High Quality Content by WIKIPEDIA articles! British Rail Class 313 electric multiple units were built by BREL at York Works between February 1976 and April 1977 and were the first second-generation EMUs to be constructed for British Rail. They were also the first British Rail units fitted with both a pantograph for 25 kilovolt AC overhead lines and shoegear for 750 volt DC third rail supply, and the first units in Britain to have Multi-Function couplers, which allow both physical coupling and also the connection of control electric and air supplies to be carried out without the need to leave the cab. After the withdrawal of most first-generation stock, they are now the oldest EMUs in regular service on the UK mainland`s rail network; as of 2012, the youngest class 313 unit is now 35 years old.