Here’s the scenerio: Train coming from track speed of around 50mph to pull into a 20mph switch. Train is down to “18-20mph” with the “dynamics in 4” with “no brake application prior or at all” also with “no slack action felt”. The train came apart 77 cars deep of about 120 cars. Conductor went back and inpected the car and there was nothing broken. “The pin just came open with no damage” (words in parentheses were from the train crew).
What would cause this seperation of train? From what I gathered is that bad train handling isn’t a factor.
Based on what info you provided, with the dynamics on and no train line application, the slack would have run in, all the cars would have been bunched up and any dip in the track or roadbed could cause the knuckles to slip up or down enough to come apart.
Beyond that, again with out having been there, its just guessing.
At the parting…was the knuckle on one of the cars open, or were both knuckles closed?
A knuckle open would indicate a car with a suspect coupler locking mechanism.
Both knuckles closed would indicate a ‘slip over’ where because of track irregularities and a bunched slack condition one knuckle was able to ride up and over it’s partner on the adjoining car.
If a knuckle was shattered it would be a train handling situation.
The knuckle was open. The train backed up, made the joint and proceeded into Neenah and made its set out, pick up and took off. The uncoupling was between 2 GTW series steel coil cars. Couplers were perfectly aligned as it went by us.
How does coupler mechanism work and how could it fail. I am assuming that the car was handled farther south than Fond du Lac (30 miles from where it came apart) since it was the 7th car out of 9 all GTW loaded steel coil cars.
I’m just miffed at this. I’ve seen broken draw bars, broke and shattered knuckles, slip-overs but never heard or seen a knuckle just opening up.
Strange stuff happens. The train never made a stop, so that rules out extracurricular help from the local populace. Something just caused the pin lifter to actuate, I guess.
It’s not really that rare to have a pin lifter open up a knuckle. Auto racks seem to be more prone to this. This may be due to the long cushioned drawbars, something that many coil steel cars also have.
Just speculation, but the cut lever that goes to the knuckle on these extended drawbars isn’t one piece. The two pieces can slide making the lever longer or shorter slide as the slack adjusts. If the two pieces bind so they can’t slide when the slack comes in, they may push the pin up, releasing the knuckle.
It happens to other cars without the extended drawbars too, but doesn’t seem to be as often. As I said, just speculation. I’m not a car man.
This actually just happened to a buddy of mine. He was in the trailing unit and all of a sudden they went into emergency. He looked back and the train was gone! He then saw the rest coming right at him! He was more than a little scared, but everything stayed on the rails and nothing broke, thank god. No idea how it happened.
Anti-creep is the gap bewtween the uncoupling lever and the lock lifter under the coupler , The gap per the FRA is a minium of 1/4 " inch . If it is less than that any slack action can cause the uncoupling lever to push up the lock lifter and open the knuckle .
The lack of a gap could be caused from a bent or woen uncoupling lever .
It’s not the most uncommon thing to happen, despite all the remarks of mystification I see here. It’s true that sometimes the knuckle comes open, it is either that the pin has not completely fallen, despi,te all appearances to the contrary, or the cut lever somehow has bounced, no idea why.
What we used to call bouncing in two used to be not unterribly uncommon on rough track and there was always the high-low drawbar situation that used to happen.