Southern Electric Locomotives

This article first appeared in the March 1989 issue of BRMA's 'Clearing House'.
by 'Electron'

There have been 76 electric locomotives to run on the southern region. The first two of these were built by Southern Railways in 1941 and 1943 respectively based on a design by the Southern's electrical engineer Alfred Rawood.

These two locomotives (originally numbered CC1 and CC2 and renumbered 20001 and 20002 by British Railways on nationalization) were joined in 1949 by a third locomotive of similar design (20003). These three locomotives survived until 1969 and were occasionally used in their day to haul royal trains. The locomotives were allocated TOPS class 70 numbers but the locomotives were scrapped prior to the numbers being applied.

A number of different colour schemes were applied to the 70 class locomotives. CC1 started life in workshop grey with three white lines down the side. It was soon repainted in malachite green with yellow lining which was the colour that the other two 70 class locomotives first appeared in. 20002 was repainted Wedgewood blue after nationalization. All three were then painted black with silver lining then repainted in malachite with red and white lining (which was soon removed) before finally appearing in rail blue with yellow ends.

The 70 class locomotives were designed to operate via a third rail pickup for normal operation but the dangers of laying live third rails in goods yards led to the locomotives also being fitted with pantographs and light tram-type catenary being fitted over yard tracks. The locomotives were designed to operate from a 660 volt DC supply which the Southern Railways (or rather its predecessor the LSWR) had been using for their EMU supply since 1913. The line voltage was increased by BR in 1955 to 750 volts. Two booster generator sets (flywheel driven generators) were provided in each locomotive to enable it to maintain movement over the necessary rail breaks associated with pointwork.

Southern Railways had intended building a larger number of these locomotives (whose appearance led to them being given the nickname 'Hornby') but Nationalization intervened and while construction of the third locomotive (which was already underway) was completed no further locomotives of this type were built and it was almost another ten years before a fourth electric locomotive was built for the southern region.

 

The increase in the rail voltage from 660v to 750v was associated with the Kent Coast electrification process. A second generation of SR electric locomotives (13 initially, later expanded to 24) were built between 1958 and 1960. These locomotives were originally numbered E5000 - E5023 but E5000 was soon renumbered as E5024.

In 1968 fourteen of these locomotives were designated as TOPS 71 class the other ten being rebuilt into 74 class electro-diesels at about that time.

The locomotives were originally painted green with a red and white waist line (soon painted out and yellow warning panels added) and were eventually repainted in blue and yellow.

The booster system of the 70 class was retained (although now reduced to one set per locomotive), as were the third rail and overhead pickups. A lack of steam heating in these locomotives saw them in 1964, double heading trains with a standard class 5 steam locomotive. The electric train heating with which the locomotives were fitted could not be used because of a lack of suitable stock.

Problems were experienced with the pantographs on these locomotives. The pantographs had a tendency to spring up at the most awkward moments. E5009 lost its pantograph at Petts Wood on 13th April 1964 when it sprang up just before the locomotive passed under a foot bridge.

The locomotives were scrapped in 1977 as part of BR's rationalization plan. 71001 has been preserved by the National Railway Museum.

 

The 73 class locomotive has its roots in 1930 when Southern Railways began investigations into the possibility of a dual powered locomotive. Both diesel and battery power had been investigated for the 70 class before being rejected in favour of the booster system. Other alternatives were investigated and attempts made to design a locomotive which had equal power on either electric or diesel power.

Design of what was to become the 73 class began in 1956 and construction of the first six commenced in 1959. No attempt was made to give the locomotives equal power in both modes and whereas the locomotives have 1600hp when running on electric power, only 600hp is available on the unelectrified lines.

The locomotives are designed to be mixed traffic engines but the resultant reduction in power when leaving the electric network means that (apart from shunting duties) the 73 class are usually used only on passenger trains, when on unelectrified lines.

A further 30 locomotives of slightly different design were soon ordered and then yet another 13. The original six were originally allocated TOPS class 72 with the later 43 being allocated to class 73 but these were changed to 73/1 and 73/2 respectively in 1969 and again in 1974 to 73/0 and 73/1.

The first of the 73/0 class locomotives originally appeared in plain malachite green with yellow warning panels , but some grey lining edged with white was soon added (and the warning panels removed). The remaining five of the original batch then appeared in a similar colour scheme.

The 73/1 locomotives began life wearing rail blue and yellow and were one of the first classes of locomotive so painted. Almost all of the 73 class locomotives are still in service and a number of different colour schemes have been applied to them in recent years.

No pantographs or boosters are fitted to the class 73s since the locomotives are capable of shunting on diesel power. Momentum is relied upon to get the locomotive across rail-breaks and if the locomotive does stall on the gap a few minutes can see it back on the rail through use of its diesel engine. Resistance controls are fitted to the class 73s of a type similar to that fitted to the various southern EMU stock.

 

A new 3000hp electro-diesel was planned for the Bournemouth line. Nothing however came of this as BR discovered that they had a number of class 71s surplus to their requirements and decided to see what could be done with those.

The class 74 locomotives were built by stripping the ten surplus class 71 locomotives down to their component parts and building a new control mechanism into the shell. At first attempts were made to work out a method of driving the booster from the diesel engine but these attempts were unsuccessful and a separate electric generator was eventually fitted and powered by a 650hp diesel engine. These locomotives were also the first on BR to be fitted with thyristor control which allowed a fully variable control instead of the stepped control when using resistors or boosters.

The 74s were originally intended to carry the numbers E7001 - E7010 but for some reason the locomotives found themselves on the track carrying the numbers E6101 - E6110. These numbers were soon changed to 74001 - 74010 when the TOPS numbering came in.

The locomotives entered operation in 1968 but suffered many breakdowns averaging only 2400km between failures during that year. Performance improved somewhat in subsequent years but never matched that of the other locomotives running on the region. The new style suspension with which these locomotives also didn't help and gave a very bumpy ride. So bumpy in fact that one locomotive bounced right off of the track.

Nine of the locomotives were scrapped in 1977, the remaining one being sent to Derby for research purposes. That last locomotive has also now been scrapped.

 

The only other locomotive to run on the Southern which falls into the category of electric locomotives was 33 class D6580 which during tests relating to the Bournemouth electrification project in 1962 was temporarily fitted with pickup shoes. It was decided, however, that the role that this modification was intended to fill could be met by the new electro-diesels and that there was also insufficient space to fit all of the necessary gear into the already crowded 33s and so the proposed conversion of the 33s did not proceed.

 

class         70        71        73/0      73/1      74
hp           1470      2552      1600      1600      2552
purpose     mixed     mixed     mixed     mixed     mixed
number built    3        24         6        43        10
number now      -         1         6        42         -
introduced   1941      1958      1962      1965      1967
withdrawn    1969      1977         -         -      1977
wheels      Co-Co     Bo-Bo     Bo-Bo     Bo-Bo     Bo-Bo
speed(mph)     75        90        80        90        90
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Copyright Stephen Chapman