| British Rail Class 123 | |
|---|---|
 A mixed four car DMU stands at Manchester Piccadilly in 1984. The two driving coaches are from a class 123 and the middle coaches are from class 124 units. | |
| In service | 1963–1984 |
| Manufacturer | Swindon Works |
| Family name | First generation |
| Replaced | Steam locomotives and carriages |
| Scrapped | 1984–1987 |
| Number built | 40 (Ten 4-car units) |
| Number scrapped | All |
| Formation | DMBSL-TCK-TSL[RB]-DMSK |
| Capacity | 24 First class, 176 Second class seats (units with buffet 32 second class less) |
| Operator | British Rail |
| Depots | |
| Lines served | Western Region Eastern Region |
| Specifications | |
| Car body construction | Steel |
| Car length | 64 ft 11+1⁄4 in (19.793 m) |
| Width | 9 ft 3 in (2.82 m) |
| Height | 12 ft 9+1⁄2 in (3.899 m) |
| Maximum speed | 70 mph (113 km/h) |
| Weight | 146.75 long tons (149.10 t; 164.36 short tons) |
| Prime movers | 230 hp (172 kW), 2 per power car |
| Power output | 920 hp (686 kW) |
| Bogies | B4 |
| Multiple working | Blue Square |
| Track gauge | 4 ft 8+1⁄2 in (1,435 mm) |
The British Rail Class 123 was a design of diesel multiple unit built for British Rail in 1963. They were the last first-generation DMUs built for British Railways and were built at Swindon Works. Ten of the four-car sets were built and introduced in 1963. The units bear a visible similarity to the British Rail Class 309; however, there is no 'relation' here as the two types were built by different manufacturers for different markets.
