Why do train wheels make noises..?

Question

I mean like.. I was on a walk, and I had to stop, and wait for a train. I noticed there was a louder car coming, I looked at the wheels. Thats where it was coming from, but then as the one car went away so did the noise, then I heard it again, from another car.

is there some like flat side on the wheels? lol

Answer 1

its the metal wheels hitting the joints in the rail sections

Answer 2

Flat spots.

Flat spots are usually created when an empty car is moved with the hand brake still applied.  Loads, being much heavier, are less likely to slide a wheel flat.  If flat spots are excessive, if I remember correctly, two inches or more in length, the car must be 'set out' and not moved until inspected and the problem corrected by car department personnel.

Car department personnel address the problem in the field in one of two ways.  Either the wheel / axle assembly is changed out, or (usually on locomotives) welders come in and built up a 'patch' of sorts to reduce the length of the flat spot, so it can be moved to a service facility.  This usually puts a significant speed restriction on the locomotive.

Once at a running service facility, the engine is put on a 'wheel machine', sometimes referred to as the 'peeler', which brings the wheel back into round.  But there is only so much that the wheel can be pared on what is essentially a giant lathe.  Keep in mind, as the diameter of the wheel is changed, it is now smaller than the rest of the wheels, and at some point the wheel involved and the axle it is mounted on are subject to 'wheel slip' problems, reducing the pulling capacity of the locomotive.

An engineer who 'flats' a wheel can be subject to discipline.  Engineers who take charge of a locomotive consist that already has a flat spot on it inform the proper authorities immediately, lest they be charged with creating the flat spot.

Another problem when wheels are slid flat is that there is a lot of friction that creates the flat spot, but it also creates a huge amount of heat at the same spot.  This can cause 'thermal cracks' which are undetectable to the human eye, that can cause a broken wheel, and a derailment is always the end result.

Sometimes there are multiple flats spots on a wheel, and in this instance you'll not hear the thump, thump, thump of a flat spot but more of a general roar.  It is usually the case that when one wheel is flatted, the other wheels on the truck are flatted as well.

Answer 3

If it was a thumping sound that was recurring form one car to the next it was likely a gap between the rails, where they are bolted together. If it was only one car and followed it along it would have been a small "flat spot" on a wheel caused form sliding. The screeching and squeeling is usually caused by the flange of the wheel rubbing against the inside of the rail.

Answer 4

I think jesteele1948 has given the best answer. In addition to wheel wear causing noises, joints in the rail can thump and slap. Bolted joints tend to sink over time and will make quite a noise if they aren't tamped up. Screeching also comes from the wheels' flanges rubbing the inside of the rail.

Answer 5

flat spots, as defined by the AAR and the FRA are almost always caused by a hand brake left on usually on an empty or lightly loaded car.  a asingle flat spot is FRA condemnable at 2 1/2"  in length. ( i'm not 100% sure about this measurement..don't have the book in front of me..doesn't really happen that often in the intermodal world)  two or more ADJOINING flats spots are condemnable at 2" in length.

they do make a heck of a thumping or banging sound and can cause a lot of stress to all related truck parts.  brake rigging, air brake piping etc.

squeaky or squeeling wheels are usually caused by brake shoes against the tread at lower speeds or at any time by the flange of the wheel contacting the inside vertical face of the rail head most often when going through a curve but certainly not always.  newer wheel sets will do this a lot until worn in a bit.

just plain old noisy, rumbling wheels are usually the result of the tread shelling in spots.  sometimes in just one spot, sometimes in a lot of spots around the circumference of the wheel.  those are caused by smaller brief episodes of the wheel sliding which builds a lot of localized heat at the wheel tread/rail head contact point.  the metal actually changes to a substance called martensite.  martensite is an extremely hard and extremely brittle metal.  these areas will break out and cause small;  holes, if you will,  that are shallow but can cause a heck of a racket.  They are condemnable if around the circumference of a quarter with no 'islands' within the shelled area.  the feds differ from the AAR in the condemnable dimensions in this case.  the feds say a wheel is condemnable for this type of defect no matter how wide the shelled spot is but it has to be 2'' in length or more with no restriction on the width.  it could be 1/8'' wide but 2 " in length and be a condemnable wheel.

built up tread is another cause of noise in rairoad wheel sets.  this is usually caused by the hand brake being left on.  the metal that is melted/rubbed off is deposited on the wheel tread just behind the slid flat spot.  sometimes in can be left all around the circumference of the wheel.  in severe cases it can be bad enough to actually lift the wheel off the rail.  in some very extreme cases it can build up to the point at which it accumulates under the bottom edge of the brake shoe and will stop the wheel set from rotating completely.  

some cars; ie, stack cars , spine cars and covered hoppers have air brake valves incorporated into the air brake system that will decrease air volume into the brake cylinder in an 'empty car'  condition.  a heavy brake application on an empty car can cause intermitant wheel sliding resulting in small super heated areas on the tread which will eventually end up as a shelled tread.

Answer 6

It's heavy!

Answer 7

It is just what you said. If someone was a little long on using the brakes they develop flat spots. Up to a certain point this is OK thats why you hear what you did. But if it becomes to much then the railroad maint folks have to turn the wheels on a big lathe and say bad things about the engineer under their breath.

Answer 8

There can be flat or worn spots on the contact surface of a wheel.  There can also be an out-of-round condition that can be heard with varying contact with the brake shoes.  

The flat or worn spots are usually from some incident(s) in the past when very hard braking was required to stop the train, and a wheel was fully braked (not rotating) and the car it was on was dragged by the rest of the train.  The flat spot might be small, but the weight on the wheel is so great that a lot of thumping is generated when simply turning.  

When the flat spot was created, the sliding friction was generated by the rail, but the rail is harder steel, so the wheel shows most of the wearing effect.  The brake shoe is also hard, but when it is applied, it can be applied with so much force that the wheel does not slip past the brake shoe.

Answer 9

the brakes rubbing on the wheels

trains have to brake when coming to a crossing

Answer 10

Yes, yes there is.

Answer 11

If you want to get a job that deals with trains, which is what you said in a previous question you asked, then you'd better know some of this stuff.

Answer 12

all things that move make noise

trains are big there for lots of noise

Answer 13

Depends on the type of noise you heard. A squealing noise may be the bearings a little under lubricated. A rhythmic clunking sound may be a flat spot on the wheel.

Answer 14

Most likely was the load on the individual car. The unloaded ones don't stress the tracks or axles. A heavy load will do both, and be noisy as a result.