In the recent issue of Model Railroader, Jim Hediger answers a reader’s question about the extra length on the FP7. He replied that it was for the steam generator. I think a better answer would be that the extra length is for additional water tank capacity as some standard F units did have steam generators without the extra length. I hate to nit pick, but am I correct?
And incidentally, Jim, if you are reading this, West Unity depicted in your “Working on the Railroad” video series is in Ohio, not Michigan. That must have just been a typo.
However, keep up the good work Jim, as I really think you do a great job at Model Railroader and are quite a modeler and historian. And evidently you are quite an administrator to handle the assignment you have.
I believe that’s correct, an F7A could have a steam generator but only a small water tank. IIRC an FP7 without dynamic brakes could hold about two-and-a-half times more water than a normal F7 A unit.
Yes, you and STIX are correct. MANY F7’s had steam generators, and the extra length of the FP was for a larger water tank. Many passenger F units had systems that allowed water to be moved from steam generator equiped B units into the A unit or vice-versa
The ATSF who prefered F’s for passenger service, only put steam generators in the B units and used the extra space in the A units for larger extra water tanks.
The Northern Pacific put water starage in baggage cars and pumped it to the locos.
EMD F units were available with a number of different options in these regards, all based on the needs of the individual railroad.
The FP allowed for a larger tank and dynamic brakes or an even larger tank without dynamic brakes.
Some passenger F’s also had larger tanks in the unused dynamic brake space and some FP’s had additional water tanks under the frame in front in addition to the larger interior tank.
The combinations are almost as varied as the number of roads that owned them.