MidlandMikeCould it be that the P motors were designed for Cleveland Terminal service, and later went to NY terminal service, whereas the GG-1 was designed for mainline service?
I seem to remember they were designed for reasonably high top speed in Cleveland service, where the catenary wouldn't restrict speed as third rail does. And they were explicitly rebuilt at GE for 70mph speed.
Now, NYC is a little infamous for having operated electric power at wildly greater than posted speed -- ask Mr. Wilgus how those four-wheel trucks got shoehorned into the S-motors -- but I doubt the speeds in the PC era were greater than 70mph on the fastest part of the line to Harmon; I certainly don't remember them being (although the curve superelevation in the waning years of the P-motor 'experience' could be high enough to produce actual discomfort when stopped on it, I think something like 10.5 degrees in some places)
Dick Dawson ... I noted that the front trucks of the P-2s often slapped back and forth between the rails. ... I did observe that the GG1 seemed to ride more stably laterally than the P-2. ...
... I noted that the front trucks of the P-2s often slapped back and forth between the rails. ... I did observe that the GG1 seemed to ride more stably laterally than the P-2. ...
Dick DawsonWhile waiting for my MU train into GCT, I would sometimes see through trains blasting through on the inner tracks. I noted that the front trucks of the P-2s often slapped back and forth between the rails. Rightly or wrongly, I attributed this to insufficient maintenance of the running gear.
I would agree with this, a further question being whether the observed truck motion were strictly lateral or had an oscillating component around the pivot (e.g. potential hunting). Someone with access to the drawings might look at the bolster lateral-accommodation methods and post something here; since this was a common occurrence, I'm hesitant to attribute only 'accidental' things like wear of wedges or broken springs as the cause.
I'd add that stiffer lateral on the lead trucks should be 'designed in', as the rigid wheelbase of the actual chassis half will likely have the same 'self-steering' action as a comparable steam-locomotive rigid wheelbase and the requirements for effective lead-truck guiding should be comparable.
I had the opportunity to ride in the cab of a P-2 from GCT to Harmon and later in a (by then) Penn Central GG1 from Penn Station to North Philadelphia. I did observe that the GG1 seemed to ride more stably laterally than the P-2.
A large part of this is likely the quill drive arrangement, which has a much smaller lateral unsprung mass (and at least the opportunity for much better lateral compliance control, if the spring arrangements in the quill drive are properly lubricated). P2s carry the weight of the drive much lower down, and the lateral is likely more highly constrained by the mounts for the nose-suspended motors.
It was surprising to me, however, how much more cramped the GG1's cab was than the P-2's.
Drafty, too, and hung so far out you almost have to guess the track you're going onto at crossovers.
As far as power is concerned, the NYC diagram for the P-2 gave continuous ratings of 4243 hp at 39 mph (40,800 lbs. tractive effort) and 4262 hp at 55.5 mph (28,800 lbs. tractive effort).
This adds useful information to the discussion. Thanks!
When I worked on the NYC in 1967 and 1968, I commuted from the Greystone station in northwestern Yonkers. While waiting for my MU train into GCT, I would sometimes see through trains blasting through on the inner tracks. I noted that the front trucks of the P-2s often slapped back and forth between the rails. Rightly or wrongly, I attributed this to insufficient maintenance of the running gear. I had the opportunity to ride in the cab of a P-2 from GCT to Harmon and later in a (by then) Penn Central GG1 from Penn Station to North Philadelphia. I did observe that the GG1 seemed to ride more stably laterally than the P-2. It was surprising to me, however, how much more cramped the GG1's cab was than the P-2's. As far as power is concerned, the NYC diagram for the P-2 gave continuous ratings of 4243 hp at 39 mph (40,800 lbs. tractive effort) and 4262 hp at 55.5 mph (28,800 lbs. tractive effort).
Since hourly rating was barely over 3,000hp, the 5,200hp would be a short term rating (5 minutes or less). I would also guess that was with a shunted field.
Erik_MagThe book also states that the P's were good for 50,500 lb T.E at 35mph and 2.7kV, working out to 4,700 drawbar hp. This suggests they should be good for 5,200 drawbar hp with 3kV at 38.9 mph.
But wouldn't this be motor-limited with the 278Cs?
For fun, go back and find the comparable numbers for the as-converted Ps on third rail, with the 755As (which apparently were much higher in power, perhaps due to lower insulation requirements, than the motors they replaced).
I do not remember when the third-rail voltage was increased, but if that were done in the era the Ps were running it would likely not compromise the insulation significantly but would produce a nifty boost in the achievable power...
Overmod Someone here will have the actual instantaneous and hourly rating for these. In Cleveland (with the original 3kV setup) they had just over 3000 continuous horsepower; after the 660V rebuild this increased to over 4200, but this was still shy of a GG1. I do not know how arrangements for back EMF were handled and have never seen a speed-to-TE graph for those locomotives.
Someone here will have the actual instantaneous and hourly rating for these. In Cleveland (with the original 3kV setup) they had just over 3000 continuous horsepower; after the 660V rebuild this increased to over 4200, but this was still shy of a GG1. I do not know how arrangements for back EMF were handled and have never seen a speed-to-TE graph for those locomotives.
Jack Grasso's book on the CUT states that the continuous rating at 3kV was 2,635hp, 1 hour rating at 3kV was 3,030hp. The book also states that the P's were good for 50,500 lb T.E at 35mph and 2.7kV, working out to 4,700 drawbar hp. This suggests they should be good for 5,200 drawbar hp with 3kV at 38.9 mph.
The P motor was the first of the 2-C+C-2 wheel arrangements. Soon after, NH bought motors in that arrangement. PRR leased an EP-3 from NH to test it agains some other motors, eventually adopting the wheel arrangement for the GG-1.
I loved the hell out of P-motors as a kid. They were by far the best motors on the still-exotic NYC line to Harmon. Especially splendid in lightning stripe (and I still don't quite understand why the last of those was scrapped without being offered for preservation...)
Article in Trains back lo! these many years ago that said about the porch on an SD-40 that you had 'room to set up a card table and deal'. Of course our high-school railroad club has the photographic proof somewhere that that comment is not hyperbole on a P-motor. (As long as you don't care about stuff impeding legroom under the table after you set it up!)
The GG1 was explicitly streamlined, and intended for much faster service than the P (either in Cleveland or Harmon service). There was, at least initially, more care to provide high-speed compliance in the suspension, and roller bearings on all axles (I don't think the P-motors had roller bearings even after the rebuild in the Fifties). Top speed, and I think it was a hard limit, was 70mph (GG1s could run far faster).
Naturally the motors were different, and I believe so were the drives (the GG1 twin 'universal' motors were capable of operating on DC, but of course PRR did not operate them that way). GG1 had fairly good quill drive; I think the P-motors were nose-suspended (original motor 278C, rebuilt motor 755A for those who want to look up motor data).
I do not have a hard reference whether the rather-substantial weight reduction during the 'rebuilding' was done because the removed 3000V equipment was 'that much' heavier or because there were restrictions on the Park Avenue viaduct that had to be met. Someone out there will know.
I've always admired the NYC's P motor class of electric locomotives. Although the GG-1 is probably considered by most people to be handsomer than the P motor, I think the P's just exuded a strength and masculinity (for lack of a better term) that compared very favorably with any others.
But what about power? Pulling ability? Efficiency?
Would anyone here care to enlighten me a bit by comparing and contrasting these two fine engines?
Thanks.
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