Why are the SD90MAC, ac6600, and Gp60 so unpopular?

[Trainman440]

Why are the GP60, SD90MAC, and AC6600 so unpopular?

Many modern railways use gp38-2, or gp40-2 instead of GP60s, why? Aren't Gp60s newer?

Again, why are SD70ACE more popular than SD90MAC in todays railways? Arent SD90MACs more modern?

And why is the AC6600 so under used? I see so many more ac4400, or even c44-9ws more than ac6600s. 

So why are these 3 engines so under used/ unpopular?Just trying to learn more about RR.

Thanks

[gmpullman]

Hi, Charles

I really have not studied the exact numbers for the locomotives you mention but I will stick my neck out here and say that the determining factor is probably...

 

Money.

 

For the same reason, you can drive down the streets in most neighborhoods and not see very many Lexus, Merceedes, BMW or Jaguar XJs in the driveways. Maybe not so much that they're unpopular, more like—out of reach, financially.

There are several locomotive leasing companies, Larrys Truck and Electric comes to mind, that will provide needed horsepower to railroads on a cost-plus basis. Railroad companies are not going to invest huge sums when traffic volumes can turn down quickly and leave a huge surplus of equipment sitting idle.

 

 

Many modern railways use gp38-2, or gp40-2 instead of GP60s, why? Aren't Gp60s newer?

Again, pure economics. These locomotives are designed to be rebuilt time after time. They still do the job.

Just a guess on my part... Ed

[mlehman]

The GP60 came along when the RRs were shifting toward C-C locos. The Rio Grande had 3, IIRC, but the durability of their older B-B power meant there was little need for more with them.

IIRC, the SD90MAC had issues with its 6,000 HP engine initially, then it was a LOT of power in one package that suited only a few of the larger RRs. More here: https://en.wikipedia.org/wiki/EMD_SD90MAC

The GE AC6000 in its variants was the competition to the SD90MAC and had engine problems, too. https://en.wikipedia.org/wiki/GE_AC6000CW

[pajrr]

Newer and more modern doesn't always mean better.

[NorthWest]

I think that the D&RGW GP60s were wreck replacements for GP40-2s and were built to SP specifications. But yes, they did get caught up in the trend towards C-C power that started as early as 1967.

As for the 6000 HP power, we've had numerous threads that you can search for. Reliability issues, lack of a market and changing conditions doomed them. They were the last battle in the horsepower race, which had already started to become supplanted by the emissions race.

[binder001]

The units you asked about were on the cutting edge of raising horsepower.  High horsepower isn';t always as desireable a modelers think.  Often high horsepower comes with a price in rated fuel economy.  As fuel prices rose higher and higher the cutting edge stuff fell out of favor.  In their placewere the "good enough" but MUCH more reliable standard models.  Look at UP, they are traditionally among the first to look at higher horsepower.  UP tried the C6000AC and the SD90MAC-H and both were found wanting.  THey used too much fuel and had lower availability than other models.  Now the SD90MAC-Hs and the C60AC's are history while SD70Ms, SD70ACes, C44ACs and GEVOs rule the Overland Route.  GP60 packs quite a bit of horsepower on just four axles.  For switching or local work most railroads would rather use the GP38-2 (or equivalents).

[ricktrains4824]

The SD90MAC did have reliability issues. Many were delivered as SD90/43MAC's for that reason. These came with the "older" 4300hp motors, with the "option" of upgrading to 6000hp later. Most now are either not used sitting in storage, or the 4300hp version.

GE's AC6000 also had issues, and many are now remotored to the new ES4400 motors. 

The GP60 did offer higher hp than a GP38, but many roads felt that the higher hp was just not needed on a 4 axle unit. (Notable exceptions SF, using them on their "Z" trains.)

Many felt that the high hp with poor fuel economy was just not a great idea, and then fuel prices began to skyrocket, proving their point.

Between poor reliability and poor fuel economy, these units were doomed from day 1.

[BigDaddy]

Larry's Truck and Electric....?  sad video.  We had a similar company in Baltimore, Striegel Supply.  They had a much smaller operation, but I remember several rusting 44 tonners outside.  I intend to use the Vulcan Tool Works (Walther) building to model a similar operation

Admittedly pretty far off topic

[gmpullman]

BigDaddy

Larry's Truck and Electric....?  sad video.

