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I understand the SD 70 MACHs are not B1+1B because some of the power from the prime mover that would have been for all six motors in a C+C unit was diverted for HEP. While Alaska Railroad's HEP-equipped units also draw power from the prime mover, that can be switched to allow all 6 axles to be used...

FP45, SDP40/45, SDP40F and F40C models were all C-C. MILW's SDL39s were C-C as well, despite the lightweight truck design. Santa Fe converted one of the 1936 Super Chief B-B boxcabs by adding an idler axle to each truck, resulting in a 1B-1B configuration. From what I remember, the trucks were repl...

While A-1-A has been used around the world by EMD on E units and some exports, those were done with trucks that were designed from the rail up as A-1-A or were created from a C truck by removing the middle motor on the SD Flexicoil, as on the FP-45, or it's littler sibling the GC truck used on the S...

An F9 uses the DC main generator for starting. Electric starter motors came in with the AR10 alternator with the 40 series about 1966.

The interlock devices are separate from the center bearing, chains or hooks or links, if you look at the bogie carefully you should be able to identify those parts as they are all external to the bogie. What you have pictured in yellow are the center bearing wear liners; today they are made of nylon...

Regarding lateral flexibility, the D trucks used standard to EMD Hyatt cylindrical roller bearings where the journal box is laterally captive between the pedestals of the frame and lateral travel of the axle is allowed by the cylindrical rollers with relatively little lateral resistance until a thru...

I should have mentioned that all EMD bogies have interlocks between the bogie and underframe to prevent the bogie from detaching in a derailment. IIRC, on the GC bogie there are interlocks from the underframe to bolster and from the bolster to the bogie frame. On some bogies, the connection is direc...

The part you have pictured is called the bolster and this one is part of the EMD GC bogie. Circled in red is the center bearing bowl; a mating circular part called the center bearing is welded to the bottom of the underframe of the locomotive which allows the bogie to swivel in curves while transfer...

At EMD before the GP model was introduced, the 2-axle swing hanger truck was simply called the "freight truck". I suspect it was the introduction of the SD model that made that designation unclear and led to calling it the GP truck.

Bogieman-- Re: design of the trucks. Given GE's history in the locomotive business, surely some of their own engineers would have known a good deal about truck design? So even if the detailed design was GSI or Commonwealth, it would have been in consultation with GE's engineering people. (I know th...

As always, great information. Any idea which company designed these 3 and 4 axle bogies? I am thinking it was GSI or Commonwealth rather than GE.

Pneudyne, Thanks for posting these arrangement drawings, really helps to understand these locos.

Dave

Trying (unsuccessfully) to get more details on the U50's trucks, I looked at https://utahrails.net/up/up-diesel-story-1934-1982.php (part of a history of UP motive power). Locomotive types are covered, paragraph or so each, in roughly chronological order. In reference to the DD35, it says that 14 o...

Bogieman-- Thank you! I was hoping you might comment on this. (i) ... The GE and EMD eight axle units for Brazil (all the GE and the newer EMD ones having span bolsters and four B trucks) have the couplers mounted on the locomotive frame and not on the span bolster. Do they have the centre plate fo...

I, too, am interested in any details of the B+B span bolster trucks used on these locomotives. I have not found any pictures that just show the trucks or the span bolsters, I'm really curious about the connection from the span bolster to the underframe - I assume it is a typical center plate that ex...