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3 Way Locker Question

Discussion in 'Trucks [ Eighteen Wheelers ]' started by 04 LowMax, Dec 26, 2013.

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  1. Dec 26, 2013 #1
    04 LowMax

    04 LowMax Medium Load Member

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    I have observed that with both my power divider locked in and the rear diff locked , that the wheels on the rear axle (the one with the locker) turn at half the speed
    of the wheel on the front axle. From time to time I encounter a situation where I have to chain up all axles to make a hill (grossing 140,000lbs). I usually lock it all up when I do this, but it occurs to me that might be pretty hard on something if they are trying to turn at different speeds? Maybe I should only be using the power divider in these situations? I tried to search for the answer to this but couldn't find this specific situation described.
     
    04 LowMax, Dec 26, 2013
    04 LowMax, Dec 26, 2013
    #1
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  3. Dec 26, 2013 #2
    12 ga

    12 ga THE VIEW FROM MY OFFICE

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    That doesn't seem possible to me, but go ahead and teach me something new.
     
    12 ga, Dec 26, 2013
    12 ga, Dec 26, 2013
    #2
    Inland-Pilot Thanks this.
  4. Dec 26, 2013 #3
    Heavyd

    Heavyd Road Train Member

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    With your combination you can still have one forward drive wheel slip while the other front drive wheel is locked the rear drive axle while the rear axle wheels are locked together. You do not have full locking diff on the front drive, just a locking interaxle diff. You would need full locking front and rear locking diffs with the power divider lock to lock both axles together.
     
    Heavyd, Dec 26, 2013
    Heavyd, Dec 26, 2013
    #3
    beltrans Thanks this.
  5. Dec 26, 2013 #4
    RocketScott

    RocketScott Medium Load Member

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    Does your front axle lock too?

    What you are describing is possible. The front wheels on one side spin at twice the speed because they are getting the full amount of power that the back two sets are sharing. That's how a diff works so when you go around a corner you don't ruin your tires.

    I don't know if what you are doing is ok, not a good idea, or super bad. Just think about how the power gets to the ground though; if you have everything locked and only one set of tires is gripping, your whole 140k is being pulled by one half shaft.
     
    RocketScott, Dec 26, 2013
    RocketScott, Dec 26, 2013
    #4
    Cetane+ and 04 LowMax Thank this.
  7. Dec 26, 2013 #5
    Rock hauler

    Rock hauler Light Load Member

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    Deridder La.
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    sounds like different ratio in front and back or different sizes tires. one of our trucks has full locker and they spin the same no matter what, or break. may be something out there I haven't seen, but that's how ours work. went back and read your post don't know about 3 way lockers could happen if one front wheel was not spinning.
     
    Last edited: Dec 26, 2013
    Rock hauler, Dec 26, 2013
    Rock hauler, Dec 26, 2013
    #5
  8. Dec 27, 2013 #6
    beltrans

    beltrans Medium Load Member

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    Nov 26, 2008
    spokane wa
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    Read post #3..........
     
    beltrans, Dec 27, 2013
    beltrans, Dec 27, 2013
    #6
  9. Dec 27, 2013 #7
    ENR

    ENR Light Load Member

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    yup, it's fine. Your back axle isn't going at half speed it's just that your single front wheel position is going double time because your front diff is open.
     
    ENR, Dec 27, 2013
    ENR, Dec 27, 2013
    #7
    kylefitzy, Cetane+ and 04 LowMax Thank this.
  10. Dec 27, 2013 #8
    04 LowMax

    04 LowMax Medium Load Member

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    Yes, I get that, however nobody has yet answered my question. If I am pulling a hill chained up and locked up what's going to be happening between the tires and the ground? Either my locked up rear axle isn't going to be doing me much good, or will the faster turning front one will be taking all the strain? And, just to make this more interesting is a further question. If locking the rear diff across reduces the wheel speed by half, why didn't that use to happen when I had full (4-way) lockers on a previous truck? I would often lock it up on the fly to climb a hill, with no ill effects. Wheel speed was the same locked up or not on that one. This truck, a locked-across diff cuts the speed in half. Note (the condition I have described, was observed in my yard, "spinning out" at idle on purpose to see what was taking place.) I have a hunch that when you are in motion, things may be different, otherwise things would be breaking and snapping. But there must be somebody who can properly explain what is going on? If not, I'll just let it go, and thanks to everyone for their ideas.
    I
     
    04 LowMax, Dec 27, 2013
    04 LowMax, Dec 27, 2013
    #8
  11. Dec 27, 2013 #9
    25(2)+2

    25(2)+2 Trucker Forum STAFF Staff Member

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    the road less travelled
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    If you chain it up, all drive duals, it will probably quit spinning at double speed . I've never driven a Class 8 with differential locks, but when you chain up, and it works, wheel spin is reduced to little or negligible with only a power divider lock.
     
    25(2)+2, Dec 27, 2013
    25(2)+2, Dec 27, 2013
    #9
  12. Dec 27, 2013 #10
    DL550CAT

    DL550CAT Road Train Member

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    Waynesburg, Pa
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    Your locked axle is not running half speed. If all wheels are getting equal traction they are turning the same speed. Your rear axle is going to run the same speed side to side no matter what as it's locked. There can be a difference in speed between your front axle side to side as it's not locked. That difference only comes into play when one side loses all traction it can spin faster but that speed difference is coming from the front differential.
    An easy way to prove it is lock everything in on dry pavement and try to move. If what you say is true you will be gear bound and the truck would not move without breaking something.
     
    DL550CAT, Dec 27, 2013
    DL550CAT, Dec 27, 2013
    #10
    beltrans, tw1005tx, Cetane+ and 1 other person Thank this.
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