Michael:
The diesel maintenance facilities in Chicago
("Zephyr Pit") and at the Aurora shops were the home bases for all E units
on the east end of the system. So all E units that traversed west to Denver,
Lincoln, Kansas City and the Twin Cities on long distance consists
eventually returned to Chicago. The E units were rotated between long
distance service and the commuter run between Chicago and Aurora to equalize
wear conditions particularly for the diesel engines since the repeated
starting and stopping of commuter service was actually harder on engine,
braking and wheel components than running at sustained speeds over longer
distances. A schedule of this E unit rotation was adhered to for all units
with records kept and submitted for the required "Federal" inspection
reports filed with the FRA, Federal Railway Administration.
[Unable to display image]So the likelihood of
insufficient E units for commuter service would never be an issue.
Probably the only times a geep or other freight
unit was seen on the commuter line was delivering new wheels, passenger
trucks or locomotive traction motors to the Aurora and Chicago maintenance
shops on flat cars that were normal maintenance replacement items required
to be installed in the E units and/or passenger cars.
Hope this is of some value to you.