So then does that mean that there is no reason so suspect that a malfunction with the M.U. controller could have prevented the PCS action?

And is there any other reason to suspect that the diesel would not have gone to idle in the event of the automatic brakes going into emergency?

If the controller in the steam locomotive were to jam in a high throttle notch the emergency application should take the diesel off line after the calculated knockdown time delay. The diesel is going to stay in the throttle notch set on the controller until the PCS action takes it off line. However, turning off the generator field switch on the diesel box should drop the load on the diesel regardless of notch setting.

I wonld prefer not to speculate on the second part of the question. The download from the locomotive will show exactly what happened.

PC

UP diesels are set up with a 20 second delay after an emergency application before shutting down.
The reason is if there was a break in two near the head end and the head end stopped short, the hind end would slam into it. This gives the head end time to gain some headway.
The MU box has redundancy. Kill switch, reverse switch, throttle and Gen Field switch.

It would be interesting to see how the "kill switch" is wired. If it works by energizing the "D" solenoid feed then it probably will not shut down the engine if the rotary throttle selector has another throttle solenoid energized. In that situation it might just give you a minus 160 RPM reduction from whatever notch is set. The "D" solenoid feed normally will not shut down the engine unless all the other solenoid feeds are de-energized.

PC

After considering all of details, I cannot see a plausible explanation for losing control of the diesel. It was totally under control, assuming that all they had to do to shut it down was to put the automatic brakes into emergency.

One thing that nobody has taken into consideration is where this event actually occured. From what I'm gathering everybody seems to think this diesel was pushing out of control for 1000 miles (yes grossly exaggerated) until it blew past the train's stopping point. That locomotive could have throttled up just a mile from where they were to stop which gives the illusion this thing was out of control for miles. Yes, it takes time to slow trains down and add to that the 20 second delay that it would still be pushing and now you have the emergency application past the cameras, not before which I believe has been the general consensus. One thing that's missing from the videos is the sound of square wheels pounding the rail, not from just the 844. I'm sure there are other wheels in the train that were slid flat. Maybe not comdemnable flatspots but flatspots none the less. I really do truely believe that this has been blown out of proportion and the specifics will never be known. I do however think that new SOPs concerning operation such as all diesel helpers being manned will come about.

If there was a "like" button, I would have just hit it. I heartily agree with ns2110.

I have not heard anybody on this or any other forum express anything like that at all. Nobody has suggested or stated that the train was out of control for more than two miles.

On page 71 of June Trains there is a photo of a wheel with damage. Is that weld on the wheel tread?

It was reported somewhere that the steam team did in fact build up some weld on the drivers as a temporary measure to limp 844 to the nearest repair facility.

I would rather suspect that the wheels will be subject to various radiographic and magnetic tests to make sure they are in good order before they are mounted. I think that in emergency situations, that weld buildup can be acceptable to get the engine to the nearest shop--since there are so few shops and no other practicable way to get the work done.

Michael Seitz
Missoula MT

It'll be interesting to see what's required. IIRC, for conventional wheels (i.e.- no tires) if an emergency weld repair is done on a wheel tread, then that wheel must be condemned as soon as the locomotive gets to a shop. Hopefully 844 doesn't have to wait for 8 new 80 inch tires to be fabricated and fitted.

I could be wrong, but I hope/guess that a program at the level of UP's always has spares.

I saw no evidence of welding on the tires for the two drivers (#1 and #4) that came to TVRM. TVRM was very pleased to help our UP Steam Brethern get the 844 back on the road.

What a remarkable job by all in answering the call.
Stand tall everyone.
Ira Schreiber