......if it was a diesel malfunction, what exactly does it have to do with the operation of the Steam program?

...now the run-away box car, that's just pure sh*t luck - could have been any freight car on their road...guess if that leads to a shut down of the steam program, they better just shut down the whole railroad.

Depends on what failed. If it was the engine itself then the answer is nothing. If it's the MU Controller in the cab of 844, then it has everything to do with the steam program.

Not assigning blame anywhere, just pointing out facts that it's possible the MU Controller failed.

I shouldn't add to the speculation here but, why was the diesel under power with that short of train? Are they afraid of running out of fuel in 844?

My guess would be insurance. UP is a busy railroad, and it would cost them a fair bit to have a stalled steam locomotive tying up their mainline. You throw the diesel on there and you can keep that train moving.

I think the point was why was it running, not just ideling. When I was on board a few weeks ago during the Shiloh Run they made a big point about how 844 was doing all the work, the diesel wasn't helping or applying any power at all, and it was just there for braking assistance, and to push if their was a mechanical malfunction, and then we see this....

This is assuming they had control of the locomotive, which is clear they did not.

On the contrary.

At this point it is far from clear what happened and whether or not the crew did or did not have control of the diesel, whether or not there was a mechanical or electrical failure, or human error. Or a combination.

As PCook said on Thursday, a download of the diesels event recorder should tell the tale. I've done a bit of locomotive control wiring, but don't want to speculate myself on what did or didn't happen. Too many variables, and I wasn't there.

I doubt that this will be the end of the UP steam program. In the big picture, this should be a mere speed bump. What WILL happen is a very thorough review of the incident, and perhaps some changes in some of the operating practices. As for the MU controller itself, I'm sure they will go over it and figure out several new ways to shut down a trailing diesel. Of course, if there was a fire or some sort of cable (or wiring) failure, the wrong two or three wires shorting out to each other could keep the diesel online.

Again, lets wait for the black box download and an official statement from UP.

Trailing units are dependent on pin 6 on the trainline being energized in order to pick up their generator field contactors (GFC) so they can produce power. Pin 6 is energized in notches 1 through 8, it is not energized in idle. The download will tell the story.

PC

Obviously the best solution would be to ban these inherently dangerous diesel locomotives from the railway and revert to steam.

;-)

I suspect that EDM has correctly identified a likely result:

"As for the MU controller itself, I'm sure they will go over it and figure out several new ways to shut down a trailing diesel." (Quote from third posting above)

Shut off the generator field switch. This will take the diesel out of power despite any PCS delay.

PC

But the question is really two-fold.

One is to find the cause of the diesel remaining in power (if that was the case but anecdotal evidence suggests it did).

But secondly, were the correct steps followed in this event both to nix the diesel propulsion and get the train stopped and could the wheel slide have been avoided.

Steve

Has this kind of failure ever happened to a trailing diesel operating in M.U. with other diesels? If not, could it happen?

Don't jump to the conclusion that this was a "failure" of a component or system. Most modern diesels have a 20 second delay on the PCS knockdown so that if you have a break in two near the front of a heavy train you can stay in power and get away from the tail end of the train rather than having it run into you. If they made an emergency application and the diesel box was still in a power throttle notch the diesel would keep right on pushing for 20 seconds.

PC

Aside from what may or may not have happened with this event in Texas, I am just wondering if there is any precedent for a controlling unit in a M.U. diesel consist losing control of a trailing unit such that the trailing unit cannot be idled or taken off power mode through the M.U. control. I have never heard of such a thing happening. Has anyone else?