• Hot Bearing Detector

  • Pertaining to all railroading subjects, past and present, in New York State.
Pertaining to all railroading subjects, past and present, in New York State.

Moderator: Otto Vondrak

  by Fireman43
In regards to Ohio derailment regarding the ‘possibility’ a hot bearing causing the accident ,a few questions .

What types of anomalies would a detector pick up?

What is the SOP the crew would follow when a detector activates?

Does the crew receive this alarm directly or is it relayed from the dispatcher?

  by Bracdude181
Here in North Jersey, whenever a detector finds a problem it broadcasts it over the radio and anyone in the area listening to that frequency will hear it go off.
  by jurtz
There is a lengthy discussion (actually two of them) on this underway at the trains.com forum:


This is what I picked up from there:
  • Hot Box Detector (HDB): Measures the wheel bearing temperature relative to the ambient (air) temperature. If an anomaly is detected, the HDB plays a radio message instructing the crew to stop and inspect the train. This is the type of detector of most interest in the OH accident. If you are interested in the thresholds used by NS, see the preliminary NTSB report, just out yesterday (link below, easy read, only 4 pages).
  • Dragging Equipment Detector: Self explanatory as to what it is looking for, and also requires train to stop and inspect if a problem is detected.
  • Excess Height/ Width Detectors: Looks for loads that have shifted outside the allowable envelope. Also requires a stop and inspect when triggered.
  • WILD (Wheel Impact Load Detector): These are basically looking for wheels with flat spots. Results are not reported to crews, but are sent back to RR mechanical departments for evaluation and scheduling of repair if necessary.
Again, this is a summary of what I read over on Trains. I'm sure there are variations between RR's as to how these are deployed.

NTSB Preliminary Report: https://www.ntsb.gov/investigations/Doc ... BAgXU_R2b8
  by eolesen
Yup, that's pretty much it. There should be a radio readout from the HBD after the train passes with the axle count and any anomalies detected.

I'd assume there's also a data hand-off to the 24/7 operations center & dispatch for both axle count and anomalies, but again, that's just an assumption on my part.
  by Fireman43
Blaring Headlines today with the NTSB
saying all accidents 100% preventable .!!!!
And how is that ?

Saying the crew was in process of stopping the train
  by Erie-Lackawanna
It was a stupid comment intended to grandstand. All accidents are 100% preventable. But the cost at which that prevention can take place is highly prohibitive in many cases.

  by BR&P
Did you watch the conference video? I didn't take her to mean all incidents are immediately 100% preventable. I think her point was we learn from each situation and see how things can be improved. Which has been going on for over 100 years. I'd guess there used to be more railroad collisions in a day than we now have in a year. Ditto employee fatalities. There have already been great strides made in tank car safety with heavier shells, head shields, shelf couplers, protection for valves, etc. You could probably take each of those and go back to identify one or two disasters which led to that modification. No doubt more changes will emerge from this disaster, which will prevent or lessen the next time.

I thought the woman was pretty sharp - she came across as really knowing what she was talking about rather than reading something somebody had put in front of her. She resisted the media's attempts to get her to speculate on specifics, and kept politics out of the discussion.

And yes, the crew WAS in the process of stopping the train when it derailed.
  by NYCRRson
Hot Bearing Detectors used to be the human beings in the signal towers along the track. They had special hand signals to tell the crew in the caboose if the train had a problem.

Pinching your nose and pointing to the wheels meant something was hot (a bearing). At one time they had "stink bombs" in the journal box that would smell something awful when they got too hot.

Holding one hand palm up and moving your other hand palm down above it from back to front meant a brake was sticking and the wheels on a car where sliding. Sliding wheels could overheat and cause problems.

On the NYCRR there was a hot box on an eastbound freight in Syracuse NY about 1944, the axle end burnt off and the train derailed and destroyed the SS (Signal Station = Signal Tower) and sadly killed the tower operator (The Human Hot Box Detector).

North of Philadelphia (Frankfort Junction) a Northbound Pennsy Passenger train (loaded with people, it was during WWII, Labor Day 1943) had a hot box, the tower operator spotted it and called the next tower ahead to drop the signal and cause the train to stop. Too late, the axle failed and the train derailed. The heavy coaches overturned and took out a signal bridge and some of the catenary supports, large loss of life. Same spot as the Amtrak train went through the 40 mph curve at 90 mph and derailed and killed some folks in 2015.

https://en.wikipedia.org/wiki/1943_Fran ... rain_wreck
  by eolesen
Maybe UP is on to something with their ground based conductors who can do a visual roll-by inspection...
  by tree68
It's reported that the two defect detectors previous to the derailment saw rising bearing temps, but not enough to trigger alarms to the train.

Video from a doorbell cam in Salem seems to indicate that there was a problem there.

It's been suggested in the Trains threads that acoustic detectors might have picked up noise from the failing bearing. But there are none on that line. Probably something you're going to see added to the suites of instruments at the detectors sooner rather than later.
  by NYCRRson
Correction, in the Frankfort Junction hotbox derailment (PRR Northeast Corridor 1943) the engineer of a switch engine working a nearby track (the railroad was 6 tracks wide in that area) saw the smoke/flames and called the next tower via a track-side phone (no cell phones then) and told the tower operator to stop the train, but it was too late.

None of about a dozen other trains that passed or were passed by the accident train in the hour before the accident saw anything. And no definite cause to explain the overheating of the axle journal was found.

Read the ICC report, very interesting, they determined the temperature the axle journal reached from the the color of the overheated metal. And how far into the metal the overheating reached with "photomicrographs" (microscope pictures of the broken axle metal).
  by BR&P
Was that 1943 derailment caused by a friction bearing or a roller bearing?
  by NYCRRson
1943 derailment at PRR Frankfort Junction was before roller bearings;

https://web.archive.org/web/20150518093 ... 2F2726.pdf

The Mechanical Forces at PRR agreed that the axle journal was overheated and failed, but could not find an explanation why/how the journal became overheated.

Numerous trains traveling in the opposite direction and station personnel along the route did not observe "any trouble" as the train passed. The overheated journal seemed to "suddenly" appear after the train passed through North Philadelphia.
  by BR&P
NYCRRson wrote:1943 derailment at PRR Frankfort Junction was before roller bearings;
No, it was not.
  by NYCRRson
No, it was not.
In general during 1943 roller bearings where not in widespread use. The Frankfort Junction wreck was caused when a plain "solid" bearing / axle journal failed.

Yes some locomotives had roller bearings at that time and I would assume a few limited number of passenger and perhaps freight cars had roller bearings.

I restored an 1920 built Plymouth Locomotive (Model BL-2, 7 ton, gasoline engine, friction and chain drive, standard gauge). It had Hyatt Roller bearings on the axles. No reason to believe they where not the original bearings. Funny thing is the rollers where actually "wound" from square metal bars (about 1/2" square). The rollers where heat treated and quite well preserved. They look like a spring wound from square "wire" with very little spacing between the square bars (about 1/8").

So there was at least one class of locomotive built as early as 1919 (first production of that model) with roller bearings. But, roller bearings where not in widespread use in 1943.
Last edited by NYCRRson on Thu Mar 02, 2023 9:25 pm, edited 3 times in total.