UP FEFs

I know UP's FEF-1s have smaller driving wheels and various other differences from the later 4-8-4s. But what's the difference between UP's FEF-2 and FEF-3 engines? In looking at photos, I can't find any.

Pilots - the FEF-2 has a GSC drop-coupler pilot, while the FEF-3 has a GSC swing-coupler pilot (same as used on the 3985 and BigBoys).

Stuart

Thanks! I thought the pilots looked a little different but didn't know that was the distinction between the two classes. I'm in the process of drawing an FEF-3.

Not sure anyone's still interested in this topic, but for what it's worth there were a few differences in the 820-34 and 835-44 series (known in the UP's "mechanical department" at Headquarters as "FEF-2" and "FEF-3").

A number of them are very minor and I won't attempt to treat them here. And, some depend upon the date you're looking at.

First, and as you likley know, FEF-2 was delivered with a single stack and later changed to a twin stack. FEF-3 was delivered with a different "front end" arrangment in the smokebox and was built with double stacks. Those on FEF-2 were smaller than the third series, and they remained so through their careers. Too, the third series had a heavy sheetmetal "casing" surrounding the stacks while FEF-2 was fitted with something approximating a "spacer" between the stacks to smooth the appearance.

As constructed, the side rods were somewhat different also, the design of the grease cup arrangement at the crank pins changing between the period the two classes were built. By the time FEF-3 was constructed Union Pacific had embarked upon a program of moving rod grease cups to a vertical position ahead of the crank pins, replacing former designs. Many engines of different classes retained earlier rod types right up to the end of steam operations, but I do believe all FEF-2's had their rods replaced with the type fitted new to FEF-3, and the drawings for these rods reflect the addition of class FEF-2 for "all replacments."

You may also know that some of the FEF-2 locos were fitted new with Sunbeam headlights. I've forgotten just which one. This sort of thing was common on UP. These appear in a sort of "can" shape as compared with the Pyle-National types.

As new, FEF-2 was also equipped with the early design of Hancock "Long Bell" chime whistle (of the famous "steamboat" tone). These were "built-up" whistles with flat tops. A close look at early engines will reveal the difference as compared with FEF-3. Many, but not all of the FEF-1 and 2 engines received the later "step-top" cast bell Hancock whistles. On the step-top type you can see the length of each chime in the whistle bell, denoting the various designed pitches. Shorter lengths produce higher tones, and conversely longer lengths are lower in tone.

Interestingly, FEF-3 received the "smoke lifters" well before the two earlier classes as well. While I don't know this with certainty, I believe it to be the result of the front end appliance arrangement in the smokebox coupled with the much larger stack diameters. Actually, the smoke lifter (or "wind wing", "elephant ear" or "smoke wing") program began when FEF-3 was still arranged to burn coal.

Another less visible difference was the fitting of cab enclosure doors to FEF-3 as new, but some of the two earlier classes also received these later.

That's about all I can think of right now. Of course, much of this requires detail viewing and doesn't help much in action shots or when engines are found in close perspective to other locos.

Hope this helps a bit.

John

The bid difference in boilers was the FEF-2 had type E superheater units with smaller tubes, while the war-time UP engines reverted to type A units with few, but bigger superheater tubes.

The FEF-3 had the Nathan 4000 type injector under cab on right side, while the FEF-2 had a simpler model w/ the starting valve mounted under that cab.

FEF-3 had a cast bracket for the generator mounted low behind the 4th driver, later removed & gen'r mounted up on boiler.

FEF-3 had a different boiler check valve

***Speculation***
Improvements in front-end boiler design were supposed to improve efficiency by reducing back pressure: less energy goes up the stack. U.P. put a lot of effort into this; the double stacks of their last steam locomotives were part of a package meant to minimize back pressure.
Part of the effect was surely that exhaust went up the stack more slowly than on less efficient locomotives with more of a steam blast and smaller smodestack cross-sectional area. Intuitively I would think (but intuition is NOT a substitute for knowledge!) that this would ake more of a smoke problem: smoke on an older locomotive was blasted free, but on the U.P.'s final designs might have been trapped in the boundary layer around the big boilers to get into the engineer's eyes.
So: maybe it is not a coincidence that the FEF-3, with the most efficient stacks, got the smoke lifters ("elephant ears") first?
***Pure speculation***

I think that the drifting smoke became an issue with the FEF-3, both at high speed which kept the exhaust from lifting high and at lower speeds where it would wrap around the locomotive. Going by photos, I am sure that all 10 were equipped by mid-summer 1945, which is prior to the oil-buring conversion in the fall of 1945. The first one was slightly different and I think fully riveted, but when applied, all 10 were smoother and riveted only at the lower front part. Photos of coal-burning FEF-3's are not real common, probably due to lack of photographers & expensive film in WWII. The FEF-2 & 1's probably had them applied after conversion to oil as they were shopped, but some engines were in 2T-Gray w/o them until 1950. I have not seen a photo of an FEF-1 or 2 as a coal burner w/ lifters. The FEF-1 smoke lifters are slightly shorter. A detail note is that on the right side lifter there is a small hole in the side about 2/3 up from the running board. This is for the removal of the front-end throttle shaft. I have never seen any official data from AFE files about the smoke lifters, and Kratville's book is sketchy, although in his Challenger book his info on oil burners & smoke lifters is fairly thorough.