Santa Fe F-3 to F-7 upgrades

[Anonymous]

As a lifelong fan of Santa Fe's F-units (I'm sure there are lots of others out there too) - I have read much about Santa Fe gradually upgrading their F-3's of various phases up to F-7 specifications (externally and internally). Does anyone know about any books or magazines that discuss the exact nature of upgrades performed, as well as the timing?

I assume the upgrades were performed in the early 50's, and would include upgrading the traction motors from D-17's to D-27's, the prime movers from 567B's to 567 BC's, heavier traction motor cables, removing all chicken wire from the sides in place of horizontal and/or vertical grilles/louvers.

Any F-unit experts out there who can help out? Thanks!

[Anonymous]

There was a book of F units. I look for it and get back with you

[Anonymous]

Internal changes came first, and not all at once. One of the first changes was conversion to automatic transition. All F3's were originally manual transition units. The big visible external change was the substitution for Farr stainless steel grilles for chicken wire over the ventilation and radiator panel. Some individual units received F7 dynamic brake 36" fans in place of the squirrel cage fans under the screened slots. Santa Fe began applying AirChime M524R air horns in 1950, though this took years to finish, and the Nathans were almost completely replaced by Leslie S-5 air horns, beginning in the late 1950's. Nose and windshield grabirons were not used until required by law, around 1960. Most incandessant bulb Mars oscillating signal lights were replaced with twin sealed beam Mars lights by 1955, and, beginning in 1959, were replaced slowly by shop-built signal lights.

[Anonymous]

Thanks! I'm assuming that the original D-17 traction motors applied to the first passenger F-3's were later substituted with D-27's as on the later F-3's and F-7's (it seems that units 16-21 and 22-30, the Phase I and Phase III units, respectively, had D-17's, whereas the Phase IV F-3's (31-36) were what some have called F-5's (the only difference I'm aware of between F-5's and other Phase IV F-3's are that the F-5's had D-27 traction motors, vs. D-17's for the Phase IV's). I'm assuming Santa Fe did this, with its 3.5% grades on Raton, and the fact that the F-7's, despite having the same horsepower as F-3's, nevertheless had a 30% higher tonnage rating, due to their improved traction motiors.

Any thoughts?