The E7 locomotives use rather small 26 inch diameter cold-side cooling fans which are belt driven from the engines. The radiator air outlets were quite large, with either longitudinal slotted grilles or heavy wire guards, and the air velocity coming out was not high enough to prevent leaves and snow and lots of dead bugs from getting into the trailing end of the radiator chamber at high speed. The roof mounted spoilers were intended to create turbulence in the air flow over the outlet which helps deflect snow, leaves and bugs, and also makes the fan a bit more effective by lowering the pressure on the outlet side of the radiators slightly. Since a unit might be running cab leading or cab trailing depending on how the consist was made up, deflectors were put both ahead and behind each radiator outlet. Several railroads tried similar deflectors on their E7 locomotives, some seemed a bit higher off the roof and more noticable than the NYC. I have never found any parts reference to these deflectors in Catalog 90 (that covers the E7), so I think they were either railroad built modifications or were built by aftermarket suppliers.
The cooling system arrangement of the E7 was one of the major design weaknesses of the locomotive (for more information read the precautions in an operators manual about running with one engine shut down) and it was a reason for the total redesign of the fan and radiator arrangement in the development of the E8. The belt and chain drives on the E7 also took lots of assembly and alignment time, on the E8 you just bolted down the roof hatch and connected the cables for the cooling fans. Bill8106, if you are in the Northeast, I would like to suggest that you watch for a program called WHAT'S IN THOSE COVERED WAGONS being shown to some railfan groups in the New England area, it compares the design progression and features of the various models of EMD E-units and F-units with the ALCO covered wagons, including the DL-109, FA and PA units.
