For reasons never determined the SDP40F suffered from many derailments,
curtailing its maximum speed which resulted in Amtrak looking for an
alternative locomotive design as its primary motive power. However, it
was thought that the heavy rear end of the locomotive due to the weight
of the boiler and water caused an unbalance that resulted in the
derailments. Further hindering the model was that it used a steam generator to heat and power passenger cars. However, new, electrically heated, cooled, and powered passenger cars were entering the market during the period resulting in the steam generator
becoming obsolete. Overall, however, the SDP40F was not meant as a
long term solution to Amtrak's motive power situation (although,
perhaps, its use was much more brief than intended).
As such, with the development of the F40PH in 1976, which
featured head-end-power (or HEP) to power passenger cars EMD, and the
fact that the model was designed after the GP40 using only a B-B truck
setup (resulting in a more stable platform by use of a shorter frame),
allowed Amtrak to sell its fleet of 150 SDP40Fs as the new models
arrived. Because of this the design had a very short operating life on
Amtrak (all were gone by 1985) but a few were sold to the Atchison,
Topeka & Santa Fe, which overhauled them for use in freight service.
EMD SDP40F Production Roster
For more reading about Electro-Motive products Mike Schafer’s Vintage Diesel Locomotives highlights virtually all of the classic builders and models from Alco PAs to early EMD Geeps. If you’re interested in classic EMDs, or diesels in general, this book gives an excellent general history of both. You might want to also consider the book EMD Locomotives from author Brian Solomon. Solomon's book highlights the history of EMD from its earliest beginnings in the 1920s, to its phenomenal successes in the mid-20th century, and finally its decline into second spot behind General Electric in the late 20th century and eventual sale by General Motors in 2005. The book features 176 pages of EMD history and is filled with excellent photography and illustrations. Finally, Mr. Solomon's Electro-Motive E-Units and F-Units: The Illustrated History of North America's Favorite Locomotives provides an in-depth history of the the builder's classic covered wagons.