O.T. ~ Metal fatigue, writ large!

JoeE. · Feb 17, 2018

Thought some of you may like to see this.

Had a train leaving our yard today. It stopped to perform some air tests, and when it started moving ahead again, it only made it about 10 feet and went into "Emergency"... which is a railroad phrase for telling you that the brakes all applied for some unknown reason.

Well, a little sleuthing and they found this.

Hopper car torn in half... - YouTube

.... and this is how they cleared the track so we could go about our day. Sorry about no sound... someone poked the wrong button on the phone...

Car won't roll... - YouTube

286,000 pound capacity car, full of soybean meal... tore the whole north end out of the car. It only had about 40 cars behind it.

There was previously unseen fractures in the steel underframe..... about halfway broke in two, already... lucky it happened here going 2 mph instead of out on the main line going 50!!!!

adama · Feb 17, 2018

Maybe post it up so we can then, that linky is dead

Chip Chester · Feb 17, 2018

Interesting vid. Can you please ask them to hold the phone sideways next time? It's the 21st century and all...

PeteM · Feb 17, 2018

Interesting. Thanks, Joe.

DDoug · Feb 17, 2018

I like it !

So not only did the bottom go out, the drag ripped the back truck
out from under it.

How frequent (if any) is there any inspection ?

Good enough to spot the cracks ? Maybe each year ?

BTW was it very cold out ?

JoeE. · Feb 17, 2018

Chip Chester said:
Interesting vid. Can you please ask them to hold the phone sideways next time? It's the 21st century and all...

Will that make a difference? I held the phone the same in the top video as the person held it in the second video.

JoeE. · Feb 17, 2018

digger doug said:
I like it !

So not only did the bottom go out, the drag ripped the back truck
out from under it.

How frequent (if any) is there any inspection ?

Good enough to spot the cracks ? Maybe each year ?

BTW was it very cold out ?

The truck is what got left behind.

Inspection is not comprehensive enough to detect flaws like this. It would have to be glaringly apparent for anyone to catch something like this.

In part of the video, I got up under the car and got close enough to show the part of the center sill of the car frame (Square metal tube looking thing) where it broke in two. Some of the fracture face was fresh, some was old break... rusty instead of silver. If you pay attention you can see some of the other welds on the steel just pulled apart.. and most of those that I remember looking at had little to no penetration... someone was in a hurry to get done, from the looks of it.

DDoug · Feb 17, 2018

I recall talking to a crane operator at a tank car place in Greenville, pa.

They were building 21 a day, running 3 shifts.

Piecework brings out the worst in people cheating at welds.

Chip Chester · Feb 17, 2018

JoeE. said:
Will that make a difference? I held the phone the same in the top video as the person held it in the second video.

It should, yes. You can test it out fairly quickly. Not being snarky -- should make for a more watchable vid, with the aspect ratio more closely matching the YouTube format.

Tonytn36 · Feb 17, 2018

Interesting. If you like this kind of stuff, hop over to the NTSB.GOV website and check out the accident report on the GE engine uncontained engine failure. Lots of good info on stress cracking and inclusions, etc. A 53 lb piece of that Inco 718 2nd stage turbine went 2935 ft and through a UPS warehouse roof. NTSB/AAR-18/01 is the report number. If you want technical details, go on the database and search that report number and you will get all of the detailed individual lab reports for it.

Mark Rand · Feb 17, 2018

It'll buff out.

What happens to recover the waggon and the soya bean meal that was in it?

JoeE. · Feb 17, 2018

The car will be vacuumed out by some big truck, I'm sure.

The car will be cut up for scrap where it lays...

EPAIII · Feb 17, 2018

Time was every rail car had a beam running from one end to the other and the couplers were attached to it. The wheel trucks were mounted to it's bottom and the car was mounted on top of it. Structural integrity first, then the rest.

