Railway vehicle; Circle Line C-stock driving motor car 5721, 1977

This car is a C77 stock car designed for sub surface lines with high volume passenger numbers and short journey lengths. The high-density nature of the Circle line service meant that loading times were important; consequently all cars were fitted with four double sets of air-operated sliding doors per side. Seating was mainly transverse, and total seating capacity was 32 per car.
The C77 had some technical upgrades but was compatible with earlier C69 stock and was used on the Circle, District and Hammersmith & City (formerly Metropolitan) lines between 1970 and 2014.
The original C69 stock was constructed using a load-bearing aluminium underframe with a non-load-bearing body of riveted panels on aluminium framing.
The C77 stock was identical in terms of layout and could run with C69 stock even though there were some technical differences between them. Equipment as built included load sensing "Metacone" air suspension, rheostatic braking, hydraulic parking brake, pneumatic camshaft control by GEC and Brush DC motors of type LT117, with each DM car having four motors . Air supply was by Reavell reciprocating compressors and braking equipment was by Westinghouse. The guard's door controls were in the driver's cab; this eased conversion to one-person operation in 1984, the first LU line to do so. After refurbishment works in 1991 and 1992 there were no visual differences between the stocks.
The C77 stock were replaced by the S7 Stock between 2012 and 2014.