Nostalgia & History > 50 years of UP Centennials

First released from EMD in 1969, the DDA40X was nicknamed the Centennial in honor of the 100th anniversary of the completion of the trans-continental railroad.
Here the 6904 is helping the San Francisco Zephyr.

Adam

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Mr-Beechcroft Wrote:
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> First released from EMD in 1969, the DDA40X was
> nicknamed the Centennial in honor of the 100th
> anniversary of the completion of the
> trans-continental railroad.
> Here the 6904 is helping the San Francisco
> Zephyr.
>

Looks like Green River, WY ... and 50 years? Wow!
> Adam

How fast would the Centennials been able to pull the S. F. Zephyr ? 

Faster than you would want to ride!

Definately Green River.

80 is their max about

dan Wrote:
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> 80 is their max about

I believe their traction motors were rated for 83-86 mph. I was in Salt Lake attending college when the 6900 arrived with the High Iron train for the centennial celebration. And I had the privilege to operate them over the 4th district on van trains back in the late 70's and early 80's.

Bob Krieger
Cheyenne, WY

in the timetable they just say 80 thanks, i had wondered

And a few stories at the century mark as well. My buddy worked with them guys headed west out of Cheyenne.

Posted from iPhone

Never get tired of Centennials. Wish UP would bring that 6936 out more though.

MILW86A

dan Wrote:
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> 80 is their max about

Don't know where you get your information but, checking the EMD Locomotive Service manual for the DDA40X model, under Gearing 59:18:

1) Ratio   3.277
2) Full Horsepower Low Speed - Nominal.  28.3 MPH
3) Full Horsepower Max. Speed - Nominal.  82 MPH
4) Minimum Continuous Speed (Full Throttle)  11.3 MPH
5) Gear Ration Max. Speed.  90 MPH

In later years timetable maximum was 82 mph, tho
EMD said 59:18 was good for more.

1973 Nebr timetable says 75 maximum for road freight
engines on passenger trains.

http://wx4.org/to/foam/maps/1-Ogle/1973-09-09UP_Nebraska45_OCR-Ogle.pdf



Edited 1 time(s). Last edit at 01/23/19 14:50 by timz.

> > How fast would the Centennials been able to pull the S. F. Zephyr ? 

> 6936 speedometer south of Speer enroute to Denver.  'Nuf said!

Hello,

There are two things going on here - there's the engines' max speed and the operating max speed and some are confusing the two.

The DP line doesn't have cab signals, so the max there will be no more than 79 mph.  That appears to be what the speedo is indicating in the photo.  But that's not the locomotive's max - that will depend upon other "on-board" factors such as wheel size, gear ratio, strength of traction motor windings, etc.  Hot Water gave the DDA40X max speeds from the operating manual.  You don't really know the actual max for an electrically-driven locomotive until the traction motors fly apart.  Thankfully, that very rarely happens since (design) engineers at EMD (in this case) would build in some margin of safety, putting the stated max speeds well below the point where the equipment would actually fail.

Take care,

Mark
  

UP mainline between Laramie and Rock Springs had a 90 MPH speed limit until about 1982. That speed was normal for the SFZ. BSB

Posted from iPhone

What year would that have likely been(when a Centennial lead the Zypher)?  Footbridge and yard tower built into depot definitely make it G.R., haircut on ground man cudda been mine and I worked there in summer/64 but don't recall the occasion altho I did ride all the DDs  and (previously)Es.

Steve Donaldson
Pacific Grove, CA



Edited 1 time(s). Last edit at 01/25/19 06:54 by SteveD.

Just noticed -- looks like one or two SP F-units
back there. Didn't know they ever got east of Ogden.