Does overly biased tandem weight add drag?

Discussion in 'Experienced Truckers' Advice' started by Pmracing, Nov 10, 2017.

  1. Numb

    Numb Crusty Curmudgeon

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    tandems are not exclusively trailer wheels.
    drives are also tandems.
     
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  3. Pmracing

    Pmracing Road Train Member

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    Duel drive axles, Tandem trailer group are the accepted nomenclature.

    Mikeeee
     
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  4. MACK E-6

    MACK E-6 Moderator Staff Member

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    I had that issue with my last 2 loads, with the trailer tandem around 27k and 14k on the single drive.

    That gets a little bouncy.
     
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  5. spyder7723

    spyder7723 Road Train Member

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    That last set i brought out of Chicago i had nothing on the drives and swear the front trailer might have had 500 lbs in it while the rear was fully loaded. Now that one fought me every mile the whole trip.
     
  6. Oldironfan

    Oldironfan Road Train Member

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    I'm with most weight on drives when possible. You back will thank you. Always seems like momentum up hill will hold longer also. And down hill will gain momentum faster. Try it for yourself. And keep tires inflated above 100psi if virgin.
     
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  7. MACK E-6

    MACK E-6 Moderator Staff Member

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    And you pulled it like that? Yikes....:eek:

    Never run a set down the road with the heavy in the back. It rides like crap and it’ll be easy turn over.
     
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  8. spyder7723

    spyder7723 Road Train Member

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    I was down the road a good ways before i figured out what was going on. Remember who i was pulling for. No bill of lading to look at for weights. I could have found a place to stop in Gary and waited till they sent someone to break them down and set them back up(our contract forbids us from doing that), but that would have taken longer than just slowing down and taking it easy to drop hub.
     
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  9. LilBudyWizer

    LilBudyWizer Light Load Member

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    Their explaination is wrong. It's really how much force is lost to trying to rotate the trailer about the tandems. That would be front of the trailer up or down. The actual transmission of force is complicated but presumably it's engineered on the assumption you're balanced at the 40' mark. Force going to rotation, i.e. torque, is lost. High vs low center of gravity has an effect as well. Your tire inflation would have a great deal more impact on your fuel economy though as would speed. That bouncy ride lets you feel a good deal of the force you're losing.
     
  10. x1Heavy

    x1Heavy Road Train Member

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    *Puts on old man trucker hat...

    You are referring to what is known as the center of gravity.

    ALL vehicles on the planet, on the earth, under the sea, and in the sky above as well as space has a center of gravity. Trucks generally have it around 14 inches above a deck on the flatbed somewhere 2 feet or so ahead of the center marker light roughly. If the Lord amuses himself to pick up a truck and trailer that's loaded to put onto his finger to spin it around that would be where he puts it.

    Anything on the rear trailer in excess weight such as Ravens Covered Wagon two spread axles at 40K and the drives whatever they are provided the entire vehicles at 40 ton exactly gross overall then all is well.

    But put 40K on a set of ordinary trailer tandems back there and suddenly you have a truck that is going to be dragging on you, beating you up on bridges and in general being a onery government mule with a bad temper liable to turn over on you too. Makes sense?
     
  11. Oldironfan

    Oldironfan Road Train Member

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    For all the drivers that do not think there is no difference either way.
     
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