Train car - what is this?

[JHZR2]

Amtrak passenger car, looks like some kind of abs setup to me (these trains have MASSIVE inboard disc brakes). Not sure why it would be needed though...

Ideas?

 

[scurvy]

It's to ensure the wheels don't skid - halfarsed ABS, if you will. Only a couple inches of skidding and you'll anneal a dime-sized spot on the wheel, which will create impact loading every revolution and fairly quickly crack the wheel.

 

[XS650]

Looks like an ABS setup to me too. They are used on some train cars to improve stopping. A locked up wheel on a train car isn't good for wheel wear.

FWIW, The AP Class EE marking is the wheel bearing designation.

 

[JHZR2]

Interesting. That was my first guess, but I kind-of thought maybe trains don't care about lockup/skidding.

Thanks!

 

[LoneRanger]

Seems like skidding would be common place with the tiny contact point of steel-on-steel of a train wheel. How do they NOT skid?

 

[carwreck]

Looks like a "AP" bearing axel end cap with speed sensor. "EE" is bearing rating.

http://www.docstoc.com/docs/46137936/ATTACHMENT-P2-TECHNICAL-SPECIFICATIONS

http://www.timken.com/en-us/solutions/rail/Documents/AP- Outboard.pdf

 

[Bill in Utah]

Speed sensor.

Just a bigger one than on our vehicles.

They care about skidding a LOT. Just a slight amount causes flat spots which kill a lot of things.

Weight prevents a lot of skid. Special sand is used in certain conditions to assist with traction.

 

[MNgopher]

Skidding is a huge deal for rail cars / wheelsets. You know that thud, thud, thud noise you sometimes hear when a freight car rolls by? That's a flat spot on a wheel set.

That flat spot on a passenger car can become a major ride nuisance. Worse, it can lead to cracked rails (think about how that would cause an impact point versus smooth rolling...).