Old 03-28-2009, 11:00 PM   #26
Byrnsy383
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It's not like we're talking about a corvette here, I don't see how a 4 axle can out pull a 6 with 6,000-8,000 trailing tons.
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Old 03-29-2009, 12:21 AM   #27
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Originally Posted by Byrnsy383 View Post
It's not like we're talking about a corvette here, I don't see how a 4 axle can out pull a 6 with 6,000-8,000 trailing tons.

I see what you mean! I totally phrased that wrong, what I meant was that this design offers more starting tractive effort than a conventional 4 axle ( due to the greater weight ) while still offering the same acceleration benefits of a conventional 4 axle unit. At higher speeds these units should perform pretty close to the same as a traditional 4 axle unit in terms of tractive effort and dynamic brake effort (DC traction units atleast). Also, I'll bet that GE thought ahead with this design, if it does not work as advertised they can simply make the idler axles powered! Just a guess on that last item tho.....

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Old 03-29-2009, 01:43 AM   #28
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Originally Posted by Ween View Post
Not sure...I just typey typed what was in the article.
Thanks for that.

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As far as 4-axle power on long-haul intermodal service, perhaps BNSF is hesitant after GE's B40-CW and EMD's GP60M. My understanding that both of those were rough riding and not a crew fav.
Good point. Two axle trucks weren't exactly a priority in EMD and GE, were they? Rough riding however isn't a general feature of two axles trucks - here are generally three axle trucks considered as rough riding. I suspect again that smooth riding three axle trucks weren't a priority here.

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I see what you mean! I totally phrased that wrong, what I meant was that this design offers more starting tractive effort than a conventional 4 axle ( due to the greater weight ) while still offering the same acceleration benefits of a conventional 4 axle unit.
Two questions:
1) assuming the same weight on powered axles, how can have a six axle one better starting tractive effort?
2) what acceleration benefits have conventional 4-axle units? Different transmission ratio between motors and axle?
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Old 03-29-2009, 03:48 AM   #29
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Originally Posted by dejv View Post
Thanks for that.


Good point. Two axle trucks weren't exactly a priority in EMD and GE, were they? Rough riding however isn't a general feature of two axles trucks - here are generally three axle trucks considered as rough riding. I suspect again that smooth riding three axle trucks weren't a priority here.


Two questions:
1) assuming the same weight on powered axles, how can have a six axle one better starting tractive effort?
2) what acceleration benefits have conventional 4-axle units? Different transmission ratio between motors and axle?

1) Much different weights, atleast 130,000 lbs difference is more tractive load per driving axle. That equates to more tractive effort.

2) They do not have a transmission. When the same amount of amps ( DC traction ) is spread over only 4 powered axles vs. 6 powered axles, the power is more concentrated to the 4 motors and the unit will accelerate more quickly. There is a downside to this, 4 axle units have a smaller short time rating than an equivilent 6 axle.
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Old 03-29-2009, 04:20 AM   #30
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Just another FYI from the article:

The units have the same 87/16 gear ratio as standard GE A.C. units.

Whatever that means...
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Old 03-29-2009, 09:17 AM   #31
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Since the locomotive is weighted down on 6 axles with only 4 axles powered, it is capable of a higher starting tractive
Thats "Less" TE same as DC's ES 44 DC at starting a train, After 15 to 20 MPH TE maybe is about the same. Thats why there dragging the test car all over to prove it's doing as they think.
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Old 03-29-2009, 02:01 PM   #32
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Thats "Less" TE same as DC's ES 44 DC at starting a train, After 15 to 20 MPH TE maybe is about the same. Thats why there dragging the test car all over to prove it's doing as they think.

"Less" than a 6 axle but more than a true 4 axle.
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