• Older GE vs. older EMD pulling contest

  • Discussion of General Electric locomotive technology. Current official information can be found here: www.getransportation.com.
Discussion of General Electric locomotive technology. Current official information can be found here: www.getransportation.com.

Moderators: AMTK84, MEC407

  by checexcitation
 
I thought Id throw this out for debate!
A competition!

2 B23-7's with FB-2 trucks vs. 2 GP9's with Blombergs

Theoretically, a 1% grade 5 miles long,
Light rain is falling
All units of both makes have good sanders on leading axles
Both contestants have full fuel tanks
Both contestants are running as designed. GE has CMR whelelslip system, GP9's have EMD's wheelslip relay system.
Trainmaster needs to clear the yard of 200 loaded sand cars
Who gets more cars?
Which units make it up the hill easiest (lugging), fastest (HP) and with less slippage (wheelslip detection/ correction)?
Remember that real world may be different than theoretical !

This comparison is founded with some validity as I am aware of some RR's with this motive power mix.

Anyone want to start a debate on this?

I'm hoping for the GE's myself!

  by GOLDEN-ARM
 
How is this a competition? The EMD's are 1000 HP less than the GE's, so you have already thrown the "contest" in favor of those toaster-motors. Why not a GP-35, or at least U-18's, instead of those '23's. If it's a "contest", make it a fair one. :P

  by LongIslandRRTom
 
Yea.. B23-7s are not the same generation as GP9's.. No contest at all there.

A fairer comparison I think would be B23-7's vs. GP39-2's (which are turbocharged and thus a bit more powerful than the normally-aspirated 2000hp GP38-2's).. Around the same generation and comparable power.

People might think I'm wierd or something, but I think I like the looks of the BQ23-7 over the plain B23-7.. :P
Last edited by LongIslandRRTom on Sat Jan 07, 2006 4:21 pm, edited 1 time in total.

  by Alcoman
 
Why you are at it on being "fair"; lets include an Alco C424 too.

  by emd_SD_60
 
How about a C30-7 vs. a SD40-2? At least both have equal horsepower.

  by byte
 
Am I the only one to think that this would never work due to the coupler knuckles breaking? :-)

  by checexcitation
 
Well, the comparison as posted was was just to open a friendly debate.
I know that the "generation gap" of electronics and higher rated horsepower of the GE's would seem to skew things towards the GE's. But, I have a friend at a railroad who tells me that to him, it seems like their GP9's, in pairs, can out-pull their G.E. pairs of B23's. At least under certain conditions. He, however, is a Conductor, not an Engineer.
I was pretty surprised at his comments and I was just trying to provoke a discussion that might include wheelslip systems, truck design, etc.
I guess I should just have asked for thoughts on this straight up, but was thinking that others would weigh in with their own view, through experiance or as observers, using this defined scenario.

This, then, CAN be a valid comparison. (For my friends RR at least!)

  by MEC407
 
It's entirely possible that the GP9s are able to get up to speed faster than the B23s, despite the substantial horsepower difference. But I would bet that the B23s could haul more cars, and up a steeper grade, than the GP9s could.

Somewhat related, and this is only anecdotal and unscientific, but I think it's worth mentioning: I was told by a person who used to work for the Maine Central that their U18Bs pulled just as well as (if not slightly-better-than) their GP38s, particularly on the strenuous Mountain Division. I'm not sure why, and I wasn't there in person so I certainly can't back it up, but I thought it was interesting, and other MEC folks have told me the same thing.

MEC's U18Bs had Blomberg trucks, which means they wouldn't have had any of the alleged advantages of the FB2 truck.

  by EDM5970
 
I heard a story, right from the horses mouth, about the first time Green Mountain used one of the GP-9s, many years ago. They put it on a ballast train, along with an RS-1, just in case. The Geep got on some wet rail, and couldn't move the train, while the RS-1 could. The horsepower difference means nothing at that speed; weight on drivers does, so the units were pretty equal there. Right?

However, consider the fact that in the first notch, a 1750 HP Geep will put more HP to the rail than a 1000 HP Alco will. This would tend to make the Geep slip easier. One of the interesting things about the "horsepower race" was the fact that the more HP a unit had, the better the wheel slip system had to be. Horsepower was fairly easy, but controlling it was another story.

Going back to the original question, I would tend to say the GEs would be the winners in all respects. They have an HP advantage, so once the entire train is moving they would be able to accelerate and make better time over the road. The GE 752 TMs are larger than the EMD motors, so lugging ability would be no issue. The CMR wheelslip system is a generation or two (or more!) newer than what a typical GP-9 has, so there is no comparison there. The FB trucks on the GEs were designed with zero weight transfer in mind, so even the GE trucks offer an advantage over the Blombergs.

As Alcoman and Golden Arm have suggested, this isn't even a fair fight. Better comparisons might be U-18Bs, RS-11s and GP-9s; GP-38s and C-420s; GP-30s, B/U-23s and C-424s; U-25s, C-425s and GP-35s. Keep the weights and horsepowers equal, and in roughtly the same era of wheelslip development, which isn't really possible as far as the WS goes.

