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Yes, the Re465s are more powerful than the Re460s.
by jfbeaulieu on Tue Jul 7th, 2009 at 10:14:04 AM EST
[ Parent ]
That increased power was mainly due to other improvements, but, under ideal weather conditions, the Re 465 also have more stable adhesion, resulting in a higher maximum tractive effort. (Power difference: 4.8 vs 6.27 MW continuous, 6.1 vs. 7MW one-hour rating; tractive effort: 300 vs. 320 kN.) Then again, that's ideal weather conditions -- I am not surprised to find that train weight limits are the same.

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Tue Jul 7th, 2009 at 11:08:28 AM EST
[ Parent ]
I don't have the weight for a Re465, but if it weighs 85 tonnes, then your wheelslip system needs to achieve a factor of adhesion of 38% to produce 320kN of pull, or 36% to produce 300kN. The later figure is reasonable, while the former is possible but has significantly larger risks, especially where delays caused by a stalled train cause cumulative delays to the whole system.
by jfbeaulieu on Tue Jul 7th, 2009 at 10:53:40 PM EST
[ Parent ]
Given that 38% can drop to 20% in rain (or when a snail climbs across the rails), I submit this whole maximum adhesion idea was moot.

(Weights: I have 84t vs. 82.5t, so it is even lighter - 320 kN giving 39.5% adhesion.)

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Wed Jul 8th, 2009 at 08:35:11 AM EST
[ Parent ]
A drop from 38% to 20% solely due to rain is a terrible performance, and not indicative of a very sophisticated adhesion management system. Both EMD and GE for their modern diesels use a "Creep Control" system to achieve maximum adhesion whereby at speeds above 7 mph. wheel rotation is 7% faster than needed for the current ground speed, also the control computer will reduce power slightly to the leading axle to allow it to "Dress" the contact surface of the rail and eliminate material such as oil or squashed insects (caterpillars and locust are the worst) before the other axles pass. The much greater weight of North American diesels probably is high enough to break the surface tension of most materials likely to be found coating the rails which would help also.
by jfbeaulieu on Wed Jul 8th, 2009 at 01:36:07 PM EST
[ Parent ]
I didn't mean to include EMD in the part concerning lower power supplied to the lead axle, as since EMD lacks single axle control there is no way they could do that.
by jfbeaulieu on Wed Jul 8th, 2009 at 02:51:39 PM EST
[ Parent ]
"Dress" = cleaning creep (that's how I translate German Putzschlupf; I don't know if there is a British -> UIC English term) is a real benefit of single axle control - and an advantage of the 'rail-tearing' axle-hung motor Siemens EuroSprinters over the present Bombardier TRAXX locos. (There have been two major comparison tests I read of, one on the steep line to Blankenburg/Harz in Germany with its isolated 25kV/50Hz electrification, another on the Brenner route, with a DB 189 = ES64F4 coming out on top in both cases.) However, on four rather than six axles, that's still a 25% drop in adhesion. (Note that on the aforementioned Blankenburg line, the isolated electrification was dismantled in the end, and six-axle diesels took over.) Then there is sanding (and with that increased sand use and track/wheeltread wear), but that is not always stable, in particular for all four axles. There is also the cleaning brake block - which is not widespread enough across Europe for reasons that appear bureaucratic to me. And, as you say, axle weight is a third of the US, so it's all less stable. (Though still less bad for locos than for even lighter EMUs and DMUs.)

Wheel slip is just a notorious problem even with cleaning creep, sanding and cleaning brake blocks -- softwares are updated repeatedly, and they get national versions.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Wed Jul 8th, 2009 at 04:18:08 PM EST
[ Parent ]

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