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Class 81 on the GE?


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Ok so i don't think it ever happened, which is a pity.  But I can't help thinking that with the 6.25kV capability of the class it would have been worthwhile building an extra 20 or so class 86's and transferring the entire class 81 fleet to the GE in the sixties.  All services could then be Electric as far as Colchester, eliminating fumes from Liverpool Street.  Not only that but they would flatten Brentwood Bank, as well as being able to take full advantage of the 100mph undulating section between Chelmsford and Colchester, which at the time only the Class 309 could make use of.  It would also have the advantage of eliminating a class from the WCML, simplifying maintenance and spares requirements there.  They would have cost far less to run than Class 47's although of course some would still be required for the Colchester-Norwich section as well as freight.  Infrastructure changes would have been minimal, if any - probably servicing the class at either Ilford or Colchester to avoid having to put wires into Stratford.

 

I wonder if it was ever considered?

Edited by Titan
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29 minutes ago, Titan said:

Ok so i don't think it ever happened, which is a pity.  But I can't help thinking that with the 6.25kV capability of the class it would have been worthwhile building an extra 20 or so class 86's and transferring the entire class 81 fleet to the GE in the sixties.  All services could then be Electric as far as Colchester, eliminating fumes from Liverpool Street.  Not only that but they would flatten Brentwood Bank, as well as being able to take full advantage of the 100mph undulating section between Chelmsford and Colchester, which at the time only the Class 309 could make use of.  It would also have the advantage of eliminating a class from the WCML, simplifying maintenance and spares requirements there.  They would have cost far less to run than Class 47's although of course some would still be required for the Colchester-Norwich section as well as freight.  Infrastructure changes would have been minimal, if any - probably servicing the class at either Ilford or Colchester to avoid having to put wires into Stratford.

 

I wonder if it was ever considered?

Wasn't it considered later on, when the Class 47/7 push-pull system was being developed as the system had an equivalent function for 81s though it was never used as such. That would probably have been more when they were planning the through electrification in the 1980s we have now though.

 

As to introducing 81s on the GEML in the 1960s after the 86s were built, while perhaps a small consideration - linespeed was only 90 not the full 'ton' until 1970 as I recall, when it was raised to 100.

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Until Liverpool Street was rebuilt/desecrated the one or two loco hauled services an hour to Norwich and Kings Lynn had no real impact on air quality. As they found when did loco changes at Cambridge and Ipswich even the slickest loco change would wipe out any reduction in journey time from extra 1000hp+ a Class 86 could provide (as said top speed was irrelevant it was ability to accelerate which was improved). They only did it for mileage accumulation under the wires and to release some of the SF 47/4s. Also doing loco changes on the up line at Colchester would have been a nightmare; the benefit if both Cambridge and Ipswich is that they had convenient crossovers, (in the station or south of the tunnel). 

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