axle interlock

Discussion in 'Trucks [ Eighteen Wheelers ]' started by chrisut, Mar 19, 2013.

  1. chrisut

    chrisut Bobtail Member

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    I'm sorry if this sounds like a dumb question, but how does the axle interlock work?
     
  2. allan5oh

    allan5oh Road Train Member

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    Your front pumpkin essentially has two differentials in it. The first one divides the power between the front and rear differentials. The second one is your front differential and acts like the differential in your rear pumpkin, it splits the power side to side.

    When you lock the power divider, you're forcing both front and rear differentials to turn the same speed. Essentially instead of just one wheel spinning, now you need two to spin in order to get stuck.

    A common misconception is that the front differential receives no power unless the power divider is "engaged". This is completely false. All four wheel ends receive power regardless if the interaxle is locked or not.
     
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  3. Hammer166

    Hammer166 Crusty Information Officer

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    :biggrin_25514::biggrin_25514::biggrin_25514::biggrin_25514::biggrin_25514::biggrin_25514: Clear, concise, and absolutely correct!

    Now, prepare for the idiocy to follow...
     
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  4. SmokinCAT

    SmokinCAT Road Train Member

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    Depending on the rear end should be added to your statement. The old rockwell rears that have the thru shaft do not drive the front axle at all unless the power divider is engaged. The only way there is power to the front rear is if the actuator moves a slip yoke on this shaft and engages the splines and allows the main shaft to turn the power divider.
     
  5. allan5oh

    allan5oh Road Train Member

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    There's exceptions to every rule, and that would be it.

    There's also "common knowledge" out there that you should run with the interaxle locked all the time. This is a huge mistake, it wears tires out faster, and puts substantial strain on the power divider. Slippery/wet conditions only.
     
  6. chrisut

    chrisut Bobtail Member

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    is it something that can be added at some point or do you have to have a rear end specifically designed for an interlock? I have two trucks with an interlock switch, and two without.
     
  7. Hammer166

    Hammer166 Crusty Information Officer

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    look at the divider in the trucks, it's possible the lock is there and just not plumbed to a switch.

    From Tapatalk- for when you're really addicted.
     
  8. chrisut

    chrisut Bobtail Member

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    what should I look for? the ones that don't have the switch are a mack with the camelback suspension and a pete with airride suspension
     
  9. Hammer166

    Hammer166 Crusty Information Officer

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    look at the trucks that have them. You will see the actuator with the airline going to it on the front half of the front rear. You'll know what to look for on the others. Some Mack rears have a limited slip design to the power divider, no external control. Take the vin to dealer, they can tell what you got. Same for the Pete. If you can find a knowledgeable parts guy, anyways.

    I'm away from truck or I'd snap you a pic.

    From Tapatalk- for when you're really addicted.
     
  10. blanco

    blanco Road Train Member

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    Engage before entering slippery conditions. It does you no good once your stuck.

    Our freighshaker even has full locking diffs in rear axle.

    Good to have when deliverying to jobsites with flatbed