Another thread concerning junked railcars got me to wondering. Since freight cars have all apparently gone to roller bearings instead of journals, does the problem of “hot boxes” still exist? I would assume it does, which leads to the question- how often are the roller bearings lubed? Who does that?
Thanks!
Erik
Here in Brazil I know that EFVM and EFC uses “hot box” detectors along mainline. I think the roller bearings are sealled and do not need to be lube, but they have a life-time to be changed.
There are plenty of defect detectors along the right of way which you can hear reporting on a scanner. If a bearing is hot, then the conductor grabs some tempil-sticks and goes back to find it, if what we read on the forum is any indication.
FRA regulations require trains to be inspected by hot box detectors every 50 miles. If the train has not been inspected by a detector after 50 miles the train must be stopped and inspected by the crew. For this reason most Class I’s install their detectors 25 miles apart or often in a closer spacing, to allow for a detector being under repair. Some Class I’s are now implementing detectors at 15 mile spacing between detectors, which is all well and good…now if they would only have set off spurs where the detectors find hot journals that have to be set off.
Overheated bearings do happen, but they are relatively rare. Usually what the detectors catch are hot wheels from sticking bakes.
Hot box detectors are widely used and have become more sophisticated as the years pass. Once upon a time, they just spit out a papar strip chart that showed the bearing temps as the train passed. The dispatcher had to read and interpret the tape and then talk to the crew if something was amiss. Now the detectors automatically compare axle to axle and side to side to look for significant differences. They can still be fooled and “false positives” remain a problem.
The difference between friction and roller bearing failure modes is that a friction bearing will run hot and smoke for miles and miles before a burnt off journal occurs. A roller bearing can go from cool to burnt off in a matter of a couple miles. So, placement of detectors is designed to reduce risk, not eliminate it. It just isn’t practical to place wayside detectors every couple of miles. Perhaps on board detection will be a side benefit of ECP braking, someday.
There are other wayside detectors that are being investigated to reduce burn offs. There are acoustic detectors that “listen” to the bearings as the train rolls by to identify bad bearings by looking for fundamental frequencies such as when the each roller passes a spot on the inner or outer race. There are impact detectors to find flat, built up, or out of round wheels. Not only does the track and concrete tie not like high impact wheels, the bearings aren’t too happy about impacts either!
Finally, freight car roller bearings have been NFL (no field lube) for many years now. The seals are good enough that no additional grease is needed between installation on a wheelset and the time the wheel needs to be replaced due to wear.
And fireboxes on steam engines. [:D]
Seems like I read once that at one point there were “smoke bombs” (for lack of a better term) in the roller bearings. When things got hot enough, it would trigger the smoke (and smell) so the crew in the caboose could detect it (wait - I answered part of my own question…)
UM - frequently paired with the HBD’s are impact detectors, thermographic heat scanners, dragging equipment detectors and on Uncle Pete, they put some of those detectors on-board![8D]