ge mu'ed with emd problems

[dash7]

Hi ,i was wondering if any hoggers sometimes experience problems when a GE is leading an EMD unit or EMD. leading a GE unit?,as i know here in Sydney we sometimes have compatability problems when certain EMD and GE locos are mu'ed in consist ie: pulling, pushing ( load up speeds) .thanks dash 7

[GOLDEN-ARM]

You mean OTHER than the EMD doing all the work, either dragging, or shoving, the GE the entire trip?

[dash7]

You mean OTHER than the EMD doing all the work, either dragging, or shoving, the GE the entire trip?

ummm.............thats not exactly what i meant,thanks anyway

[Peter Radanovic]

I see CP run trains assembled from EMD and GE locomotives allot of times, without any problems or overall changes in locomotive patterns. I've even seen two SD40-2s leading an ES44AC; to make it even weirder, one of the SD40-2s had that rare "arrow and circle" at the back!

[Engineer Spike]

They load at differing rates, but I have had consists of SD40s that were not the same. I have not experienced any real problems. The new ES series load fast. They are a welcome change from the AC4400.

[dash7]

Thanks for that Spike i did'nt know that the older dash 9's were'nt quik on loading up, do the newer emd's load up as quik as say a 40-2 or 50 series? cheers, dash7

[Allen Hazen]

Slow loading is one of the complaints I have heard repeatedly about GE locomotives: U-series, Dash-7, and later. Since the AC44 uses the same engine as the C44-9 (the two models differ mainly in that the AC44 has AC traction motors and the Dash-9 has DC), an uprated version of the FDL engine used on U- Dash-7 and Dash-8 GE locomotives, I am not surprised that the same complaints get made about it.

The evolution series, ES44AC and ES44DC, use a new design of diesel engine (12 large cylinders instead of 16 smaller ones, new and more complicated cooling system, maybe some new thinking in other respects as well), and I have seen a couple of engineer comments on these forums to the effect that they load faster than the earlier units.

It is recommended that the throttle be reduced to a lower notch before hitting switches or crossovers (diamonds)-- it's apparently not good for traction motors to be bounced around while under full electrical field strength. Thus locomotives have to be reloaded after every switch or crossing. Which made slow loading a real annoyance: this is remarked on in Vergil Staff's "D-Day on the Western Pacific" (a history of WP dieselization and diesel locomotives) as a major complaint when WP (which had previously been all-EMD as far as road power was concerned) bought U30B units.

[dash7]

Allen, i appreciate it,when i posted this question i had the NR(cv40-9i) MU'ed with the 82 class(Jt42c) in mind and i sort of wanted the US domestic model comparison and you have solved this mystery for me!. ps:i put the emd and goninan/ge model numbers in brackets for other railfans who were wondering what the class numbers meant! thanks again Allen,cheers dash7

[thebigc]

It is recommended that the throttle be reduced to a lower notch before hitting switches or crossovers (diamonds)-- it's apparently not good for traction motors to be bounced around while under full electrical field strength. Thus locomotives have to be reloaded after every switch or crossing. Which made slow loading a real annoyance: this is remarked on in Vergil Staff's "D-Day on the Western Pacific" (a history of WP dieselization and diesel locomotives) as a major complaint when WP (which had previously been all-EMD as far as road power was concerned) bought U30B units.

That restriction varies from RR to RR but only applies to railroad crossings at grade, or diamonds. No restrictions on switches that I'm aware of.

[jg greenwood]

It is recommended that the throttle be reduced to a lower notch before hitting switches or crossovers (diamonds)-- it's apparently not good for traction motors to be bounced around while under full electrical field strength. Thus locomotives have to be reloaded after every switch or crossing. Which made slow loading a real annoyance: this is remarked on in Vergil Staff's "D-Day on the Western Pacific" (a history of WP dieselization and diesel locomotives) as a major complaint when WP (which had previously been all-EMD as far as road power was concerned) bought U30B units.

That restriction varies from RR to RR but only applies to railroad crossings at grade, or diamonds. No restrictions on switches that I'm aware of.

I believe you're correct, BigC. IIRC, this restriction does not apply to AC locomotives.

[DutchRailnut]

Most likely because of traction motor carbon brush bouncing or carbon brush shunts being shaken while going over a diamond resulting in possible ground relay problems. since AC locomotives don't have high current carbon brushes , only low current field brushes they would not be exposed to same problem.

[jg greenwood]

Thanks for the "reason why", Mr. DutchMan.

[Allen Hazen]

Dash-7:
The NR class is basically a light-weight version of the Dash-9, but with fancy control electronics (it can be re-set to three different horsepower ratings: sort of like the Norfolk Southern's C40-9, but more so, I guess!), and I wouldn't even try to guess what that means to how long it takes to load. GE locomotives in general had the reputation of being slow to load, but modifications to the control electronics could make them... less slow or more slow.

82 class has no direct U.S. analogue: the closest would have been an "SD59" (12-710 engine, CC trucks), but that variant was never offered in the U.S. It is also somewhat lighter in weight than a standard U.S. six-axle unit.

(I've taken the liberty of adding more description here in case there are some North American readers who don't know what the model designations of "export" (actually built under license in Australia, with major components imported from N.A.) EMD and GE locomotives mean.)

Part of the weight reduction for the NR class was the decision to use traction motors smaller than the model 752 motors used on domestic GE locomotives with DC motors. Does this have an effect that you have noticed, Dash-7? A domestic (DC motored) GE would be better than a domestic (DC motored) EMD at sustained low-speed lugging: better short-time ratings for the motors. I have heard that this is not so with the Australian variants (sensibly, since the 82 class was bought for coal trains and the NR with interstate merchandise trains more in mind): the GE motor used on the NR class is smaller than the standard EMD motor.

And have you heard any scuttlebut about the Queensland Railway 5000 class? (These, for the non-Australians, are essentially AC44 done up in a carbody more like the NR class: the first GE AC-motored units in Australia, used in the same coal-mining district as the 82 class.)

The rest of you:
Sorry, I just assumed that-- since one can often, as a train passenger, feel a bump going over switches-- the same operating restrictions would apply to them as to diamonds. Once again, I win: by saying something wrong on a forum with well-informed people on it, I have learned!!! Thank you all!

[dash7]

ALLEN, thanks again for the reply,i have spoken to a couple train drivers in Newcastle about the 5000 class(C40aci) and because of their nearly domestic US axle loads they tell me that they just keep pulling and pulling,also one driver told me{quote}:" that they have a smooth ride like the espee's SD9 cadillacs!"{unquote} how he knew this i don't know but who was i to argue? he also told me they loaded quicker than the pacific national NR class(cv40-9i) but at the time he told me i had know idea what he ment! thankfully now i sort of do. thanks dash7

[GN 599]

One thing is for sure when I am stretching my train back out I use the throttle in corespondance with what a couple of trailing SD40's or whatever. They will be back there getting er all stretched out coming out of a sag or whatever while a GE on the point will still be deciding what to do. If you waited for a GE to respond you would lose a lot of speed coming back up the other side of the sag. Old heads say they used to have a lot of loading problems when they mixed Alco's with other power not so much GE's.