The Class 313 is a type of dual-voltage electric multiple unit (EMU) train built by BREL York Works between February 1976 and April 1977. They were the first second-generation EMUs to be constructed for British Rail and the first British Rail units with both a pantograph for 25 kV AC overhead lines and shoegear for 750 V DC third rail supply.includeonly> They were the first units in Britain to have multi-function Tightlock couplers, allowing coupling and the connection of control electric and air supplies to be carried out from the cab.