Nostalgia & History > Tunnel Motor Tuesday . . .

.   .   .   in MAY '90, on day one of my honeymoon :-), a pair of tunnel motors, spliced by a 45, were westbound with a mixed intermodal train on the Soledad Canyon line in *corrected CA.
JB



Edited 1 time(s). Last edit at 11/19/19 14:39 by 3rdswitch.

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Such an interesting photo!  But I have to ask for help.  Why are they called tunnel motors?  To my poor eyes I cannot distinguish the tunnel motor features.  

Tunnel motors have a big air intake grill low down at the non-cab end of the locomotive. 

Great shot... you must have been in heaven, a honeymoon with Southern Pacific action thrown in...

Hou74-76 Wrote:
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> Such an interesting photo!  But I have to ask for
> help.  Why are they called tunnel motors?  To my
> poor eyes I cannot distinguish the tunnel motor
> features.  

The open airway in the rear of the unit was to encourage air flow through the radiators, the idea was developed for over-heating in the numerous tunnels of the Southern Pacific RR, mostly on Donner Pass. Basically, the air comes in near the walkway through the large grilled airway, then into the fans which are in compartments marked with a white square and then through the radiators themselves near the roof and then out through the open grill work on the roof. At the time it was thought to be an obvious improvement and the SP ordered hundreds of locomotive with that open design with the routes through the tunnel being the justification, ergo tunnel motor and the T-2 designation.

Since then there has been much discussion about the cooling theory...and locomotive design moved forward without the large airway.

Iconic photo, there seems to be have been a time when they would have the noses of the trailing units pointed every which way. Seems it takes some work to have them pointed that way.



Edited 2 time(s). Last edit at 11/19/19 11:11 by TCnR.

Neat shot. Train chasing in the Soledad Cayon is fun.Bill Webb



Edited 1 time(s). Last edit at 11/19/19 10:37 by spider1319.

3rdswitch wrote:

> ... on the Soledad Canyon line near Soledad, CA.

Not "near Soledad, CA."  Soledad, CA is a town in Monterey County 25 miles southeast of Salinas.

There is no town or even a siding called "Soledad" in Soledad Canyon.  
 

Correction:  The intake was for 'cooler air' lower in the tunnels which they believed helped radiator cooling and prevented engine shut down due to over temperatures from the hot exhaust at the same level. They saw the fans were pulling in hot exhuast at the same level as the higher intake = made the situation worse..

Early version of a tunnel motor with so-called elephant ears (Steve Sloan photo) and the final product from EMD (unknown photograher). 



Edited 1 time(s). Last edit at 11/19/19 14:18 by trackplanner.

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So you lived to tell the tale 3rdswitch, I’m impressed! On the second day of our honeymoon we were driving through Davenport, CA and there was the UP local at the cement plant - I remember a DRGW GP60 for sure, don’t remember the other power but think one was in UP paint. Anyhow, my new bride gave me a dirty look and asked if I drove that way on purpose just to find a train. I hadn’t, which kept me out of the doghouse - that day. But a little later I was sure hoping the train would catch up to us. We had stopped in Capitola, I had never been there before, and I sure wanted to see a train on that bridge. No luck, but now my wife doesn’t give me too much grief if I pull over to check out a train.

Posted from iPhone

I'm familiar with the tunnel motor concept, but are there any accounts of locos in a consist overheating and shutting down in tunnels, leading to a stall and potentially sketchy situation for the crew?

tehachapifan Wrote:
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> I'm familiar with the tunnel motor concept, but
> are there any accounts of locos in a consist
> overheating and shutting down in tunnels, leading
> to a stall and potentially sketchy situation for
> the crew?

Yes very much, before and after the development of the tunnel motor. Overheating had it's days but also locomotives starving out of oxygen, which causes them to belch more smoke. During the SP days of 80's and 90's it was typical to request a reverse move out of the Donner Pass summit tunnel before entering the tunnel, just in case the train stalled out. This made sure the dispatcher was aware of the train going into the tunnel and to make sure a second train did not get too close and block backing the train back downhill. Ex employees should be able to tell a few stories about this.

dcfbalcoS1 Wrote:

> Correction:  The intake was for 'cooler air'
> lower in the tunnels which they believed helped
> radiator cooling and prevented engine shut down
> due to over temperatures from the hot exhaust at
> the same level.

Hotwater, who used to work for EMD, has suggested in old posts that the lower air intake didn't actually help *inside* tunnels so much, but allowed for a faster cool-down *between* tunnels:

"The tunnel cooling system generally ran no cooler engine water in hot desert or tunnel conditions than the standard cooling system. The big advantage of the tunnel cooling system designed was the MUCH MORE RAPID cool down rate, due to the lower cooling air intake. Thus, the engine cooling water was cooling down much more rapidly prior to entering the next tunnel/snow shed. When operating at full load in long tunnels, the tunnel cooling system eventually got the engine cooling water just as hot as the basic system."

https://www.trainorders.com/discussion/read.php?11,4415500,4415861#msg-4415861

I also understand that because the "tunnel motors" had fans under the radiators, thus blowing air up through the radiator sections rather than pulling it through like on older units, radiator sections tended to have more problems with debris being blown into them with more force causing leaks.

While I don't doubt the tunnel design helped with tunnel usage, I guarantee from personal experience in the Cascades on SP's Cascade Line they did overheat just like older units, although I believe not as fast. 

If you look carefully at any Dash 8 GE or newer, you will see a similar concept in place.  Really.

Nick Tharalson,
Marion, IA

As additional information, the EMD design of the "Tunnel cooling System Modification", as it was officially named/called, was strictly for faster cool-down upon exiting the many shorter snow sheds and tunnels on the SP Donner Pass line. The "Tunnel Cooling System" did NOT provide any real benefit in longer tunnels, at slow drag speeds.

Interesting story in the referenced TO post about the T-2 desgination and Nixon era price controls, really puts a date on things.

I'm told the worst accident in railroad history occurred when a train stalled in a tunnel. This was during World War I in the Italian Alps, and everyone in the train (1500 souls, or so) died of asphyxiation. Little is written of the incident, because of wartime censorship. Perhaps someone knows more details than I do.
Winston Hill