Coupler Strength

Discussion in 'The Real Thing- North America' started by jasonboche, Jan 29, 2003.

  1. jasonboche

    jasonboche Member

    One thing that has always amazed me is couple strength.

    Consider a long string of cars being pulled by a locomotive. The pulling coupler on the locomotive and the couplers on the first couple of cars must have tremendous strength because they are pulling the weight of the entire string of cars. I am very surprised that the couplers put up with the stress and do not break or suffer catastrophic failure (yes, I know that some do once in a while).

    Anyone know how coupler strength is rated? What is the theoretical limit to the amount of cars a coupler can actually pull without failing? In one of my rail fan VHS videos, locomotives are pulling a 9,000 foot string of cars. That's almost 2 miles of cars.

  2. BDC

    BDC Member

  3. CarlFidy

    CarlFidy Member

    Thanks for the link...

    Info on that first link is very interesting, considering I saw a BNSF train go into emergency last weak and break 2 knuckles about 10-15 cars back....
  4. MCL_RDG

    MCL_RDG Member

    Broken couplers!

    I was amazed while railfaning to find myself stepping over the carcass of a coupler broken into two pieces. I had never conceived that a huge chunk of iron like that could be pulled apart. I had heard the phrase "broken coupler" uttered on the scanner or TV (as a reason for a derailment) but never appreciated the meaning 'till my personal encounter.

    The break was just behind the knuckle. The shank layed against it.

    I designed hydraulic cylinders (up to 22" Dia) and worked with Column Strength Charts to calculate wall thickness to diameter capacities- over lengths to 100'. I am fascinated with the engineering aspect brought forth.

    A very interesting subject.



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