But somewhere down the line some smart ass engineer figured out that they could eliminate that beam and use the skin of the car to hold it together. I think the oil tankers may have been the first to be made that way: at least they were the first ones I noticed. And then other types, like hopper cars where that beam was just in the way. I am sure that saved a lot of money and weight. But it makes the body and every weld and joint in it a lot more critical. For the most part this works just fine. But we are probably lucky not to see more of this.

I also wonder about coupler failure. A coupler near the head of the train can be pulling 100 or more cars. I would love to see the stress analysis on them.

DDoug · Feb 18, 2018

EPAIII said:
Time was every rail car had a beam running from one end to the other and the couplers were attached to it. The wheel trucks were mounted to it's bottom and the car was mounted on top of it. Structural integrity first, then the rest.

But somewhere down the line some smart ass engineer figured out that they could eliminate that beam and use the skin of the car to hold it together. I think the oil tankers may have been the first to be made that way: at least they were the first ones I noticed. And then other types, like hopper cars where that beam was just in the way. I am sure that saved a lot of money and weight. But it makes the body and every weld and joint in it a lot more critical. For the most part this works just fine. But we are probably lucky not to see more of this.

I also wonder about coupler failure. A coupler near the head of the train can be pulling 100 or more cars. I would love to see the stress analysis on them.

"A ton of freight 470 miles on 1 gallon of fuel"
Fuel Efficiency - CSX.com

You would rather they burn more fuel ? And put more on a rubber
tired truck ?

Super singles on trucks, thinner steel on cars, etc.

Modelman · Feb 18, 2018

EPAIII said:
Time was every rail car had a beam running from one end to the other and the couplers were attached to it. The wheel trucks were mounted to it's bottom and the car was mounted on top of it. Structural integrity first, then the rest.

But somewhere down the line some smart ass engineer figured out that they could eliminate that beam and use the skin of the car to hold it together. I think the oil tankers may have been the first to be made that way: at least they were the first ones I noticed. And then other types, like hopper cars where that beam was just in the way. I am sure that saved a lot of money and weight. But it makes the body and every weld and joint in it a lot more critical. For the most part this works just fine. But we are probably lucky not to see more of this.

That's all well and good, but this car design retains the "beam", technically called the center sill. That is what broke, you can see the broken end just over the inboard axle at 0:31 in his first video.

Looking at the car, it is not a current design, and while I can't read the built date, likely dates to about 1975 or '76, now over forty years old. The federal limit for age of car frames is 50 years, and pull-aparts like this are exceedingly rare.

Dennis

DDoug · Feb 18, 2018

EPAIII said:
some smart ass engineer

Huh ?
"smart ass" does not equal "Smart".

cnctoolcat · Feb 18, 2018

A GE AC4400 locomotive can exert about 200,000 pounds of drawbar pull starting a train, so a pair of them exert 400,000.

...which is about the tensile strength rating on the cast-steel couplers, so if the train doesn't start moving, it's real easy to break a coupler - or more commonly a coupler knuckle.

Mountain railroads really have to pay attention to these limits, that's one reason they use pushers in the middle or rear of the train...it's important to distribute the drawbar pull just to keep the train together.

DDoug · Feb 18, 2018

cnctoolcat said:
A GE AC4400 locomotive can exert about 200,000 pounds of drawbar pull starting a train, so a pair of them exert 400,000.

...which is about the tensile strength rating on the cast-steel couplers, so if the train doesn't start moving, it's real easy to break a coupler - or more commonly a coupler knuckle.

Mountain railroads really have to pay attention to these limits, that's one reason they use pushers in the middle or rear of the train...it's important to distribute the drawbar pull just to keep the train together.

You can always tie (3) of them together for 12,000 hp.

Or using Harris locotrols, put (2) in front, (2) more further back,
on and on till you use (8).
"The record-breaking ore train from the same company, 682 cars and 7,300 m long, once carried 82,000 metric tons of ore for a total weight of the train, largest in the world, of 99734 tonnes. It was driven by eight locomotives distributed along its length to keep the couplings loads and curve performance controllable."

O.T. ~ Metal fatigue, writ large!

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