On any British Rail standard coaching stock when one coach is coupled to another this uses "buck-eye" semi-automatic couplers (semi-automatic because the buck-eye only makes up the physical connection between one vehicle and another, as opposed to a "true" automatic coupler which also connects brake/multiple working controls/electrical jumpers a la
DMUs▸ ). The gangways themselves act as the buffers between vehicles, with the "normal" buffers retracted out of use.
When a carriage is coupled to a locomotive with a screw coupling, the buck-eye swivels down out of use to reveal a standard coupling hook. The buffers are pulled out of the coach body and a "saddle" placed on top of the shank to keep them extended. The coupling is screwed up tightly to ensure that the buffers are in contact the whole time to ensure a comfortable ride.
Diagrams here that might make things clearer...
http://www.norgrove.me.uk/buckeye.htmScrew couplings are still widely used on goods stock, but all but extinct on passenger vehicles except when loco-hauled. They are pretty common in mainland Europe though.
Buckeyes weigh about 14 stone, so lifting them up from the "out of use" to "in use" position isn't trivial. It's especially difficult if you're not the right height... I'm lucky because the coupler rests nicely on my forearm whilst pinning it in place but shorter people can have a real struggle.
BR▸ required guards to be able to lift buckeyes as part of their shunting training, which is one of the reasons why the first female guard was not employed until the late 1970s; see
http://hastingspress.co.uk/railwaywomen/gd1.html. I'm not sure if guards are still required to be competent in shunting using buckeyes or not currently.
Here endeth the lesson...