UP's box is probably one of the newest; it was built in the mid-'90's and does have Exane wire throughout.

Also, and not to beat up on another poster for repeating somethign he probably read elsewhere, but the tale about a crew member jumping off 844 and hitting the EFCO on the 1982 as it went by is fantasy, IMO. Like so many things related to this incident, there is no evidence of it, and as Preston says, the fact the 1982 was running when they backed into the yard speaks volumes.

It is indeed fantasy. I only mentioned it in an earlier thread as part of a plausible scenario for this mishap, and I identified it as such. I never claimed it to be the facts of what happened. It is not even my opinion. What difference does it make that there is no evidence of it? There is plenty of evidence in this mishap that is lacking at this point, so a lack of evidence does not prove that something that could have happened did not happen. In my hypothetical scenario, I said the person either boarded the engine or shut off of the fuel. Boarding the engine leaves open the possibility that the engine came into the yard running. And seeing the diesel come into the yard running does not exactly prove or disprove anything about how it was gotten under control.

Or that it was ever out of control in the first place. That's not been proven, either.

Nor has failure to control it.

Yes, I agree that nothing has been confirmed other than the flattened wheels. I guess that it is also confirmed that they passed their stopping point. I would think there would be a lot of informed discussion among employees about what happened, and that that would be leaking out to the general public. Maybe it will just take more time. I have a feeling that an official explanation is a long way off.

Ron, if a computer controlled locomotive actually had an unexplained runaway you assume that the operating software has gotten corrupted and you shut it down and secure it in such a way that it cannot start again on its own, until it is attended by qualified maintenance personnel in a properly secured situation. On diesel locomotives this normally requires shutting the unit down and pulling the battery switch and starting fuse, going behind the shields and opening the computer control breaker, and tagging the locomotive out of service. The person in charge will usually take possession of all the starting fuses on the locomotive so nobody else can attempt a restart.

PC

Photos posted on Trainorders yesterday show the drivers have all been removed from the 844. Also reported that they were shipped to two different shops for turning.

Yes, I understand your point, and that may have been exactly what happened. My only point was that I have no opinions or beliefs as to what did not happen such as an opinion that the emergency fuel shut off could not have played a role. I am only considering plausible scenarios that would fit the generally presented premise that the crew lost control of the diesel when it was under power and had to resort to unusual measures to get the train stopped.

Regarding the plausibility of a crewman getting off of #844 before the train had stopped in order to get to the diesel as soon as possible:

If the wheel side on 844 were the result of a last ditch effort to produce enough braking resistance to slow the diesel, it seems highly likely that there would have been uncertainty that the maximum brake effort would have completely stopped the train, or stopped it without prolonged power braking and an elevated risk of wheel slide. Therefore, it seems highly likely that someone would have gotten off the steamer as soon as the speed was low enough to do so without substantial risk of injury, and attempted to get to the diesel as soon as possible.

Once somebody got off of the steamer, I think it would have been more likely that the person would have boarded the diesel rather than trying to shut off the fuel. But of course there is no evidence of this. I am just drawing a picture. But, of course, I am not jumping to a conclusion that the picture is the truth of what happened.

Some pictures of #844 as a 4-0-4:

It's not what you know, it's who you know...844 at the GRR

Drivers have been sent to both TVRM and Strasburg for turning, so that the engine can get on the road as fast as possible according to Railspot board.

phew...they should let 844 do the pulling leave the diesel off except for braking.
report I heard the diesel pushed for about a mile. It sounds like they went thru a series of braking trouobleshooting on the fly and the last resort was to emergency the drivers risking flat spots. Sounds like they did what they had to do. They averted a serious issue, but gained flats on the 844. solveable. Now they will have to troubleshoot why it happenned.

On a computerized locomotive, can a computer malfunction keep the propulsion going or is there still an absolute need that certain MU trainline wires be energized? When the wires were going directly to governor solenoids then probably not but if they are just another input to the computer then it could happen.

And again, if the PC business can directly kill power no matter what it's one thing, but if again, it's just another computer input then dumping air might not do any good.

Steve

Steve, generally (with most computer controlled diesel locomotives) from the lead unit the PCS, the throttle handle switch 1-8, the generator field switch, a generator field decay contactor position indicating interlock, and the isolation switch can all drop out the generator field contactor and remove excitation from the generator (diesel lead unit plus trailing units) and the computer on that unit cannot bypass them. Any one of them being "open" shuts off the excitation. These devices are wired in a series string.

On a trailing unit, if pin 6 feed is hot from the lead unit, the generator field decay contactor position indicating interlock and the isolation switch can remove excitation and the trainline and the computer cannot bypass them.

The computer normally has a gate ahead of GFD that can turn the excitation OFF, based on software alarms, but that gate has no internal power source to pick up the coil of the generator field contactor, it is dependent on the feed from the other devices for its power input.

The Isolation switch is absolute, it is the last device before the GFC coil, it should drop excitation even if trainline pin 6 were shorted to a "hot" positive feed.

PC

if they do computer control correctly, the programming should be ROM stored, non-volatale memory. RAM could be at issue because it could have a higher failure rate. Railroads meet Bill Gates. I don't know how high computer failure rates are,
but the stuff is everywhere, in our cars our PC's my work lift truck....they recently changed the computer board on our lift truck. The systems on the railroads are designed more rough ready for heavy hardy on the road use. But like its said, if something can go wrong.....we now have more "stuff" inline with the operation of a locomotive, one part wrong can do things.

Its interesting like the INDY 500, you get a high speed car flinging along then suddenly smoke and its disabled into the pits, they find the problem, some cheap 50 cent washer failed. chaching

Let me ask this question as clearly as possible:

In the event of an emergency application of the automatic brake, does the PCS action to shut down the helper come directly from the helper’s sensing of the brake application; or does it come from the controller box in the cab of the steamer?

It comes from the diesel's sensing of the brake application.

PC