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Old 13th July 2017, 22:32   #631
Far north 37
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May have been asked before, but whilst it was diesel only on this occasion, are the 88s able to have both modes providing power at once? Or is it once or the other?
id imagine there set up to take power from one or the other it would be a lot more complex on the techincal side to have both running at the same time surely im not sure where they would need to combine them they surely both run of different systems which they switch to as and when required combining them would just over complicate things i might be wrong though.
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Old 13th July 2017, 22:57   #632
TimboM
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id imagine there set up to take power from one or the other it would be a lot more complex on the techincal side to have both running at the same time surely im not sure where they would need to combine them they surely both run of different systems which they switch to as and when required combining them would just over complicate things i might be wrong though.
Yes, that's my thoughts - too complex and why would you need it anyway (or at least need it enough to overcome the complexity/cost).

But would be good if someone could confirm for definite.
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Old 13th July 2017, 23:00   #633
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Yes, that's my thoughts - too complex and why would you need it anyway (or at least need it enough to overcome the complexity/cost).

But would be good if someone could confirm for definite.
yeah be nice to have it confirmed impressive pulling power on diesel though in the video

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Old 14th July 2017, 06:44   #634
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It is possible to use both modes at once if required but when about to move away from the wires the pantograph must be lowered. This ability gives it extra power if needed. Probably also a factor included in its permission to run over the mountains on its own provided the load does not exceed 1800 tons.
The new Euro dual, currently under test in Romania, has around 11,000 horses available when both modes are used at once. 10 have already been ordered for a German user HVLE.
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Old 14th July 2017, 08:20   #635
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At low speeds the locomotive power output is limited by tractive effort. (power output = tractive effort X speed) It is not until the train is doing at least 40mph would there be any benefit from starting the diesel.
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Old 14th July 2017, 09:28   #636
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At low speeds the locomotive power output is limited by tractive effort. (power output = tractive effort X speed) It is not until the train is doing at least 40mph would there be any benefit from starting the diesel.
You are talking about power at the rail/wheel rim interface, which does not equate to prime mover power from whatever source. Prime mover power has to include not just power to traction motors but also power for on-board services and ancillary uses within the locomotive itself. The additional power from both modes together is used to improve acceleration and maintain higher speeds with heavy loads. I can ask later to see if diesel power is used on the class 88 on service trains while on electric power or only when changing oer to leave the wires. Changeover is done while moving.
FYI the starting tractive effort of the class 88 is the same in both diesel and electric mode even though the HP figures are 975 vs 5000+.

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Old 14th July 2017, 10:04   #637
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Originally Posted by Sunbird24 View Post
It is possible to use both modes at once if required but when about to move away from the wires the pantograph must be lowered. This ability gives it extra power if needed. Probably also a factor included in its permission to run over the mountains on its own provided the load does not exceed 1800 tons.
The new Euro dual, currently under test in Romania, has around 11,000 horses available when both modes are used at once. 10 have already been ordered for a German user HVLE.
I am sure the 5000+ horses available in electric mode are quite sufficient to power 1800t trains over the northern fells.

I remain to be convinced about adhesion in poor conditions, which the addition of more horses at the wheelrim will do nothing to solve.
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Old 14th July 2017, 12:51   #638
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The ability to run into non-electrified yards must save time =money. Any insider know how much?
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Old 14th July 2017, 14:46   #639
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The ability to run into non-electrified yards must save time =money. Any insider know how much?
I expect the bigger saving is not running the train for hundreds of miles on diesel under the wires (with the cost of fuel) or not having to do a shunt to put a diesel on the front near the end (where yes, time is going to dominate I'd expect).
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