOT in mode, sounds like the power tends to stay in the middle axle cause it is (sorta) powered first.... and thus slips first... keeping the % power there the most. Which in effect leaves rear axle less often activated.