Prior to the arrival of the day's first steam locomotive at Alresford this Class 08 shunter shifted carriages about to make up a consist for the first engine's arrival. Notice the coupler systems employed on the shunter and the carriage to the left. A knuckle coupler here is called a "Buckeye" coupler. It is designed to swing down out of the way so that the typical English buffers and screw coupling, as seen on the shunter, can be utilized. And don't forget, we're using vacuum brakes systems here too.