(As a side note, with a screen name like Checexcitation, I would imagine there is a bias toward GE. Myself, I prefer static or type E, with a 17MG8 governor.)

  by checexcitation
 
EDM5970,
Well, this is more of what I was looking for I guess. Your response seems logical in that newer, higher HP, bigger motors etc. etc. GE's should out-do the older GP9/10 type locos. I was just wondering if real world experiance might suggest otherwise, based on my conversations with a conductor I know.
As you suggest, the application of power to the rail is probably the real deterniner here. Maybe the Geeps dig in better due to their slower loading load regulators before slipping? Perhaps the smoother riding Blombergs stay 'planted" to the rail better?
Anyway, While I do have a fondness for many of the GE locomotives, despite the screen name, I actually prefer Alcos to anything else. I just don't know a whole lot about their traction control systems!
Does anyone have a good explanation as to the supposed advantages of an FB-2 truck?
Are the "rubber pads "in place of springs supposed to provide a better ride? Or, have to do with adhesion, or both?

Thanks to all

  by MEC407
 
checexcitation wrote:Does anyone have a good explanation as to the supposed advantages of an FB-2 truck? Are the "rubber pads "in place of springs supposed to provide a better ride? Or, have to do with adhesion, or both?
Somewhere on the web -- can't remember if it's here or on his personal web site -- Michael Eby (a.k.a. trainiax) gave an explanation of MLW's "ZWT" truck. Apparently this truck and the GE FB2 have a lot in common.

  by GOLDEN-ARM
 
As for the second part of the question, in the "real" world, those units, on that grade, should realistically pull between 1600 pounds and one ton, per horsepower. Adequate adhesion depends a lot on efficient sanding, and in the case of those EMD's, a masters touch, on that throttle. With those early geeps, less is definately worth more, as far as throttle position versus rail/wheel adhesion. Too many guys think higher notches means getting up the hill, when often times, it only means excessive slippage, and ultimately, stalling. Those "toaster" motors can basically be left wide open, and the slippage can be regulated through manipulation of the independant brake, and sanding. I wouldn't put more than 45 cars on the GE's, and between 35 and 40 on the Geeps, with that grade. Just my own experiences, however. Regards :wink:

  by trainiac
 
checexcitation wrote:
Does anyone have a good explanation as to the supposed advantages of an FB-2 truck? Are the "rubber pads "in place of springs supposed to provide a better ride? Or, have to do with adhesion, or both?

Somewhere on the web -- can't remember if it's here or on his personal web site -- Michael Eby (a.k.a. trainiax) gave an explanation of MLW's "ZWT" truck. Apparently this truck and the GE FB2 have a lot in common.
I don't think the MLW truck and FB-2 truck share any parts--they have different castings and a different wheelbase--but they're still very similar in concept and I think GE was inspired by the MLW design. The height at which the rubber pads rest on the truck frame is the same as the height of the springs over the bearings--which means there is (theoretically) no weight transfer from one axle to the other under high-power conditions.

On a Blomberg truck, with the leaf spring resting on swing hangers below the level of the axles, there would be some weight transfer to the front axle under high-power conditions. This would probably be small, but if it did happen, the rear axle would begin to slip before the front one. Weight transfer can be seen on a cheap HO model with traction tires--try stalling it and the weight transfers to the rear axle to the point where the front axle lifts off the track. That's because these trucks are fastened to the frame well above the axle line.

The rubber pads were added for adhesion purposes and, as far as I know, had nothing to do with ride quality. In fact, I've heard from various sources that Blomberg M trucks with rubber pads were actually worse-riding than leaf-spring-equipped Blomberg's, and I've also heard that the GE FB-2 (also with rubber pads) was a very rough rider. By contrast, I've heard good things regarding the ride of spring-equipped trucks such as the standard Blomberg, 3-axle Flexicoil and HTC. Later Blomberg trucks switched back to the leaf spring, and I'm guessing (this is pure speculation) that it was because the adhesion benefits did not outweigh the loss in ride quality.

  by Tadman
 
A few years back, I took SW Chief Chi-Lawrence, KS. I had two deadhead BNSF employees, and I asked them a similar question: given egual locomotives, what would you prefer? The answer was GE's aren't screwed together as well, IE control stands rattle too much. In terms of power, the difference is negligable on an intermodal, but on a coal drag, they'd want nothing other than an SD70MAC. They were pretty firm on that judgement too, saying nothing will pull like a big MAC on a coaler.

  by MEC407
 
Unfortunately, recent reports seem to indicate that the SD70ACe does not perform as well as the SD70MAC did. On the other hand, folks are also saying that the ES44AC performs better than the AC4400.
Last edited by MEC407 on Sat Feb 04, 2006 12:56 pm, edited 1 time in total.