Occasionally, I hear a banging from a freight car as it passes. I assume this is a flat wheel or wheel bearing problem. What gets me is, this is LOUD, how can this not be damaging to the track/car/load? Assuming this is a flat wheel, how do they get this way? What is the railroad’s policy towards repairing those?
Hello Ed.
The ‘banging’ you hear could be from ‘slack-action’ alright…but when slack runs in, it usually does’nt happen again for several second’s unless the Hog-head is a Moron at the control’s, and can’t control the said slack in his train. Going down-grade, he would have the slack ‘bunched’, and keep it that way for some distance until he probably took the Engines out of ‘Dynamic’ and into ‘Power’. As far as sound levels of Slack vs. Flat-spot’s, the slack would be much louder, especially if the Hogger used to much ‘air’, or ‘dynamic’ in to much of a hurry to ‘bunch-them-up’ and did’nt let the car’s come-in gradually.
As you probably know, ‘flat-spot’s’ and ‘shell-out’s’ must be addressed quickly, because car’s in the train with such problem’s can very easily break the rail…Take Care…Bruce
Your right it is a Flat spot on the wheel. You have to realize that most likely the only way to know there is a Flat spot is when they do a roll bye and when the car comes up for its inspection. The Railroads hate to take a car out service because it means lost revenue. And the crew is inside the locomotive and Most likely cant hear it to report it. Help this helps you.
I am not sure what the policy is on the repair, but most often the flat spot develops from being drug a distance with the brakes locked up.
Most crews carry a flat spot gauge ( one of which I have thanks to a passing UPS crew) which they use to measure flat spots on a wheel flange. This is usually caused by locking up the wheels on braking. When it reaches a certain point they will bad order the car and take it out of service.
Thanks guys, pretty much what I figured. However, how does a wheel get locked up? I know that trains have no ABS, but does an empty car lock up a wheel if the rest of the train is loaded? That seems too common, many trains run with empties and loads. Perhaps maladjusted brakes? That seems most likely. I think that the shocks caused by the flat spot would cause stress on the bearings, trucks, welds, and cargo. I think that repairing a flat wheel would be more cost-effective in the long run. It might even effect fuel economy, to some small degree. I guess load damage doesn’t count on a coal hopper. Heck with it.
All you have to do is watch a yard crew in action.They will set the hand brakes brakes on the last few cars and shove the cars into a track,avoiding a sometimes lenghty walk back to the head end.
Those flat spots also occur when a full service brake is applied to an empty car with loads in the train. Yard crews also put a car or two in a track with hand brakes applied and then kick cars on top of these cars to save time in the switching operation.
The gauge which was talked about earlier was measuring the thickness of the wheel flange not flat spots. If the wheel flange gets thin or “sharp” it might split a switch and cause a derailment.
The federal standards for flat spots mention a specific size (can’t remember what it is) for one flat spot, or two flat spots next to each other of a smaller size, beyond which the wheelset must be replaced.
I wouldn’t worry too much about damage to lading or the car. I’ve seen some cars reacting to an extremely large flat spot, but those were extreme cases, in a yard, en route to being repaired. I’ve also ridden in passenger cars with flat wheels, and the noise is the biggest annoyance; you don’t really feel it. Keep in mind that in most cases it’s only one wheel or a pair of wheels, out of eight, that’s flat at any given time.
Related observation from an old-timer: I hear a lot more flat wheels now than I did in my youth…could it be that the noise used to be masked by the now-rare clickety-clack of the wheels on rail joints?
The noise you heard was probably ‘flat spot’s’. How-ever, it could just as easily been a build-up of ‘slag’…caused by the literal melting of brake shoe material during brake application, and said material solidifying on the wheel. It could just as easily be a ‘shell-out’, where the casting of the wheel becomes compromised. A chunk of casting falls off leaving a hole on the surface of the wheel…usually about 2-3 inches in diameter, and about an eighth of an inch deep. If there are flat spot’s measuring 2.5 inches or longer…or if there are 2 flat-spot’s adjacent to one another measuring 2 or more inches on any one car, this is usually considered a ‘bad-order’ and the car must be ‘set-out’ at the nearest point if discovered en route. At an initial station… the car would be removed from the train.
What are the limits on a shell-out?
