Hot Boxes

[Anonymous]

Flat Spots: There are detectors made just for that purpose. Strain gauges are tact welded to the web of the rails. The sensing equipment will trigger after a certain threshold has been crossed when the wheel's flat spot impacts the head of the rail. The ones I've seen measure this in "x" amount of kilograms of impact force. Then, the equipment would automatically send the data via a modem that would print out the data. At some point, the car would be set off for repair. We've had rail break from the force of a really bad flat wheel on a freight train recently. Broken on the same track in 2 different locations along the line. I guess the bitter cold conditions outside didn't help matters.

Hot Box Detectors have been used for years on some railroads in the "reverse sense" of detection - cold wheels. Since the HBD can be triggered by a "differential alarm" setting (how many degrees hotter is one wheel than the other is on the same axle), if one wheel was "cooler" than the other, because of the lack of heat being generated due to a brake not working properly.

Hot Wheel Detectors are optional scanners a railroad can purchase that are mounted on small poles that look for sticking brakes. The HBD isn't really intended by design to detect a stuck brake, but, it can "see" those at times. Especially, with brake shoe particles zooming across the scanning field of the detector's optics. When running calibration tests, the HBD can detect your body heat should you cross in front of the scanners. It won't tell your temperature (you need a "Fever Detector" for that), but, you can cause a slight deflection. Optical focal points come in to play with the detectors, so, you're really not at the right point to be "seen" properly.

The HBD basically makes a comparison between the journal's radiated infra-red energy and the ambient outdoor temperature. When I'm looking over HBD data and see temperatures such as: 17º, 34º, 49º, etc, that's telling me that those journals were actually that many degrees above what the outside temperature was at the time the train was passing over the HBD.

[Anonymous]

Most BNSF TWD's will now not talk unless there is a defect. This is good as it cuts out on unnessary chatter and this helps when your train is switching on the mainline switching. TWD's are not fail safe and can trigger false alarms. Sometimes this can be a op test by some sob waiting in the weeds to see if the proper procedures are followed. I heard of a crew once that sat stop for well over an hour waiting for traffic. After getting on the move, they passed a TWD just five miles from where they took off. The TWD nailed not one but two cars on the train! This may have possibly been an op test. The crew setout the cars at the next siding just to make a point. Some op tests are on TWD's and sometimes this can backfire on the rr if a crew is creative and wants to follow everything to the exact point.

[tree68]

Haven't seen the original HBD mentioned here - the conductor's nose (in the caboose). Hot boxes had a rather distinctive smell, IIRC. Seems like I read somewhere once that roller bearing cars were (at one time) being equipped with something that would either smoke or smell bad if they overheated, allowing those in the caboose to pick up on the problem. Obviously not a solution today.