• Differences, FP-45 against SDP40F

  • Discussion of Electro-Motive locomotive products and technology, past and present. Official web site can be found here: http://www.emdiesels.com/.
Discussion of Electro-Motive locomotive products and technology, past and present. Official web site can be found here: http://www.emdiesels.com/.

Moderator: GOLDEN-ARM

  by John_Perkowski
 
Does anyone know the differences between these two locomotive models?

Clearly, the SDP-40F had something different from the FP-45, that caused the -40F to derail.
  by eolesen
 
This has been long debated... the theory that I've bought into was the water storage tanks for the steam boilers. In mariner terms, they had issues with slack tanks...

On the SDP40F, the tanks were mounted high, and supposedly didn't have baffles inside. As the water tanks emptied, the momentum of the water sloshing around it possibly introduced sideways forces that could have caused the derailments.

On the FP45, the water storage was below the frame and between the trucks (aft of the fuel tank).
  by Engineer Spike
 
One other difference was that different trucks were used between the two models. The FP45 had Flexicoil trucks, while the SDP40F had HT-C. The Flexicoil had coil springs and one motor faced the opposite direction in the truck from the others. The HT-C used rubber blocks for suspension. Supposedly the SDP40F used a lightweight version which was one speculation as a cause of the derailments. Some say that because of this debacle over trucks is why Contrail ordered all SD40-2 and most SD50 with Flexicoil. I don't buy it because ex EL SD45-2 had HT-C, and it was likely because of the supply of used trucks from traded in units.
  by chrisf
 
Engineer Spike wrote: Thu Nov 03, 2022 8:01 pmSome say that because of this debacle over trucks is why Contrail ordered all SD40-2 and most SD50 with Flexicoil. I don't buy it because ex EL SD45-2 had HT-C, and it was likely because of the supply of used trucks from traded in units.
Sure, but Conrail didn’t order those SD45-2s, EL did, and they were built in 1972, before any SDP40F was built.
Conrail also pretty much only used the SD45-2s as helpers in the Altoona area, so it ‘d seem that they weren’t too comfortable with the idea of running them at high speed. Conrail also wouldn’t have been trading in power that used that version of the Flexicoil truck at the time they were buying SD40-2s and the early SD50s.