How many lockers to use for a 6WD M1088?

[Reworked LMTV]

I think the some of the confusion stems in part from the use of the terms "locked" and "locker". Maybe someone could draw a simple stick diagram to help ?

 

[coachgeo]

I think the some of the confusion stems in part from the use of the terms "locked" and "locker". Maybe someone could draw a simple stick diagram to help ?

you might be right... though feel it may be more than that. The lock of the power divider.... that locks the two axles together..... IS essentially a locker.... works basically like an ARB... but it locks a differential that sits between two axles instead of a differential between two wheels. Any differential could have a locker and it will lock together whatever is on each end.

So once one understands a Power Divider is essentially a differential it gets easier to understand. And when realizing that it acts in the same manner as a differential inside ONE axle, it makes more since. Think of Power Divider like a Pumpkin sitting between axles. Really gets clear when one sees that any automotive "differential" distributes what gets torque based on how much one "thing" revolves compared to another "thing". Does not matter if those "things" are two different axles; such as the one in the Power Divider.... or the Left / Right wheel, inside a single axle. AKA It "differentiates" what is happening to one thing compared to another, and applies torque to the one revolving the most. (example: outside wheel in a turn, or wheel slipping in mud)

With that understanding then one can see what a locker would lock together, based on where it is located..... If it is inside a Power Divider.... it will Lock two axles together.... If it is inside a single axle..... it will lock Left and Right wheel together. No more "differentiating" occurs cause... both "things" get torque; no matter what, cause they got "locked" together.

or did I just make it more confusing lol

PS to add to the confusion.... there is a different type of power divider.... but our trucks to not have that type (6x2)

 

[Coffey1]

 

[Reworked LMTV]

you might be right... though feel it may be more than that. The lock of the power divider.... that locks the two axles together..... IS essentially a locker.... works basically like an ARB... but it locks a differential that sits between two axles instead of a differential between two wheels. Any differential could have a locker and it will lock together whatever is on each end.

So once one understands a Power Divider is essentially a differential. It is one that acts in the same manner as a differential inside ONE axle but instead sits between two axles. Think of Power Divider like a Pumpkin sitting between axles. Makes more since when one realizes any automotive "differential" distributes what gets torque based on how much one "thing" revolves compared to another "thing". Does not matter if those "things" are two different axles; such as the one in the Power Divider.... or the Left / Right wheel, inside a single axle. AKA It "differentiates" what is happening to one thing compared to another, and applies torque accordingly.

With that understanding then one can see what a locker would lock together, based on where it is located..... If it is inside a Power Divider.... it will Lock two axles together.... If it is inside a single axle..... it will lock Left and Right wheel together.

or did I just make it more confusing lol

Ah, ok so I think I do understand your explanation. So is the tire that has the least traction detected and the power flows to the grippiest tire assuming it is in MODE, or is this not the case, and power flows to the tire with no traction, and thus the reason people want the Detroit style locker, to lock both tires on one axle?

 

[coachgeo]

Ah, ok so I think I do understand your explanation. So is the tire that has the least traction detected and the power flows to the grippiest tire assuming it is in MODE, or is this not the case, and power flows to the tire with no traction, and thus the reason people want the Detroit style locker, to lock both tires on one axle?

... OK if I understand all this right.....

When it comes to lockers... Mode ONLY "directly" affects the locker inside the Power Divider on MTV 6x6 trucks. In Mode it kicks on an ARB type locker in the Power Dividers differential locking the two rear axles together so they both are powered equally no matter how much one axle is revolving compared to the other.

In stock mode there is no lockers installed in any of the differentials between Left and Right wheels. There is where people are adding a Detroit (but hoping to find an ARB type eventually)

For a locker that is added to a Differential between two wheels..... In that configuration whether in Mode or NOT... the differential sends torque to the wheel "revolving" the most. This is done so in a turn the outside wheel can turn more and the inside wheel... turn less. BUT that also means the wheel in the mud revolving most..... will also get the torque... and you sit there spinning one wheel going no where. Granted on these trucks it would really mean your not moving cause one wheel in front is spinning in mud and one wheel of axle(s) in back spinning too .... thus your not moving... since FMTV's are AWD. Same would happen in any 4x4 or in these trucks in Mode if a wheel in all axles are spinning. Idea here is to have a locker between wheels locking together two wheels no matter what axle it is in .... by either a push of a button (ARB and similar) or like a Detroit does, after a *certain number of times the one wheel revolves more than the other- then it locks automatically.

