Why do European locos and rolling stock have those two elongated “bumpers” on each end? What’s their purpose? Why doesn’t North American rolling stock have them? (Or why do European rolling stock have them in the first place?)
And why don’t the European high speed trains have them?
The correct name is “buffers”. They are spring loaded to allow operation in curves and they take all the compression forces in the train. The couplings are shackles, a pair of links with screwed rods connecting them. These are screwed until there is some compression in the buffers, which takes slack out of the train. The “screw couplings” only take tension forces. These designs date back to the period of link and pin couplers in the USA, and separating tension and compression forces made the design simple.
Many European passenger trains have automatic couplers that operate like US knuckle couplers but are different in design. Most of these are made to designs by Dellner or Scharfenberg, and connect the air brakes and power and multiple unit cables as well. These do not need buffers.
Some modern trains with European automatic couplers have devices that look a bit like buffers but these are fixed ribbed panels that serve as “anti-climbers” in case of a collision.
M636C
If you turn a US car upside down you will find that it has a centre cill (spine) which surrounds the drawgears (one at each end). US drawgear deals with both tension and compression forces as the train moves.
If you turn a European or UK car with buffers upside down you will find both a pair of frame members either side of the drawgear and strong frame members down each side with a buffer beam across each end. These frames seperate out the forces.
A US frame also has what might be described as ribs extending from the main/heavy centre cill out to much lighter side cills. Eu and UK designs tend to have centre and side elements of much the same depth.
Quite a bit of modern UK stock has used “American”/ Buckeye couplers often at the ends of fixed sets with fixed bar couplings between cars in the set. Whenever we’ve tried combined coupler/pipe/control systems (Kloselock is the last I recall) they haven’t been popular and haven’t spread beyond the original units fitted with them… as far as I know these units have reverted to conventional formats but I could be wrong on this.
Any sort of “specific to stock/type” coupler is a complete pain… you can garuantee that when it conks out the next train will not be compatible and you will have to mess about with converters to get the thing out of the way. this gets worse with modern stock that has a computer in the systen that thinks that it has some idea of what it is supposed to be doing.
Great description of the differences between coupling types. Though the page is in German, you can see the three basic types in use on German railways at http://kupplung_bahn.know-library.net/. The Scharfenbergkupplung is used by railcars (primarily). The Rangierkupplung (Shunting coupler) grabs/releases the hook of the coupling on the car from the top. It is activated by the engine driver. There is also a knuckle-type coupling for use on heavy unit trains, primarily coal and ore. That can be seen at http://www.ba-bautzen.de/wirtschaftssenioren/amk/amkenglish/index.html.
Peter