Baltimore & Ohio E-7 #1416, Pullman Junction, Chicago, Illinois, April 20, 1965, photo by Chuck Zeiler
I started out to explain the screened vent behind the cab door, which appears on all (original) E-7 A-units. I thought it was the intake for the air compressor, so I got out my copy of the EMD Operating Manual Number 2300 for E-7's. The only reference in the manual calls it an "Air Filter Door". Well, Duh! Interestingly, it does not appear on the drawings for the E-7 B-unit, but I feel sure the B-units had air compressors. The Operating Manual states that there was an air compressor driven by each power plant, so that would mean that there were two air compressors. That would indicate to me that there would be no need for a separate intake for each air compressor, so I'm still researching the purpose for the vertical grill behind the cab door, present only on the E-7 A-units. Section 6 of the Operating Manual is devoted to the operation of the steam generators. The January 1979 issue of Trains Magazine has a few articles about the E-7, and in a story by J. W. Hawthorne, it is noted that the first two E-7's delivered to the PRR (5900-5901) were run light from Chicago to Harrisburg because there were no diesel fuel facilities yet built and the locomotives had to make the trip on the fuel they had in Chicago. Apparently, the PRR had bought them with the intention of using them on a Florida run out of Chicago, but arrangements for this train fell apart at the last minute. With no fueling stations between Chicago and Harrisburg, there was no margin for such frivolity as pulling a train, much less heating it. The steam generators, on a cold day, could consume more fuel than the diesels.
According to the June 1986 issue of Mainline Modeler Magazine (see also the May 1986 issue), there were four variations of the vent behind the cab door: the first is as pictured here, a screened opening of similar construction as the radiator intakes, which are not seen because they are covered by the Farr-Air grills. The second variation was fixed slat louvers. The third was variable slat, louvers that could open and close, and the fourth was two individual carbody type filter openings covered with a finer screening material similar to the first design. Also, I have photos of CB&Q E-7's running in winter weather with sheet metal over this vent, so this may be just a carbody air intake. Some photos of these (and other) variations can be seen at these links:
http://www.railpictures.net/viewphoto.php?id=203413&nseq=0
http://www.railpictures.net/viewphoto.php?id=195357&nseq=2
http://www.railpictures.net/viewphoto.php?id=192041&nseq=7
http://www.railpictures.net/viewphoto.php?id=144869&nseq=47
It would appear that the B&O leased some Milwaukee Road coaches for a special, or perhaps a section of a regular train that needed extra equipment, I don't know. My best read of the available information is; this E-7 was delivered to the B&O as class PE-3 #64B on EMD order E472 (c/n 1674), later the class was DP-4. It has been re-equipped with Farr Air grills, which were superior in keeping the rain and snow out of the engine, so it looks much like an E-8 without portholes. The first car behind the power is a six-axle heavyweight sleeper, likely a dormitory car for the porters. I recall on the Burlington (I grew up near the CB&Q) that older sleepers would be pressed into dorm service on specials and extra sections. More info as I come up with it. See the link below for more B&O E-7's.
http://www.northeast.railfan.net/bo.html
