Front axle on tandem

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by biggi1996, Jun 7, 2021.

  1. AModelCat

    AModelCat Road Train Member

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    That's exactly how its supposed to work. Jack up any of the 4 wheel ends and it'll do that, not just on the rear axle.

    Think about it, with a single drive axle, both rear wheels drive. Break either axle shaft and you're stuck. The power divider is just another differential between the 2 drive axles and behaves the same way. Power splits 50/50 to both axles all the time. All locking the power divider in does is remove the differential action from the power divider. This causes both drive axles to be driven at the same speed, rather than multiply speed through the gearsets to the 1 wheel that has lost traction.
     
    lester Thanks this.
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  3. Judge

    Judge Road Train Member

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  4. dibstr

    dibstr Road Train Member

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    I was just about to chime in until you posted. I have told this to people in the past only to be told I didn’t know what I was talking about. I see below that you posted a page that explains it. Thank you, the truth really is out there.
     
    Stray_Dog, AModelCat and lester Thank this.
  5. AModelCat

    AModelCat Road Train Member

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    Its crazy how myths like that spread. If one were to pull apart a power divider, it would make more sense.

    The input shaft doesn't go straight through and out the back, it actually drives a gear which relays power down to the front drive axle pinion. At the same time the back end of that input shaft drives a spider gear on the interaxle. Effectively its just putting a mini differential between the drive axles and it behaves exactly the same. Interaxle lock simply locks the input shaft to the interaxle carrier, making it solid.
     
    dibstr and Stray_Dog Thank this.
  6. Judge

    Judge Road Train Member

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    Well would one of you explain the problem at hand instead of being myth busters and pointing out what the problem is not.
     
  7. biggi1996

    biggi1996 Light Load Member

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    Stray dog. When I put truck in gear truck will not move, rear axle spins and front won't .
     
  8. AModelCat

    AModelCat Road Train Member

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    How do you mean rear axle spins?
     
  9. biggi1996

    biggi1996 Light Load Member

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    It turns as it would if driviining, but front did not.
     
  10. SmallPackage

    SmallPackage Road Train Member

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    Does only the front diff have spring brakes on it and the rear one doesn’t? If it does. Are they releasing?
     
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