Hello Daniel…I have experienced several ‘shell-out’s’, and the rule of thumb for the B.N.S.F. Car shop that I occasionally deal with is…if there is a 1 inch in diameter ‘shell-out’, set-out, or leave the car at the initial terminal. The F.R.A. usually look’s at the length…usually a 2.5 inch in length occurance, similar to a flat-spot to meet the criteria. I’m sure that if ‘Gregg’ read’s this, he will in some way contradict me, but this is how we generally operate on a class A rail-road as opposed to a ‘short-line’…Good Luck…‘and keep it on the rail’…Bruce
Generally, brakes on a car do not lock up except during emergency braking or if the handbrake is set. The cars have what’s called an empty/load device on them which determines how hard to set the brakes in any given circumstance. On stack cars these devices are rather easy to spot, they are a little arm right above the trucks, when the brakes are set this arm descends to the truck frame and based on how far it has to go to get to the frame determines whether the car is empty or loaded (and to some degree how heavily loaded). This is all based on the spring compression. As to your question about damage to track, yes in the case of a heavy car with a bad flat spot it can damage or break the rail (particullarly in cold weather). And yes, it will eventually chew up the bearings if left unattended for too long. The truck frames themselves are incredibly strong, there is seldom a problem with them. On the UP, we now have several (I think there’s 10 of 'em so far) wheel impact detectors, which flag a car based on the impact on the track. They do this at track speed and then if any impacts are detected that particular car will be “tagged” for repair at the next location where 1000mile inspection is performed. If the impact is really severe a message is transmitted over the radio and the car has to be immediately set out. Interestingly, this device is also catching lot’s of engines (mostly due to dynamic braking or improper use of the engine brakes).
I always thought the banging sound was a result of slack comming out of the train. I hear this loud banging from miles away in Richmond, Va where coal is comming down grade from the West on the CSX tracks parallel to the James River.
Is the banging you hear from a flat spot comparable to the banging you hear from slack? I would also expect the banging from a flat spot to be very rythmic.
Just curious. - Ed
Hello Ed.
The ‘banging’ you hear could be from ‘slack-action’ alright…but when slack runs in, it usually does’nt happen again for several second’s unless the Hog-head is a Moron at the control’s, and can’t control the said slack in his train. Going down-grade, he would have the slack ‘bunched’, and keep it that way for some distance until he probably took the Engines out of ‘Dynamic’ and into ‘Power’. As far as sound levels of Slack vs. Flat-spot’s, the slack would be much louder, especially if the Hogger used to much ‘air’, or ‘dynamic’ in to much of a hurry to ‘bunch-them-up’ and did’nt let the car’s come-in gradually.
As you probably know, ‘flat-spot’s’ and ‘shell-out’s’ must be addressed quickly, because car’s in the train with such problem’s can very easily break the rail…Take Care…Bruce
the most common cause of flat spots is actually the car sitting for long periods of time loaded or just if its a heavy car. plus, i heard the wheel sets are sanded once then scrapped.
Flat spots and shelling damage can be ID’ed because they occur in a rythmic sequence each time the wheel revolves. Shocks from shelling are nearly as bad as from flat spots, but either can cause a broken wheel if the wheel gets hot enough.
The increase of flat spots on the road is a direct result of no cabeese. There is no one to roll the train by at every crew change.
Other "loud noises"come from stress release, almost always an empty. If it is an empty box car with doors open, the “box” superstructure will act as a loud speaker, and you could believe that the car is about to come apart. Usually happens at slower speeds. You will hear this sound only once per car, and usually on only one car.
I would describe the banging sound of wheel flatspots as most comparable to a metal bucket of bolts hitting the ground every second or a dozen times a second (depending how fast the train is moving).
Ok,
Wheels are machined, by axle set, even if only one wheel on a axle has a flat spot, to keep both wheels on any given axle the same diameter, if you only machined one, the truck the wheel set went on would yaw, or drag on the smaller wheel.
Would love to see one sanded, although my engineer can sand the brake shoe slag off the locomotive’s wheels with the sanders and a small brake application on the independent brake.
Any car can have it’s brake cranked down to the point it locks the wheels.
My helper can tie a hand brake on just about any car, loaded or empty, that will slide the wheel flat if you drag it.
Most flat spots occur because a yard crew dosnt do what they are supposed to do, tie a brake on the bumper car that wont lock the wheel.
Have yet to see a flat spot created by a car sitting still, unless in sat for few centuries, come on, the wheels are hard enough to take the pounding of several tons on crappy tracks, I doubt they would deform under the static weight of a loaded car.
If that happened, the all the cars in a SIT yard would have flat spots, they can sit there for months at a time.
They might get a rusty spot, but that would go away with the first brake application.
Emergency application of the brakes at track speed will give you flat spots, just depends on the circumstances as to how big.
The GCOR states the after an emergency brake application, the conductor must walk both side of the train, looking for wheels slid flat, and wheels that are derailred or damaged before the train can be moved.
2 to 2.5 inch flat spots are is the AAR interchange rule, above that, the wheel is condemened, and must be machined.
Two or more flat spots exceeding 2.5 inches on any wheel, the wheel is condemened and scrapped.
Lazy yard crews, and lazy carmen cause flat spots.
Yard crews do so by tieing one hand brake to the limit, and kicking cars against this single car
Ed…the sliding wheel sounding just as frying bacon, but I’ll bet it doesn’t smell like it…