Pennsy DD1 Electric, 1911

Warren Avis posted two photos with the comment: "PRR DD-1 with and without clothes . They were used from Manhattan Transfer through the tunnels to NYC as steam was forbidden. There were 66 engines making 33 pairs running on 650 VDC third rail. Not sure if the little pantograph on top was ever used, anyone?"

Elliott Moxley: Little pan was used with overhead third rail at crossovers and double slip switches in NY Penn, where it was sometimes impossible to have third rail on either side. NYC and New Haven units had similar pans for use in GCT.

Philip Donnelly: Those large traction motors connected via jack shaft connected fly wheels utilizing connecting rods to the drive wheels. Coming from a stop in PSNY with heavyweight cars the engines couldn't develop enough momentum to coast through multiple double slips hence the overhead 3rd rail over the double slips and the small pantograph on the roof. Minor historical note the PRR had small pockets put in the ceiling of the north river tunnels for possible overhead 3rd rail if the sump pumps couldn't handle water seepage but it wasn't necessary.

Bruce Gillette: Wonder if they moved smoothly or could you feel a jumping motion with the Jack Shaft hitting full stroke.

Paul Prohaska: Bruce Gillette I was born too late (1948) to ride behind DD1 motors. All but a few were gone to LIRR in the 30's. Our neighbor in Bethesda, Sig Hagara, drove DD1's, then P5a's and finally GG1's. He said the DD1 pairs were very smooth. He operated them between Manhattan Transfer and Penn Station, as steam was barred from the river tunnels. He liked them. He said the P5a was so so. Sig loved the GG1.

Philip Donnelly: One thing that escaped my attention for years is that there are no steam fitting on the DD-1's , the passenger cars would have been heated in the yard and station with stationary lines so perhaps it wasn't necessary the supply heat for the 7 mile trip to Manhattan Transfer and swapping off the electric for steam would be faster without connecting/disconnecting the steam.

1

2
Greg Robinson posted
That awkward moment when you're trying to develop a new technology, but can't quite figure out how to let go of the older one.
Pennsylvania RR, DD1 electric, 1911.
Taylor Rush: I guess they were actually pretty successful locomotives though. Lasted until 1957 and one of them even survives in preservation today.
James Ridgway Jr.: Was actually wire train engine for PRR until the end...Saved by Penn Central, and sent to Strasburg...
Lorenzo Pantani: They needed 10 more years to have smaller engines that may be mounted down between the frame walls.

Greg's post was first, and this is what I wrote when I saw that post:

Pennsy needed electric locomotives to use in their tunnels under Manhattan Island and the rivers on each side. I've seen pictures of this coupled wheel locomotive before, but always with the cab on it. I can understand that the electric motors of that era would be too big to be placed down by the axle like they are now. Perhaps chains were not strong enough to handle the horsepower? Some comments indicate these were built by Baldwin, one of the major steam locomotive manufactures. Those engineers understood reciprocating drives, not chains. There must be gear reduction in the motors because I can't imagine that the motors would run slow enough to be direct coupled to the wheels. The design must have been effective because these stayed in service for decades.