GG-1 vs AEM-7

I don't know enough about GG1-specific motors, but in my prior life in the electric crane industry, I learned enough about that stuff (IE old motors) to realize if the motor moves too fast, the rotor could disintegrate due to high polar weight. Further, traditional american wound rotor motors are tall diameter-wise, and european motors are long, width wise. This means to attain higher rotating speed, the outboard parts of the rotor on american motors would move much faster, creating more potential to disintegrate at overspeed. I have no idea what it would take to 'splode the slip rings or booger up the brushes - that would make a fine mess, though.

So does this mean G's hit 120? Who knows, Noel might. If we compare motors on similar vintage MU's, I was told my a South Shore old-timer (long retired) that he officially unofficially was clocked by some buddies at 132 in the orange MU's, built between 1926 and 1931 - similar vintage to the G. However, I would assume these motors were smaller than a G's motors and could rotate faster.

Hi Tadman,

Obviously we will never know the exact top speed that these GG-1's hit. Did the Towerman use the stopwatch correctly ? How about the fellow that did NOT get caught ? Point is, they somewhat routinely "opened her up" and kept the tight schedule. Safe to say they easily exceeded 100+ mph, and probably "pushed" GG-1 to her limits with the gearing she had.

So, what we need to do, is pass the hat, collect enough money to restore # 4877 or one of her surviving sisters to operating condition. Adjust the gearing to allow some large number, and try her out. And that would be another thread. How to restore a GG-1 to operating condition with a blank check at your disposal.

Another point: the gold cat's whiskers were also very useful for seeing the engine at a distance. Made the engine very visible as she approached you.

pennsy wrote:Hi Tadman,Another point: the gold cat's whiskers were also very useful for seeing the engine at a distance. Made the engine very visible as she approached you.

You could see the whiskers even when the headlight blinded you?

Hi Steemtrayn,

If you are close enough to get blinded by the GG-1's headlights I would suggest that you get off those tracks.

pennsy wrote:Hi Tadman,

Obviously we will never know the exact top speed that these GG-1's hit. Did the Towerman use the stopwatch correctly ? How about the fellow that did NOT get caught ? Point is, they somewhat routinely "opened her up" and kept the tight schedule. Safe to say they easily exceeded 100+ mph, and probably "pushed" GG-1 to her limits with the gearing she had.

So, what we need to do, is pass the hat, collect enough money to restore # 4877 or one of her surviving sisters to operating condition. Adjust the gearing to allow some large number, and try her out. And that would be another thread. How to restore a GG-1 to operating condition with a blank check at your disposal.

Another point: the gold cat's whiskers were also very useful for seeing the engine at a distance. Made the engine very visible as she approached you.

I don't think towermen used stop watches on GG-1's or any other trains,
such activity was way beyond the scope of their duties. Maybe an
official in a tower might do something like that but with a stopwatch, I
doubt it.
As for passing the hat to restore a GG-1 to operation, forget it, you are
dreaming in fantasy land.
Noel Weaver

Noel Weaver wrote:I don't think towermen used stop watches on GG-1's or any other trains,such activity was way beyond the scope of their duties. Maybe an official in a tower might do something like that but with a stopwatch, I doubt it.

I believe this was (and still is, in many cases) the duty of block operators.

The continuous ratings of the GG1 (4620 HP) and the R1 (5000 HP) types mentioned earlier are at 100 MPH. As noted before, these locomotives achieved 115 MPH during the second round of Claymont tests on the PRR in 1934. Kirkland notes in his book on Baldwin diesels that the maximum safe speed of the GG1 and R1 was considered as 100 MPH but that the absolute maximum speed was 120 MPH.

I have now twice quoted John Kirkland's book on Baldwin diesels during a discussion about the GG1; for those unfamiliar with the book, a large amount of information about the Claymont testing is included as support for the design of articulated frame used beneath BLW prototype 6000, which was later recycled as the underframe for the first "Centipede," SAL 4500. Baldwin was well acquainted with the testing data since both the prototype GG1 and the R1 were built at Eddystone by Baldwin; they were then shipped to GE / Erie and Westinghouse / Philadelphia, respectively, for the installation of electrical equipment.

-Will Davis

1. “Complete Analysis of Motor temperature Rise” by F.Felix (GE) & H.G.Jungk (WEMCO) published in AIEE Transactions, 1941 pg 579 is an account of the GG-1 analysis and rating graphs developed in 1935 for the PRR. The feasible tractive efforts and speeds on the graphs keep rising until the transformer’s 1408 volt maximum tap can’t keep pushing current into the motors. Two of the points at the extreme of the graph are:

-assuming the old customary electric/diesel electric 25% adhesion rating, 300,000# on drivers allows 75,000# tractive effort. On the GG-1 this takes about 2760 amps in each of the 3 series motor strings and the transformer voltage can keep this up until 47 mph. That calculates to 9400 horsepower at the rail. Electrically the currents and voltage come to 11,658 kva or 15,628 hp but that just shows that much of the current is low power factor rather than actual horsepower.

-if the actual adhesion available reaches 26.67% then you can operate to the end of the graphs at 80,000# tractive effort. This takes 2900 amps and can be sustained up to 45 mph where it equals 9600 rail horsepower.