Once anything is locked be it left and right..... or two rear axles... that tends to get one out of the mud due to extra help from more wheels. BUTT not always... hence why folk want an extra locker between wheels and not just the one in the Power Divider.... BBBBut between wheel lockers also makes it hard to turn..... (hence why automatic lockers between wheels in front axle not recommended... selectable best in front) or can cause rig to slide sideways when traversing a slippery side slope. (also why some prefer selectable locker like ARB.. to get around this issue)


*not exactly how it works..... a very loose and not accurate description, but IMHO is an ok way to get the idea of it locking on its own automatically. Below is how it actually works but not too germane till you read/understand the concepts above.
Here is how it works for real


Ps- thank you to all of you who have put up with my past errors... pointed them out respectfully and helped me and others learn along the way. Hopefully my description above interpreted from what ya'll have pointed out in the past, has at least some accuracy. Please point out where I FUBARED... we all learn more from our errors than we do from what we do right.

 

[scottmandu]

The power divider completely disconnects the rear most axle ...

I can tell you definitively that the 6x6 rear axle has no power to it unless the transmission is shifted into MODE.

These statements are incorrect BTW. Spin the input on the power divider (as I just did) with it unlocked and hold the rear output and the middle spins. Do the same with the middle locked and the rear output spins. With the divider unlocked torque is varied between the two axles. By locking the power divider the differential in the unit is defeated. This is also how the manufacturer states operation is.

 

[Jbulach]

These statements are incorrect BTW. Spin the input on the power divider (as I just did) with it unlocked and hold the rear output and the middle spins. Do the same with the middle locked and the rear output spins. With the divider unlocked torque is varied between the two axles. By locking the power divider the differential in the unit is defeated. This is also how the manufacturer states operation is.

Well there we go, it’s a plain old typical power divider after all...

 

[162tcat]

These statements are incorrect BTW. Spin the input on the power divider (as I just did) with it unlocked and hold the rear output and the middle spins. Do the same with the middle locked and the rear output spins. With the divider unlocked torque is varied between the two axles. By locking the power divider the differential in the unit is defeated. This is also how the manufacturer states operation is.

Sometimes you have to push away from the computer and physically check. Thanks for clearing everything up!

Sent from my LG-M210 using Tapatalk

 

[Camel Driver]

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.

I've been thinking about this for a while for my own M1083 in the future. My thinking is, probably the only reason we are interested in lockers are for the off road traction. On road we will have some increased tire wear no matter the positions so........the center axle would probably be the best to install it on. Especially if you are planning on traveling on very uneven ground. If you have ever seen any videos of three axle trucks off road, it is amazing how often the back axle is hanging in the air doing nothing at all on ROUGH terrain. I believe the locker would spend more time being useful if it were on the middle axle.

The question I would like answered is, if you install lockers on BOTH rear axles, how does the truck handle on pavement. Has anyone driven one with both rears locked? I've driven a semi-truck with the middle locked. It wasn't bad because of the trailer weight but, it was much more noticeable when running bobtail. It would actually "push" straight a little bit on wet pavement. I have also owned a Jeep CJ with a true locker (No Spin) on the rear. That thing was an amazing handful to drive anytime it was in 2WD. Just wondering how bad two lockers would be on pavement when lightly loaded. I'd hate to have the lockers totally ruin the driving experience of my M1083 by wanting to go straight around every curve in the road when it's wet. They can also do some strange dancing around when they lock/unlock when you adjust your throttle position going around a curve or corner. The bobtail semi would actually try and fishtail on wet cloverleaf entrance ramps when getting on the interstate. NOT a fun thing when it catches you off guard. Even if you are expecting it, it can lead to an increased...........pucker factor.

 

[Camel Driver]

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.

Except when the locker gives you a (rare) bit of differential action such as when there is a good amount of weight on the axle and you are "freewheeling", it is always locked. It will lock "tighter" if you put any sort of torque on that axle. Such as when you are applying throttle or engine braking. And when it does give you some differential action, it makes a pretty good BANG. But before it skips a tooth and bangs, the locker makes the whole driveline wind up. The lighter the vehicle/load, the more noticeable it seems to be. And that can make for some scary handling. One locker can be bad enough at times. That's why I'd like to know how much more TWO lockers would affect these trucks on pavement. I'd like as much traction as possible off road but not at the expense of being constantly paranoid, waiting for my truck to scare the poop outa me.

 

[coachgeo]

could swear I read that longer wheel base vehicles do not suffer as much rear steer effects with auto lockers like Detroit's. Guess that makes a little since cause the travel of inside rear wheel in a turn, rotates a lot compared to a short wheel base where the inside tire rotates much less. With that in mind...... maybe the rear most axle is best place for locker to lessen on road effects.

Does not really help answer the question about effects of locking both rear wheels though.

 

[Suprman]

You really don’t feel the locker in the 4x4 when driving on the road. Maybe because the truck is awd. Or it’s just so heavy.