class37418stag Posted April 11, 2018 Share Posted April 11, 2018 Hello everyone I has read information about class 71 later rebuilt class 74 but class 71 & class 74 was more powerful than class 73 Why BR ordered class 71 & 74 to scrap as withdrawn over what ? Too noise engine as running line by through the night by while resident can’t sleep OR Poor maintenance OR Few times by broken down by problem of engine Thank you Link to post Share on other sites More sharing options...
woodenhead Posted April 11, 2018 Share Posted April 11, 2018 The Class 71 came first to run express services between Victoria and the Kent coast plus freight work. However some became surplus to requirements as worked dried up and BR needed more Electro-diesels so some were converted to Class 74 to work Southampton and Weymouth boat trains which need motive power off the electric network. Eventually all became redundant because of further reductions in work for them and the 73 was more a more flexible package and they also had plenty of class 33s. Link to post Share on other sites More sharing options...
SRman Posted April 12, 2018 Share Posted April 12, 2018 The Class 71 came first to run express services between Victoria and the Kent coast plus freight work. However some became surplus to requirements as worked dried up and BR needed more Electro-diesels so some were converted to Class 74 to work Southampton and Weymouth boat trains which need motive power off the electric network. Eventually all became redundant because of further reductions in work for them and the 73 was more a more flexible package and they also had plenty of class 33s. Adding to that, the 74s had more powerful diesel engines than class 73, from Paxman, but these and all the new electronics used made them rather unreliable. Class 71s were acknowledged as very good locomotives but the work dried up (as stated above) and the 71s were too inflexible as straight electrics; if the power was turned off for maintenance works, they had to be rerouted by sometimes long and torturous routes to get to their required destinations. Electro-diesels had no such restrictions. It was eventually decided that class 73 could do most of the work that was required from classes 71 and 74. Link to post Share on other sites More sharing options...
Wickham Green Posted April 12, 2018 Share Posted April 12, 2018 (edited) Adding to that, the 74s had more powerful diesel engines than class 73, from Paxman, but these and all the new electronics used made them rather unreliable. Class 71s were acknowledged as very good locomotives but the work dried up (as stated above) and the 71s were too inflexible as straight electrics; if the power was turned off for maintenance works, they had to be rerouted by sometimes long and torturous routes to get to their required destinations. Electro-diesels had no such restrictions. It was eventually decided that class 73 could do most of the work that was required from classes 71 and 74. Yes, the electronics were rather ahead of their time and - like most new technology - didn't take well to a railway environment ......... otherwise the 74s were a logical development of the 71s with the flexibility of the 73s which didn't need overhead wiring of the freight yards - but the drop-off in freight traffic rendered anything non-standard redundant. Oh - perhaps the topic should be re-titled to Electro-Diesel ??!? Edited April 12, 2018 by Wickham Green Link to post Share on other sites More sharing options...
RMweb Gold TravisM Posted April 12, 2018 RMweb Gold Share Posted April 12, 2018 From what I remember reading previously, the 10 Class 71's that were used for the rebuild into Class 74's were in the worst condition of the original 24 and were in dire need of rebuilding anyway; and the remaining 14 were renumbered back into the original E5000 series rather than leaving gaps in the numbers. I also recall that Crewe works had issues rebuilding them, took longer than planned and the build quality was questionable. Also there were issues with the Paxman engines, electronics which others mentioned. I think the overall plan was to see if the first batch were successful, was to rebuild the rest but with traffic falling especially coal and ferry traffic on the eastern section and boat traffic on the western, the Southern Region found itself with plenty of surplus Class 33's and 73's, so both classes were withdrawn. Link to post Share on other sites More sharing options...
slilley Posted April 12, 2018 Share Posted April 12, 2018 (edited) There is a book on the Class 71s & 74s that came out last November, Southern Way Special No 14. Published by Crecy Publishing in Manchester. All you need to know about both classes. http://www.crecy.co.uk/the-southern-way-special-no.-14 Best wishes Simon Edited April 12, 2018 by slilley Link to post Share on other sites More sharing options...
RMweb Premium keefer Posted April 14, 2018 RMweb Premium Share Posted April 14, 2018 (edited) i'm not 100% on the details but I think the 74 differed in how the diesel engine powered the loco. whereas the 73 was fairly conventional in having the engine revs drive the generator according to demand, the 74s engine ran at constant revs so the generator provided a constant 750V supply - this was then controlled using the circuitry and control systems. The diesel/generator output was effectively a 'replacement' supply of the line voltage otherwise available from the 3rd rail. i.e you had an electric loco with an alternative power source on board, whereas the 73 is more like an electric and diesel-electric loco in the same body Edited April 14, 2018 by keefer Link to post Share on other sites More sharing options...
009 micro modeller Posted April 14, 2018 Share Posted April 14, 2018 the 71s were too inflexible as straight electrics. Didn't they also have the disadvantage of having to have small pantographs fitted and tram wires in yards, whereas electro-diesels just run on diesel mode in places where the third rail would be unsafe? Link to post Share on other sites More sharing options...
slilley Posted April 15, 2018 Share Posted April 15, 2018 i'm not 100% on the details but I think the 74 differed in how the diesel engine powered the loco. whereas the 73 was fairly conventional in having the engine revs drive the generator according to demand, the 74s engine ran at constant revs so the generator provided a constant 750V supply - this was then controlled using the circuitry and control systems. The diesel/generator output was effectively a 'replacement' supply of the line voltage otherwise available from the 3rd rail. i.e you had an electric loco with an alternative power source on board, whereas the 73 is more like an electric and diesel-electric loco in the same body Thats the basics of it. Explained in more detail in Southern Way Special No 14. Didn't they also have the disadvantage of having to have small pantographs fitted and tram wires in yards, whereas electro-diesels just run on diesel mode in places where the third rail would be unsafe? The Class 71s were pantograph fitted for work in certain yards. max speed under the wires 15mph Link to post Share on other sites More sharing options...
SRman Posted April 16, 2018 Share Posted April 16, 2018 Didn't they also have the disadvantage of having to have small pantographs fitted and tram wires in yards, whereas electro-diesels just run on diesel mode in places where the third rail would be unsafe? There were pantographs fitted but they weren't small. The use of overhead wiring in certain yards was instead of third rail, and was for the safety of the men working on the ground in those yards. Link to post Share on other sites More sharing options...
RMweb Gold The Johnster Posted April 16, 2018 RMweb Gold Share Posted April 16, 2018 Thats the basics of it. Explained in more detail in Southern Way Special No 14. The Class 71s were pantograph fitted for work in certain yards. max speed under the wires 15mph 15mph is the normal maximum speed in yards and other non-running lines anyway. Link to post Share on other sites More sharing options...
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