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View Diary: More Mystery Surrounds Canadian Ghost Train: Where are the locomotives? (160 comments)

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  •  The train did roll backwards (2+ / 0-)
    Recommended by:
    BlackSheep1, Lujane

    The photo is taken from the town looking west.  The inertia of the locomotives would have helped push the cars off the track in front of them.  The weight of the cars pulled the engines back- brakes on or not.

    •  My understanding is that (11+ / 0-)

      Loco brakes require the power plant running. They also have handbrakes, essentially for parking.

      Train brakes are different. If there's low pressure in the train line, the cars' brakes engage. If there's high pressure, their individual air reservoirs pump back up.

      That's why the old term for slamming on the brakes of a train is " to dump the air. "

      Thump! Bang. Whack-boing. It's dub!

      by dadadata on Thu Jul 11, 2013 at 10:47:08 AM PDT

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      •  I must be wrong- engines ahead of the derailment (5+ / 0-)
        Recommended by:
        Stwriley, Joieau, Lujane, dadadata, pgm 01

        Looking at the pictures, the tankers piled up and were blocking the tracks.  The locomotives must have made it through the switch with a handful of cars behind them.  So the photo is looking east towards the town.  This would mean the tankers pushed the locos downhill.

        •  So it would appear. (2+ / 0-)
          Recommended by:
          pgm 01, NYFM

          This is interesting because the traction motors on each loco axle would exert braking force. Rolling them downhill causes them to become generators.

          When this is done on purpose it is called dynamic braking, but it generates so much current that big resistor grids are used to burn off the energy as heat.

          Dunno but suspect the motors, if pushed downhill like that, would burn up without the resistors switched in.

          On these locos the Diesel engine runs a huge generator which powers large DC motors on each axle. There's no mechanical transmission.

          Thump! Bang. Whack-boing. It's dub!

          by dadadata on Thu Jul 11, 2013 at 04:30:15 PM PDT

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    •  that's my understanding of how gravity works (0+ / 0-)

      things want to roll downhill. Engines being heavier than cars (even loaded oil tank cars) if the brakes went at the end of the train away from the engines first, momentum from the load would have pulled the train down the hill toward the town; if the cars didn't destroy the tracks derailing (ie if there was track left at all) the engines are enough heavier to stay on the rails -- and then it's a matter of the engines rolling to the end of their momentum.

      Watch a pendulum wind down sometime.

      LBJ, Van Cliburn, Ike, Wendy Davis, Lady Bird, Ann Richards, Barbara Jordan, Molly Ivins, Sully Sullenburger, Drew Brees: Texas is NO Bush League!

      by BlackSheep1 on Thu Jul 11, 2013 at 01:45:42 PM PDT

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