When you put an engine like 844 in reverse and yank open the throttle, think of the weight of the drivers and valve motion that has to stop and reverse. It's not going to be an instant reversal. This kind of crap is cannon fodder for the Hollywierd crowd.
In addition, you stand a good chance of blowing the cylinder heads off, blowing out the packing or snapping a crankpin and stripping the locomotive.
I can't honestly think of an instance where you would want to do this. To begin with in all my time running a steam engine and some of it running with an MU box, I would be scared to death to even do it for fear of blowing everything out of the water.
Whether or not the story ever comes out, I have gone over it many times in my mind and have a scenario that I think happened.
Since my opinion and cash will get you a coffee, I'll keep it to myself. This thread has gotten enough attention.

Dear Lincoln Penn,

You stated the following "The independent brakes are applied with 40 psi when fully applied. If the rail surface is in good condition (i.e. dry, no wet leaves, frost or weeds), they won't slide." I would like to know more about how you came to this conclusion as my experience with locomotives shows that if you are at the maximum independent pressure you will slide the wheels even when the best coefficient of friction exists between the wheel and the rail. For the record I spent time running at both Grand Canyon Railway and the Nevada Northern.

Robby Peartree

Can we just knock this thread in the head? All it seems to be is a bunch of armchair rail nerd foamer *experts*(except for a few of you, and you know who you are) and there are other places on the internet for those dateless critics to pontificate about what happened and share their expertise learned from hours of internet research and yelling at innocents to "get out of the frame" during runby's.

Quite frankly, the UP spent their own money to fix the thing to run in the first place, spent their own money to staff the program, and spent their own money to fix it when something went wrong (and did so in a very, very timely fashion). It ain't nobody's business, and, unless the FRA sees fit to do something, it is UP's issue alone. Since we don't run our little logging lokeys with mu boxes and SD 40s behind them, I really don't care.

Good job by the UP's crew for a quick fix of flat spots on driving wheels, which would only have gotten a light cussing from the shop forman in the old days, because flat spots did and do happen all the time. Just not one video to the Road Queen.

A while back, I started a thread asking when power brakes on locomotives were first introduced. My understanding is that reversing the locomotive was standard stopping practice when running light and during switching. The only other option was hand brakes. It is true that this reversing to stop is kind of a Hollywood thing. But those movies are often reflecting an early era, so they may be depicting actual practice. But once you have power brakes on a locomotive, I wonder if there is any reason to use reverse for stopping.

Here is the question that I posed in that thread that never got answered. I also posted it earlier in this thread. It is a physics question and it has nothing to do with #844:

Which of these three scenarios would produce the greatest retarding force?

1) Independent applied just short of wheel slide.
2) Independent fully applied with wheels sliding.
3) Engine running in reverse to brake forward movement.

> When you put an engine like 844 in reverse
> and yank open the throttle...

As others have already mentioned, if you try it that way, you're going to break something. I think that would be a risk on just about any locomotive. Even just getting the reverser too close to center can cause things to start bucking. If you were to do it at all, you'd probably want to open the throttle slowly.

> It's not going to be an instant reversal.

No, it's going to gradually slow down, so the wheels are sliding but still rotating, reach the "zero point" for an instant, and then the drivers will start spinning backwards. What I don't see as being likely to occur is for the wheels to stop rotating and create a flat spot. As I mentioned, I guess that could theoretically be possible if you centered the Johnson Bar. Again, why you'd do that is a total mystery.

Would they stop rotating and make flats spots with the independent brakes on full? Yes, quite likely. But the comment suggested it was due to running her in reverse.

> This kind of crap is cannon fodder for the Hollywierd crowd.

True, but as was also mentioned, most Hollyweird crap is loosely based on fact. They did the old "spin the drivers in reverse with sparks flying" since that's what happens if you put it in reverse and open the throttle. It's about as realistic a scenario as all the high speed car chases you see in TV shows today, but there is a grain of truth in there.

Something to remember about the "reversing" thing. Ed came from the colorado narrow gauge world, that was standard practice back in the olden days. It worked back then amongst the narrow gauge railroads and maybe he thought it would work on the full size thing.
Regardless of all the speculation there are a few things which are irrefutable. First, the wheels slid and there are two means to prevent this, bail and self bleeding mountain cock. Second, reversing the locomotive would not have caused flatspots. Third, the UP dumped the blackbox and there was no record of the locomotive being "told" to throttle down by the control box.


John

Ron: Your answer is: No. 1.

