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mtrails
07-25-2005, 12:49 AM
I was just curious, and maybe some of you experienced rail persons could answer this:

I was driving down a frontage road along side of a train doing 60, and spotted a covered hopper rocking and wiggling pretty good. It really stood out from the other hoppers which were steady as usual. As I caught up to it, I noticed the trucks were swiveling back and fourth between the rails. My eyes got as big as baseballs! I've been alongside several trains, and never noticed such a severe action, especially of the trucks. Is this okay? Normal? And if this is a problem, how is it noticed, unless you are along side the train while it's moving?

LAHDPOP
07-25-2005, 05:13 AM
I think it's called "truck-hunting." It's not normal, but it's not extremely uncommon, either. I had heard of it before, but the first time I saw it I was shocked at how violent it was (I was standing trackside, and quickly moved farther away when I saw it coming). It was a tank car, and I was just sure it was going to leave the rails as I watched. I wish I could tell you the technical explanation for how it starts, but I don't know.

EDIT: Yes, it's called truck-hunting. It seems it's especially likely to happen to empty railcars, with worn suspension components, at high speeds. If bad enough, it can cause wheel-climb, and derailment follows.

Looks like as of a couple of years ago, the FRA was looking into a truck-hunting detector: FRA Doc (http://www.fra.dot.gov/us/content/1447)

And here's a report (almost ten years old) of a derailment caused by truck-hunting: TSB Report (http://www.tsb.gc.ca/en/reports/rail/1996/r96h0021/r96h0021.asp)

Super2000
07-25-2005, 05:16 PM
I was reading an article about this recently; maybe I can track it down again.

Basically, there's work being done on trucks that don't hunt. Also, you don't really want to say that a car drives like it's on rails - that could mean that it's noisy and shakes a lot. :D

mtrails
07-25-2005, 11:08 PM
I had heard of it before, but the first time I saw it I was shocked at how violent it was (I was standing trackside, and quickly moved farther away when I saw it coming). It was a tank car, and I was just sure it was going to leave the rails as I watched.
Thanks for the research about it. Truck hunting seems to me, more dangerous than duck hunting. :P

When I got up next to this party on wheels, I sped up to get away from the possible derailment that was in my mind. As I reached the front locomotive, I was wondering what I could do to relay to the conductor to slow down or something (I was on the train's left). Naturally, of course, the road and rails became farther from each other. When I got home, I wanted to call BNSF, but didn't know how to obtain the number. The website has a number for emergencies, and well, it wasn't exactly an emergency... hence the thread here.

Also, you don't really want to say that a car drives like it's on rails - that could mean that it's noisy and shakes a lot.
My car is noisy and shakes a lot. So what? :D You know, with all the railfanning I do each week...

mtrails
07-28-2005, 11:23 PM
I had the opportunity to meet an MRL Engineer, and I spoke with him regarding truck hunting... I asked him who to report to, and he told me, "though truck hunting is common, it doesn't happen often enough to be a problem. I haven't been aware of a derailment caused by it, though I know it does tend to occur." Basically, he told me nothing would be done about it, but he would look into the car, and check it's maintenace history, and suggest to have it checked out. He also told me that truck hunting is usually induced by passage over bumpy, or slightly out of guage rails, generally over speeds of 55 mph, and it could happen to any car, and if the train changes speed, it usually goes away. He also included to tell me, that if a train travels between 13 and 20 mph constantly, a number of cars will begin to harmonic rock, which could put serveral cars on the ground.

I referred him to RP.net to view my photos, and in return, he gave me his personal website. http://geocities.com/mtrrengr/

It's pretty cool, and he's even got a recent photo of a new SD70ACe that will be in MRL colors very soon. (see Jun)

Thanks Mike.

Jeremy

View my photos: http://www.railpictures.net/showphotos.php?userid=4820