I extrapolate on the graph that if you got favorable 28.3% adhesion then you could touch 10,000 horsepower at 44.1 mph but it would be iffy as the voltage will be running out and the overloads will be picking up. One test run you might make it, the next you won’t. Also your train drag has to be 85,000#, no more no less.

If the motors start “cold” they can carry these loads for around 5 minutes before they will overheat. The only affect starting from winter air temperatures would have on this short time rating would be to allow another minute’s work before hitting the maximum 160 C armature or 170 C field temperature limits of 1930’s class B insulation. The 4800 kva transformer’s short term abilities are similar.

One of the sample calculations shows a 16 car train getting to Harrisburg in 80 minutes at up to 90 mph. With all the grades and speed recoveries the armatures run at 120-125 C rise for most of the trip.

2. “The Pennsylvania Railroad Class GG-1 Electric Locomotive” by J.W.Horine (PRR) & H.S. Ogden (GE) published in AIEE Transactions, 1960, pg 107 is about the mounting of a commemorative plaque on the 4800 before it set out from 30th Street for the NHRS May 17, 1959 trip to New York honoring the 25th anniversary of the loco’s first revenue trip from New York to Wilmington on May 16, 1934. In recounting the history the writers mention that during the Claymont tests 4800 (then 4899) repeatedly hauled the instrument coach to 100 mph in 64.5 seconds which required 9300 horsepower, they must be meaning the peak power at the middle of the run up. Some fun figures for 1959 were the fact that it had run 2.8 million miles, averaged 13 mph on an around the around the clock basis and run up a $1.6 million power bill.

Bill

Tad - ever see the TMs out of a DB BR103? The'yre gigantic - bigger than most American types. Granted, that loco was rated to 10,000 HP.

Most traction motors on pre war equipment spun slowly. After the war, you saw the ride of high rpm motors - the NYC subways used 'em, and the Pioneer III used ones that spun to an impressive 6500rpm - faster than even the motors on the Silverliners, and at 800lbs for a 100hp motor, pretty light.

The high RPMs involved with the PIII lead to a few failures from overspeeding, and the Silverliners and Arrows as a result had overspeed protection on them. The thought of a traction motor locking up at high speeds isn't prettty at all.

I don't know how fast AC ones go (though I suspect they're slower), but they should on paper be less prone to flying apart.

Fabulous, Bill -- you nailed it.

Do you suppose, as I now do, that at some point in the past some other author noted the possibility, with exceptionally good adhesion, that the GG1 could theoretically reach 10,000 HP by similar extrapolation of those graphs, and that this sort of thing rather than any test data are the original source for this high figure occasionally quoted in various places?

I would also just note that, at least in Westinghouse's case (from information in this sales brochure) that the assumption of such good adhesion consistently was not considered sensible, thus the "8000 to 9000" figure given in said brochure as a range and the exact 8500 HP at the rail as the given maximum for the GG1; they went with figures they could guarantee, in other words.

Not that I don't believe your sources or your interpretation; I do, one hundred percent. Excellent post.

-Will Davis

Lirr168 wrote:

Noel Weaver wrote:I don't think towermen used stop watches on GG-1's or any other trains,such activity was way beyond the scope of their duties. Maybe an official in a tower might do something like that but with a stopwatch, I doubt it.

I believe this was (and still is, in many cases) the duty of block operators.

First off there are very few block operators left anywhere except the LIRR
and even on the LIRR their ranks have been reduced. On the New
Haven Railroad this was absolutely not part of their duties and operators
did not have stop watches.
I have a lot of rulebooks in my collection and I am not aware of any of
them that show rules pertaining to block operators that required them to
check or clock speeds of trains or engines.
Noel Weaver

Gentlemen,

Excellent data and extrapolations. Great sources. That should put the issues of the GG-1 to bed.

One further point: anyone care to comment on the lifespan of the GG-1 compared to the lifespan of the AEM-7 ?

And if I had really deep pockets: oil/ coolant for the GG-1 transformer that complies with EPA regulations can be found today. Stress cracks can be welded even if they are numerous. Each and every aspect could be effectively dealt with, and so the GG-1 could, in fact, take to the rails under its own power again. It would, of course, be strictly for excursions, tours, shows etc. Similar to # 4449 Northern. But, wouldn't it be something to be able to ride behind a GG-1 once again ?

For current use the GG-1 would be useless even in excursion power.
The cab no longer complies with regulations, the brake valves are no longer certifiable and unit has no HEP or Speed control.
No railroad would assign two engineers on these things and Fireman are thing of past.
Visibility is nill and two pair of eyes would be required to see past long nose.
Bringing a GG-1 up to operating status would require multi- million $$$ and nobody would be willing to put this thing to work for that price.

One further point: anyone care to comment on the lifespan of the GG-1 compared to the lifespan of the AEM-7?

AEM-7's been through one rebuild thus far. How many did the GG-1s experience?

steemtrayn wrote:

pennsy wrote:Hi Tadman,Another point: the gold cat's whiskers were also very useful for seeing the engine at a distance. Made the engine very visible as she approached you.

You could see the whiskers even when the headlight blinded you?

I don't believe too many people, could claim being blinded, by the 32 volt, 75 watt, screw in bulb, used in the old headlights.................. The faint yellow glow they produced, easily illuminated anything, in a 34 foot area, directly ahead of the nose...........................