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explain foot pounds to me

Discussion in 'The Garage' started by tecton, Apr 3, 2004.

  1. tecton

    tecton 1/2 ton status

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    it makes no sense to me at all

    what is a foot pound
     
  2. velocitiii

    velocitiii Registered Member

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    ft-lb is a measure of torque or twisting motion.
    1 ft-lb is the amount of twist you would have if you had a 12 inch wrench on a bolt and you put a 1 lb weight on the very end of the wrench.
     
  3. dremu

    dremu Officious Thread Derailer Premium Member

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    the amount of torque applied by that many pounds on a lever one foot long, or one pound on a lever that many feet long, or any combination thereof.

    So for 100 ft-lbs, you could put 10# on a 10 foot lever, or 100# on a 1' lever, or 1# on a 100' lever, which in theory should all apply the same torque.

    This is why if you can't yank off a lug nut, say, you get a cheater pipe, which gets you a longer lever for you to jump and down on.

    The scientific types will jump in and give you more details, but I think that's the basic idea.

    And is it foot pounds or pound feet? I always get it wrong.

    -- A
     
  4. sandawgk5

    sandawgk5 3/4 ton status

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    I have always had it explained as the amount of energy to move 1 pound 1 foot straight up i.e. lbs-ft. That is how you can calculate horsepower based solely on a torque number.
     
  5. tecton

    tecton 1/2 ton status

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    that explains alot

    so lets say my truck makes 300lb ft or tourque...my truck puts 300lbs of force on the end of the hypothetical 12inch wrench?

    that cant be right
     
  6. dremu

    dremu Officious Thread Derailer Premium Member

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    Well, the engine might do 300 lb/ft at the flywheel -- if it's a big one, or a diesel -- but then the gear reductions of the tranny, transfercase and diffs increase that.

    So my stock 350 which puts out something like 250 lb/ft goes through the TH350 low gear which is what, ~3:1 and then the NP203 in low gear is 2:1 and my diffs are 3.73:1... so net is somehting like 5600lb/ft applied to the wheels. If I were flooring the poor girl in low/low in an ideal world of no loss, slippage, etc etc.

    This is why you can snap axle shafts /forums/images/graemlins/laugh.gif

    -- A
     
  7. Paxx

    Paxx 1/2 ton status

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    [ QUOTE ]
    This is why you can snap axle shafts /forums/images/graemlins/laugh.gif



    [/ QUOTE ]

    This just cracked me up when I read it /forums/images/graemlins/rotfl.gif

    I think it was the smiley that did it lol /forums/images/graemlins/histerical.gif
     
  8. Highjaxx

    Highjaxx 1/2 ton status

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    /forums/images/graemlins/laugh.gif

    Nice
     
  9. mike reeh

    mike reeh 1/2 ton status

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    I think everyone pretty much covered it. An interesting tidbit- if you ever look at a torque/hp curve chart, they should always be equal (torque and horsepower) at 5252 rpm.

    mike
     
  10. duece21

    duece21 1/2 ton status

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    New cat they are puttin in freightliners and kenworths

    How bout them foot pounds. For a truck engine at least, twin turbo. So now when they break people can pay $3,200 for new turbo's instead of 1,000.

    [​IMG]

    Cylinders In-Line 6
    Bore/Stroke 5.4 x 6.75 (137mm x 171mm)
    Displacement 15.2 L (928 cu in)
    Weight 2890 lb (1311 kg)
    Horsepower 435 to 550 @ 2100 rpm
    Torque 1350-1850 lb0ft @ 1200 rpm

    All for more power & Higher emissions standards /forums/images/graemlins/rolleyes.gif
     
  11. 84gmcjimmy

    84gmcjimmy 1 ton status

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    15.2 L /forums/images/graemlins/yikes.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/yikes.gif /forums/images/graemlins/eek.gif
     
  12. Highjaxx

    Highjaxx 1/2 ton status

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    I drive a truck with 500HP and about 1500ft/lbs /forums/images/graemlins/laugh.gif

    Coming out of a Detroit 60 Series turbo, with a 3 level engine brake.

    Really makes me want to buy turbo diesel pick-up.
     
  13. mogas

    mogas 1/2 ton status

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