Robby: A locomotive that slides it's wheels under regular circumstances has a defect. It may be one or more of the following: Incorrect independent independent brake cylinder pressure, faulty feed valve, faulty air gauge, incorrect lever ratio, incorrect brake piston travel, incorrect pin placement in one or more levers. It is not normal and should not be accepted as such.

Wheels moving in one direction cannot change direction without stopping, even if only for a split second. Reversing one, especially a big one, under certain circumstances, can and will produce flat spots, albeit small ones. Can't argue with Mother Nature.

Dickens was not running the locomotive at the time. The "back in the day" narrow gauge practice was, indeed, long, long before his time, anyway.

Anybody can look good when things are going well. What separates people is how they react when things suddenly fall apart. That is why the aviation industry spends so much time and effort training pilots how to react to so many different failure scenarios, some of which may seem far-fetched. There are too many examples to list.

There are several posters in this thread who have the background, experience level and contacts to find out what happened, and have done so. This makes some other people uncomfortable, to the point that the subject can no longer be adequately and intelligently discussed. So be it.

I am in agreement with those who say "move on." The pertinent people in this incident have learned some valuable, if expensive and embarrassing, lessons, have done their penance, and life goes on, chagrined but smarter. If nothing else, they know what not to do now. Those in the industry who can learn from this, will. Others won't. Nothing new, there, either.

The end.

Some of us would still like to know what happened. There is no right to know let alone need to know. Just a curiosity to know.

Steve

Thanks Lincoln Penn, for confirming that item #1 is the correct answer. That would have been my guess. But what about comparing item #2 to #3 ? Which produces a quicker rate of deceleration: A locked and sliding wheel, or a counter-rotating wheel?

A wheel spinning in reverse against a rail is producing zero traction or friction. Though not 100% accurate, as such a spinning wheel will damage dry rail and/or the railhead, that's the theoretical efficiency involved.

A locked wheel invokes friction between the railhead and the surface of the wheel. When we consider that the actual contact between a perfect-profile wheel and rail is on the order of the size of a quarter of 50-cent piece, you can understand how flat spots can develop so quickly, and why a flat spot bigger than a dollar bill compels fright from operating personnel.

The fact that maximum braking is exerted precisely before a wheel locks up is the driving mentality behind the anti-lock braking systems in many automobiles today. (Well, that and the fact that skidding wheels hydroplane, go where you don't want them, don't stop the car as well, etc.)

I agree 100% Mr. Penn. I think this thread has developed into a giant p***ing match about who knows more about what. Those who have experience in the matter show it in their posts, and for those that don't (specifically, ones that think they do) it is quite obvious. This thread has spiraled on and off topic, I believe the moderators should consider locking it.

What's done is done with 844. There is no sense beating a dead horse, the drivers slid and flat-spotted due to a combination of errors. It was truly a unique accident that no one could have accurately predicted, regardless what some of these "armchair engineers" have to say about it, they weren't there. What should be taken away from this is a learning experience. Just be glad that nobody was injured and damage was limited to the tires and the nerves of a few UP employees.

My .02,
DC

I too feel this thread has devolved to the point where it serves no real purpose, but I did want to bring up a point which has not been mentioned on the spinning wheel issue.

A steam locomotive driver has its tyres shrink fitted. If that wheel is being pushed along, spinning against the direction of travel, a tremendous amount of heat will be generated. If the condition persists very long, it is entirely possible the tyre will expand sufficiently to loosen on a wheel center... combine that with a curve and it introduces risk of a catastrophic failure, likely including a derailment.

Note that a similar condition exists when a driver is being spun excesively due to heavy grades, slippery rail, excessive tonnage, or just plain bad engine handling.

You simply don't want to go there.

Regarding what happened on UP, information may eventually be released. If the problem was internal to the diesel, it's likely EMC will release service bulletins or otherwise ensure the cause is eradicated.

It affects only a very small part the tourist railway/ museum industry, namely those who MU with diesels. I suspect UP is far more likely to share critical information with them, than a mob of foamers who have no real need to know!

Running a lone MLW S-3, this information doesn't affect my engine's safety.

Regarding UP's handling of a bad situation and rapidly making the needed repairs, they are to be wholeheartedly congratulated!

Steve Hunter

I think this topic has been discussed/analyzed/flogged to death. It has degenerated into what is essentially and argument, so for now, I'm going to lock the topic. If really new information comes to light, feel free to open up a new discussion.