British Rail Class 70 (electric)

Southern Railway Class CC Electrics British Rail Class 70
20002 at the Eastleigh Works Open Day in August 1964
Type and origin Power type Electric Builder SR Ashford Works (2) BR Brighton Works (1) Build date 1941, 1945, 1948 Total produced 3
Specifications Configuration: ​  • UIC Co′Co′  • Commonwealth Co-Co Gauge 4 ft 8 1⁄2 in (1,435 mm) standard gauge Wheel diameter 3 ft 6 in (1,067 mm) Loco weight 20001/2: 99.70 long tons (101 t; 112 short tons) 20003: 104.70 long tons (106 t; 117 short tons) Electric system/s 660–750 V DC Third rail (mainline) Catenary (sidings) Current pickup(s) Contact shoe (mainline), Pantograph (sidings) Traction motors English Electric 245, 6 off Train brakes Vacuum, Air, Electro-Pneumatic
Performance figures Maximum speed 75 mph (121 km/h) Power output 1,470 hp (1,100 kW) Tractive effort 20001/2: 40,000 lbf (178 kN) 20003: 45,000 lbf (200 kN)
Career Operators Southern Railway → British Railways Class SR: CC BR: 70 Power class BR: 7P5F Numbers SR: CC1, CC2 BR: 20001–20003 Withdrawn 1968 Disposition All scrapped in 1969

The British Rail Class 70 was a class of three 3rd rail Co-Co electric locomotives. The initial two were built by the Southern Railway at Ashford Works in 1940–41 and 1945 and were numbered CC1 and CC2 - the Southern Railway latterly preferring French practice for locomotive numbers which also gave an indication of the wheel arrangement. Electrical equipment was designed by Alfred Raworth and the body and bogies by Oliver Bulleid. CC2 was modified slightly from the original design by C. M. Cock who had succeeded Raworth as Electrical Engineer. The third was built by British Railways in 1948 and numbered 20003.

Externally, it was clear that the cab design owed a lot to Southern's experience with the 2HAL multiple unit design. It has even been suggested that (in true Southern tradition) this was because the jigs for the welded cabs already existed and thus made for speedy and cheap construction! At the outbreak of war in 1939, most construction projects were put on hold in favour of the war effort. Construction of CC1 and CC2 was exempted from this, because of promised savings in labour and fuel over steam locomotives. Construction was not smooth, however, and was brought to a halt several times, due to shortage of resources. After nationalisation in 1948, British Railways renumbered them 20001 and 20002 respectively.

The third member of the class, 20003 from new, was built at Brighton. S. B. Warder (later to become Chief Electrical Engineer of the British Transport Commission and architect of the UK 25 kV AC overhead system still in use today) was, by then, Southern Railway's Electrical Engineer and he modified the design somewhat. Although counted as the same class, 20003 was markedly different externally from its two earlier sisters, being 2 inches (5 cm) longer with flat 4SUB-like cab ends, arguably simpler (and therefore cheaper) design than the earlier two. Equipment changes, though, added 5 tons to the earlier 100-ton design.