Class 73
 photograph by Ray Soper E6013, later to become 73110, photographed at Wimbledon on 16th November 1966 |
| The Class 73 is almost unique on British Railways today
in that it is capable of being powered by two different sources - traction
current picked up from the third rail and also from its on board diesel
generator set (albeit at reduced power). As such it is termed an
"electro-diesel" (EDL). There was one other electro-diesel type - the
class 74 - a later conversion from pure electric
locomotive class 71 which was not a success and
all have been withdrawn. (The class 92 and class 319 are also dual powered
locomotives - but in this case both supplies are electric - 25kV ac overhead
and 750V dc third rail.)
This flexible dual power concept was first considered immediately post World War II as a solution of how to make the most of the Southern's expanding electrified system by permitting working with the same locomotive on non electrified lines in otherwise electrified territory, also on non electrified sections in sidings and when the traction current was switched off during engineering work, etc. Perhaps the electro-diesel concept was copied from the contemporary General Motors FL9 locomotive, but there is a significant difference in that the FL9 is designed and operated with the reverse requirement. That is as a full power diesel-electric locomotive for the majority of the time and only working on electrical pick up on comparatively short stretches of track, mainly the tunnels under the Hudson and East Rivers (where for many years steam/diesel locomotives were prohibited) to gain access to Grand Central Station on Manhattan Island. Also the Southern had its own experience in maintaining electrical drive - albeit only over short gaps in the third rail - with its pure electric "booster" locomotives CC1-3, later class 70. |
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Class 73 E6036 arriving at Clapham Junction with a 4TC on
21st November 1966. D5409 alongside brought in a milk train and is now
departing light engine.
photograph by Ray Soper |
| The same loco and trailer unit a few moments later.
photograph by Ray Soper |
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E6046 at Clapham Junction during November 1966.
photograph by Ray Soper |
| E6039 heads a goods working through Clapham Junction.
photograph by Ray Soper |
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This page was last updated 11 June 2005