Where locos go to die...

https://www.google.com/search?q=larry%27s+truck+and+electric&biw=1344&bih=770&tbm=isch&tbo=u&source=univ&sa=X&sqi=2&ved=0ahUKEwj09bnihcTMAhWDdx4KHR4LAc0QsAQIIg

BigDaddy

I intend to use the Vulcan Tool Works (Walther) building to model a similar operation

Take a look at the next-to last photo here...

http://trainweb.org/lfnwfan/html/Larry's.htm

Not a bad idea. I had always wanted to make several diesel carcasses in a scrap yard. Walthers has the prime mover kit. It would make a neat scene.

Not all that far off topic...

Ed

 

[dehusman]

SD90's are very unreliable. One railroad parked them because it was cheaper to not run them than to suffer the cost of delays from road failures.

[Trainman440]

Okay! I get it now.

Thanks for the replies

[jmbjmb]

I'm not a professional railroader, so please jump in and correct me, but I was always under the impression there was some optimum ratio between horsepower and axles due to the limits of steel wheels on steel rail.  That at low speed all the extra horsepower was wasted becasue you can only start the train so fast before the wheels slipped and most routes couldn't take advantage of the high speed due to  traffic and other limitations.

Seem to recall seeing something even back in the 80s about that which was why the sd40-2 became such a standard until computer control helped with the wheel slip issue.

Does someone have more data?

 

jim

[BRAKIE]

CR's almost GP60M-Is..

CR ordered 30 SD60Is but,change the order to 26 GP60M-Is along with 4 SD70MACs and 4 GE AC4400CWs these AC units was  for testing. However,after testing EMDs SD80 demonstrators CR decided to cancel the order for the GP60M-Is,SD70MACs and the AC4400CW and ordered 28 SD80MACs.

In this case AC power won over the GP60M-I.

[ericsp]

GP60s are suited to hauling fast trains over level terrain, where that excess horsepower can be put to use running the train fast, but not well suited for much (or anything) else. Their relatively light weight means they probably cannot haul much more tonnage than a GP38-2 or GP40-2 (unless new technology increased the tractive effort per unit weight of locomotive) so in low speed much of the horsepower is not used. Higher horsepower engines usually are not as fuel efficient.

[BRAKIE]

ericsp

GP60s are suited to hauling fast trains over level terrain, where that excess horsepower can be put to use running the train fast, but not well suited for much (or anything) else.

CR had planed on using the GP60Ms on Mail Trains in order to replace some of the GP40-2s but,that GP60M deal was canceled.GP40-2 continued pulling Mail Trains.

C&O and N&W favored 4 axle units until EMD SD35 was produce and even at that C&O maintained a large fleet of 4 axle Geeps from GP7s to GP40-2s until it was merged into CSX in '87..N&W started buying six axle unit with the SD35 and SD45. C&O passed on the SD45 but,was charmed by the SD40.

[dehusman]

jmbjmb

I'm not a professional railroader, so please jump in and correct me, but I was always under the impression there was some optimum ratio between horsepower and axles due to the limits of steel wheels on steel rail. That at low speed all the extra horsepower was wasted becasue you can only start the train so fast before the wheels slipped and most routes couldn't take advantage of the high speed due to traffic and other limitations.

Correct the limit of the power is the wheel slip.  On an "analog" engine the engineer controlled wheel slip.  As locomotives became more sophisticated the wheel slip control followed suit.  The maximum adhesion is right as the locomotive wheel is beginning to slip.

The various models all tried to improve the wheel slip getting it down to speed control of the wheels to less than seconds.  The real breakthrough came with AC traction motors that can respond in millliseconds.  That way the wheels (individual axles with GE and individual trucks with EMD) can remain right at that optimal wheel speed.

Locomotives have a continuous rating that is the lowest speed at which they can maintain power for a set time.  AC engines can pretty much go down to a crawl for as long as needed.  The advantage of AC engines is that they can deliver the power to the rails at lower train speeds.