Nostalgia & History > Why F Units for Passenger Trains

I've wondered for 50 years, so I'll just show my ignorance and ask--how come ATSF, GN, and NP seemed to favor the B-B locos over the A-1-A E units?

I think it is because F units were generally better on mountains. WP, CP & CNR also favored F units for passenger service.

Railroads with lines which that had gentler grades such as ACL, CB & Q, Erie, NYC, RF & P, SAL and Wabash seemed to favor E units.

SP used both Es and Fs, but I believe the E units were typically used on routes with flatter profiles like the Sunset and Golden State routes whereas the Overland Route trains were assigned F units.

There are exceptions. UP generally assigned E-units to its trains even though some of its routes had stiff grades. The Soo Line which had mostly level territory never owned an E-unit.

Then there are other railroads like the Milwaukee Road which used both E and F units on the same routes (and sometimes in the same train consists!) which would defy any generalizations.

Santa Fe was pretty even keeled with purchases of A-1-A power in the form of the E1 (which were later rebuilt into their E8m's), E3, and E6, and discounting the second prime mover, the PA. They converted some Freight FT's for Passenger Service, and then tried the F3's; finally ordering a slew of F7's. My guess is the F's were preferred over Raton, which was why they held down the Super Chief, Chief, and El Capitan. The PA's worked pretty much worked anywhere, but the E's were not favored on that steep grade, and thus were confined to the flatland trains.

Simply it came down to horsepower, driven axles, and to a lesser extent, fuel consumption. If a single E8m produced 2250 H.P. from two prime movers providing power to four motors over six axles, and sticking with the concept of two prime movers, why not get 3000 H.P. out of two units mu'ed, over 8 driven axles?

Bob

ATSF100WEST......Out

GN owned 13 E7As that they relegated to secondary train service. In 1945, GN purchased 10 E7As for Empire Builder service. In 1947, GN purchased 3 additional E7As. When they used paired E7s in Empire Builder service, they had problems with traction motors overheating in the western mountainous territory. GN then ordered 5 F7Bs to splice the E7A pairs. This arrangement was also not successful. They then relegated the E7As to non-transcontinental. On the other hand, UP successfully utilized E Units in transcontinental service. However, they generally utilized more than 2 units. I believe the Es may well have worked for GN if they have used 3 or 4 units instead of trying to get by with a pair.

Also, on the other side of the continent, SR used both Es and Fs in passenger service pretty much interchangeably until about 1971 when they basically dedicated the remaining Es to the Crescent.

ALLEN



Edited 1 time(s). Last edit at 09/02/14 22:54 by krm152.

Santa Fe's freight FTs were converted temporarily until the F3s arrived. The Es were their first passenger units and were relegated to shorter runs after the Fs and their dynamic brakes arrived.

Bill Deaver
Tehachapi, CA

I agree with the previous answers. Gearing and A-1-A trucks made the Es
able to operate at up to 117 mph (at least on paper). One advantage of
an E on a short passenger train in minimal grade territory, the single
unit could operate on one prime mover, if you had a failure of an engine.
A single E was limited to seven cars on the C&NW, which used Es, Fs, GPs,
and RSC series in passenger service. UP Es had a lower gearing and were
used in numbers sufficient to maintain a relatively high speed in the
mountains. I knew a head end brakeman who worked for UP in the 50s and
60s. He said the reason Es worked on the UP was the fact that management
would provide sufficient power to prevent the low speed traction motor
failures that occurred on other roads when speeds fell below about 30 mph.

Comparing E unit and F unit gearing is not as easy as looking at the numbers of the ring and pinion gears. The F units had 40" wheels while the E units had 36" wheels. So each revolution of an E unit driver moved the locomotive ahead a shorter distance than one revolution of an F unit driver.

Posted from Windows Phone OS 7

Remember also that F units had more weight on the "drivers" than
the E units with their idler center axles. This allowed the F's
to pull better on a stiff grade.

Another road that never owned an E unit was Northern Pacific. I rode
the North Coast Limited in 1967 and was puzzled at the time as to why
they used four F's, F9's in those days, east of Livingston, where
the flat grades were, and three F's over Bozeman and Homestake Passes
west of Livingston. I was later told the extra F east of Livingston
was to help maintain the faster speeds on the flatlands.

Nick Tharalson,
Marion, IA

ntharalson Wrote:
-------------------------------------------------------
> I rode
> the North Coast Limited in 1967 and was puzzled at
> the time as to why
> they used four F's, F9's in those days, east of
> Livingston, where
> the flat grades were.

Not so flat Glendive - Dickinson.

Best regards,

Rob L.

The Erie and the DL&W are two examples of railroads that started with F's for passengers and changed to E's. In most cases it went the other way around.

IIRC on the SP the PAs worked better than the Es for grade territory because of their GE traction motors. PAs were the preferred power for years for the Sierra and Cascade crossings, and they did a stint on the San Joaquin Daylight.
For a little while the SP would run two PAs and a PB out of Los Angeles on No. 51 in the morning and take off the lead PA at Bakersfield, turn it, and put in on ahead of the PA + PB set that came in from Oakland on No. 52 a few hours later and have the three units for the Tehachapi crossing both ways.

This is a good thread .

See also:
http://www.trainorders.com/discussion/read.php?11,3215171
http://www.trainorders.com/discussion/read.php?11,3238263