British Rail Class 120

British Rail Class 120
Swindon 3-car Cross-country sets
British Rail Class 120; Swindon 3-car Cross-country sets
In service	1958–1989
Manufacturer	British Railways
Order no.	30334 (50647-50695); 30335 (50696-50744); 30336 (59255-59301); 30515 (51573-51581); 30516 (51582-51590); 30517 (59579-59588); 30559 (51781-51787); 30560 (51788-51794); 30561 (59679-59685);
Built at	BR Swindon Works
Family name	First generation
Replaced	Steam locomotives hauling auto coaches and coaches
Constructed	1957–1960
Number built	194 cars
Number preserved	1 car (a TSLRB)
Number scrapped	193 cars
Formation	3 car sets: DMSL-TSL[RB]-DMBC
Diagram	DP204 or BR586; DP205 or BR637; DQ101 or BR587; DQ303 or BR587; DQ304 or BR636; DT210 or BR572; DT217 or BR561;
Fleet numbers	51573-51581, 51781-51787, 53696-53744 (DMBC); 59255-59301, 59579-59588, 59679-59685 (TSLRB); 50647-50695, 51582-51590, 51788-51794 (DMSL);
Capacity	DMC: 18 first class and 16 second class seats; DMSL: 68 second class seats; TSLRB: 60 second class seats; TSL: 68 second class seats;
Operators	British Rail
Depots	CA Cambridge; CF Cardiff Canton; CH Chester; DY Derby Etches Park; HA Haymarket; LA Laira; RG Reading;
Lines served	Halwill Junc - Wadebridge; Par - Newquay; St Erth - St Ives; Truro - Falmouth; Truro - Newquay;
Specifications
Car body construction	Steel
Car length	64 ft 7+7⁄16 in (19.70 m) (DP205, DQ304, over body); 64 ft 6+1⁄8 in (19.66 m) (others, over body);
Width	9 ft 3 in (2.82 m) (overall)
Height	12 ft 9+1⁄2 in (3.90 m) (overall)
Doors	Slam
Wheelbase	46 ft 6 in (14.17 m) (bogie centres); 8 ft 6 in (2.59 m) (bogies);
Maximum speed	70 mph (113 km/h)
Weight	Dia 586: 36.50 long tons (37.09 t; 40.88 short tons); Dia 587: 36.35 long tons (36.93 t; 40.71 short tons); Dia 561: 30.60 long tons (31.09 t; 34.27 short tons); Dia 636: 36.95 long tons (37.54 t; 41.38 short tons); Dia 637: 37.05 long tons (37.64 t; 41.50 short tons); Dia 572: 30.15 long tons (30.63 t; 33.77 short tons);
Prime mover(s)	Two BUT (AEC) of 150 hp (110 kW) per power car
Power output	600 hp (447 kW) per 3-car set
Transmission	Standard mechanical
HVAC	Oil burning air heater
Bogies	DD1 mk1 and mk2 (one of each); DD2 mk1 and mk2 (one of each); DT3 mk1 and mk2 (one of each);
Braking system(s)	Vacuum
Safety system(s)	AWS
Coupling system	Screw
Multiple working	■ Blue Square
Track gauge	4 ft 8+1⁄2 in (1,435 mm)

The British Rail Class 120 was a cross-country DMU in three-car formation, built at the British Rail Swindon Works.