the british rail class 506 was a 3 carriage electric multiple unit (emu) built for local services between manchester, glossop and hadfield on the woodhead line. the 8 units were introduced in 1954. they had air-operated sliding doors. the emus had a single diamond-shaped pantograph, mounted over the driver's cab and adjacent guard's compartment at the outer end of one of the driving carriages (unlike other british emus, where the pantograph is mounted over one of the middle carriages).