wheel defects

Early this morning around 2:00 AM, I witnessed a train passing by that had sparks flying from one of its wheels. In fact, it looked like the entire wheel was glowing. It was on a tank car near the end of the train. Is this whats called a hotbox? The train passed a defect detector about 10 minutes after I saw it, but it detected no defects. Just wondering how dangerous this is...

A few weeks ago I saw something else that made me a little uneasy. The train was going about 50 mph, and about 30 cars back, a boxcar was "wobbling" more than I have ever seen a car do. I couldn't tell because of the speed, but it looked like one of the wheels was wobbling back and forth, as if it were warped. What causes this?

Nope, that's not a "hot-box", that's more than likely a stuck brake. A hot-box is an overheated wheal bearing. Named for the old style, plain friction bearings, that were encased inside of a journal box, these are not usually visible nowadays, unless the seals are burning. Hot wheels are quite common, due to sticking brakes , bent brake rigging, partially applied handbrakes, retainers improperly positioned, etc. Stuck brakes are common, due to a release of an application, without allowing sufficient time for that application to propagate throughout the train (thanks, LCJ ), or releasing the brakes without reducing trainline sufficiently, to effect a release, on rear portions of train, due to brake pipe gradient. (LCJ, again ) If enough wheels were hot, in a row, the detector would not recognize a difference, between the wheelsets, or the brakes could have released, by the time the detector was passed.

That "wobbling" boxcar is more difficult to understand. It could have been unevenly loaded, had worn centercups, had missing shims from truck bearings, narrow gauge on a wheelset, or the truck could have been experiencing high speed hunting, which although rare, does occur. Noting these things, and realizing they contribute to derailments, is good reason to stay far away from moving trains. A train at speed will throw cars hundreds of feet, out of a train, when things go wrong. Be sure to have that fun, from a safe and legal distance. Regards

Expanding a little more on the excellent comments that GOLDEN-ARM made, be very careful not to stand anywhere near the trailing side of a diamond or a turnout. If there is anything about to become detached from the brake rigging or suspension of a locomotive or a car in the train, it is most likely to be thrown when the wheels cross these track fixtures, and will usually be tossed in the direction of the train's movement, to the trailing side of the diamond or turnout. The local impact loads at the wheels when crossing a diamond at 60 MPH can be close to 20 times the force of gravity.

A few weeks ago I saw something else that made me a little uneasy. The train was going about 50 mph, and about 30 cars back, a boxcar was "wobbling" more than I have ever seen a car do. I couldn't tell because of the speed, but it looked like one of the wheels was wobbling back and forth, as if it were warped. What causes this?

I don't think the wheels would be warped, but I've seen boxcars rock back and forth a lot (although not enough to cause alarm). From what I've seen, it happens when they are empty, and the natural rocking frequency coincides with the frequency of the track joints ("resonance"). I've never seen loaded cars to this, probably because the natural rocking frequency is different and because they are more "firmly planted" with the weight of the load.

Yo Trainiac,

Sounds right. Once loaded and the center of gravity has dropped, the oscillation would cease.

foggy83 wrote:A few weeks ago I saw something else that made me a little uneasy. The train was going about 50 mph, and about 30 cars back, a boxcar was "wobbling" more than I have ever seen a car do. I couldn't tell because of the speed, but it looked like one of the wheels was wobbling back and forth, as if it were warped. What causes this?

Sounds like a "hunting" truck. The truck will oscillate in a horizontal plane ("wobble") with a frequency of once or twice a second or so.

I observe hunting trucks occasionally - along both jointed and continuously welded track. Seems more common on empty cars (spline cars, auto racks, etc) and at high speeds. Also seems more common toward the rear than toward the head end of a train. Have even seen sparks come from the wheel flanges at the peak of each oscillation of a hunting truck.

Good reason indeed to allow plenty of space between yourself and a moving train! ...FB

Hi,

Possible, but you would hear a hunting truck. This is where I first heard the term Swayle. It refers to the squeal of the wheels as a hunting truck bounced from one side of the rail to the opposing side of the other rail.

pennsy wrote:Possible, but you would hear a hunting truck.

Indeed Alan! I should have mentioned you usually hear a periodic squeal from a hunting truck also. ...FB

Slightly off-topic, I had a wheel break, at MP 12, a couple of weeks ago. 49 MPH, and through several facing and trailing point switches. Made it all the way into the yard, and was recrewed, before defect was noticed, during the roll-by, on the outbound train, Car didn't derail, but did break the rail, every 112 inches, for quite a distance. As a reward, for not derailing, the MOW guys gave me the pie shaped piece of wheel, that broke off. Cracks all the way to the axle, were visible on the wheelset, seen after it was removed from the car. I bet THAT was something to see, pounding it's way down the main, at nearly 50 MPH!!! The wheel piece I have, is over 150 pounds, in weight. Will post a few pix, shortly. Regards

Hi Golden,

Must have been quite a sight, and feeling. The title of that movie, "God is my co-pilot" was obviously true.

Some years ago, BNSF was running a long freight to Los Angeles. In San Dimas the last wheelset on the lead diesel snapped in half, dragging the traction motor, and tearing up the track like you never saw. The train stopped, and the lead engine was cut off and shoved into a siding. Additional track damage and really messed up electric/ electronic signals transmitted through the rails. After some time, hours, two trucks from Barstow showed up, and repairs were made to the tracks and wiring. The broken axle was removed, a non-powered axle was put in for transportation to Barstow for complete repairs. The train continued on with one engine less. The damaged diesel was returned to Barstow under its own power, on four axles and three traction motors. As we watched, comfortably from the seat of my trusty Schwinn, a hot dog truck with soft drinks pulled up and did a land office business. Good hot dogs.