Most modern tank cars like the AAR Type T104-108 I see have couplers that differ in size and shape from typical couplers found on any other type of rail car. They’re larger in size with a flat, upward vertical appendage that must have a specific purpose.
I’m interested to know what that is and why they’re only on tank cars. Can’t recall this topic ever coming up either.
Thanks
Tankcars have Type F (if I remember correctly) couplers. They are intended to keep the cars coupled to it from separating from it and puncturing it during a derailment. You should be seeing them on more thatn the T104-108 types.
If I remember correctly, those couplers were originally only required on certain tankcars but are now required on all tankcars.
They could be double-shelf E couplers instead of F. Eric’s right, though–their purpose is to prevent vertical separation of the couplers in an accident. The Type F cars give a tighter joint; they also have appurtenances on the side.
You’ll also find F couplers on unit coal trains, where rotary couplers might increase the possibility of an undesired vertical separation.
…Am I remembering correctly that passenger cars have a type of coupler to keep the cars together even during derailing too, etc…
Your memory serves you well. Passenger cars are equipped with Type H Tightlock controlled slack couplers.
Is this a cause because of those couplers as in many other tank cars derailing? If I remember correctly, there was over 75 tankers that tipped over besides the ones that are piled up in the picture. Clara City Minnesota. Not my photo, from a newspaper.
…Thanks for confirm Paul.
My recollection is that it was an FRA or AAR requirement for tank cars hauling combustible or hazardous materials. While the coupler is designed to not uncouple the main reason was to keep one from riding up and puncturing the end of the tank. In addition to the coupler the tank ends were beefed up to help prevent penetration also. There were also a couple of related improvements beside those two. It was well covered and I believe there was a Trains article back at the time covering the changes and the reasoning.
…Believe some tanks got a sort of shield in the coupler area.
Double shelf couplers on all tankcars is an FRA mandate. It’s purpose is to prevent tankcars from uncoupling from each other in the event of a derailment, and then having one coupler ride up and into the tank head of an adjacent tankcar. This would result in a loss of product. The theory is, have all attached cars derail (i.e. roll over), rather than one car derail, and the next one puncture it. If you’ve seen any of the photos in the news from the Colorado tornado a few weeks back, you’ll see a line of tankcars rolled over. This is an example of the double shelf coupler in action. I’ve also seen some hoppers equipped with double shelf couplers, but this is more likely just a case of availability rather than a more widespread use of these couplers.
I’ve seen UP orders of covered hoppers with bottom-shelf E couplers specified.
Here is a link to a story about an accident in Decatur IL http://findarticles.com/p/articles/mi_qa3945/is_200409/ai_n9419936/pg_1 in 1974, I think this was one of the accidents that brought the coupler changes to tank cars. In this case a car coupler rode up over tank car and ruptured the tank starting a tragic series of events which claimed the lives of 7 railroad employees.