How do railroads find a bad wheel?

At slow speeds, you will normally hear some squealing of flanges and popping of rail joints. That doesn't necessarily indicate a problem with the truck, axles or wheels.

 

Railroads use WILD detectors (wheel impact load detector) to determine if a wheel is out of round.  If you have ever heard a train pass and a car or two had flat spots on the wheels, a WILD detector is designed to catch the defect before the wheel actually starts making the "thump, thump, thump" sound you hear as the car goes by.  These devices can also detect if the trucks on a car are "hunting" (basically moving from side to side).  These type of defects can cause cracks and hidden flaws in the rail, eventually leading to a failure in the rail and, possibly, a derailment.

 

Judging by how much private car owner's wheel replacement costs have skyrocketed since general deployment of the WILD detectors, they must be doing a heckuva good job at early detection.

 

Curt

My father spent a lot of years for the Pittsburg and Shawmut RR scraping cast steel wheels and tru-ing (turning) wheel sets to the proper flange dimensions.  Still part of the industry.

I took these pictures at Conway Yard (NS) a few year ago. 
The wheels are turned still on the unit.

Flat spots are a concern, actual tapper of the wear surface is the most important part of the wheel.  IMO.

   Is there a defective bearing detector?

Well, I hope CSX or NS reports such conditions to Amtrak on its trains. On the Lake Shore Limited from New York to Chicago back in December, there was a thump throughout the coach car I was in that seemed to match time/distance of a wheel revolution. Didn't notice in other cars when I was walking through the train. Very annoying, to me at least. Wheel was out of round or flat-spotted?

David

Ok Silly question here. HOw do these small round bits cut into the steel?

Do they spin at a high rotation? Are they fixed and the wheel spins?

 

Inquiring minds would like to know!

 

There are a two systems out there: RailBam (Bearing Acoustic Monitor) and TADS (Trackside Acoustic Detection System). Both systems "listen" for bad bearings.

Actually there is a simple method of detecting developing cracks. View the wheel with a thermal imaging night vision device This was discovered by Night Vision Labs at Belvoir Va. in 1970. We tested it on tanks to determine developing torsion bar failure and railroad wheels. It works for bearing failure as well. If the bearings are not up to snuff there will be a differential in the temperature of the wheel. The night vision devices can detect changes in temperature of 1/1000 of a degree. Adjusting the CRT will show different colors on the screen.

That could of been a hand brake left on, or if the engineer had a lot of air set, that car was just squeeling. Since you said they were approaching the yard, they were probably slowing down and depending on the weight of the train... a normal reaction from cars. From what you describe, sounds more like a hand brake.

RailBam (Bearing Acoustic Monitor)

 

  Is this car or trackside mounted?

Trackside http://www.trackiq.com.au/railbam.html

The accoustic bearing detection devices are normally wayside.

 

Curt