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Left hand trhread versus right hand thread

  1. Sep 7, 2011 #1
    Does a left hand thread offer any advantages over a right hand thread?
  2. jcsd
  3. Sep 7, 2011 #2
    Left pedals on most bicycles have left-hand threads to keep the pedal from unscrewing. Some cars (MGs, e.g.) used to have left-hand lug nuts on the left side, but that's not so common anymore. Some circular saw blades are secured with left-hand nuts for a similar reason.

    Turnbuckles obviously have opposite handed threads on either end.

    Fuel gas bottles have left hand threads & oxidizer gas bottles have right hand threads as a safety measure for welders. That's why the propane tank on your gas grill is left-handed.
  4. Sep 7, 2011 #3


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    When I was a teenager I nearly stripped the lug nut studs on my Mom's '65 Dodge when changing a flat. The nut seem to be getting tighter and a friend watching suggested it might have a left hand thread, which it did.
  5. Sep 9, 2011 #4


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    They prevent unscrewing in applications where the screw fixes a rotating object, and also help to differentiate gas from hydraulic/liquid/etc lines in cars, burners, etc.
  6. Sep 14, 2011 #5
    Are u saying that gas lines are always fitted with left hand theads???
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