Why do train wheels screech?

Question

I have just moved near to Victoria Station in London and have no real problem with the noise from the trains, but I am curious why some train wheels screech and some don't?

Answer 1

i think it is brake dust clogging the brakes...

Answer 2

usually on curves, but if the track is out of alignment, and forces the wheels sideways off of the course that they were going in, it will squeal.  This happens with the flange on the wheel, and I believe it happens with the part of the wheel that makes contact with the top of the rail when it is forced sideways.

Sometimes there is something at switches that are made to keep the wheels from crawling over the frog and derailing that the field side of the wheel makes contact with and will squeal.

Answer 3

Simply enough, they screech in curves and on straight track because the flange on the inside of the wheel contacts the "ball" of the rail and due to the degree of the curve being tight and the gage of the rail being narrower in some places than others.

Answer 4

The screeching is caused by the lip on the inside of the train wheel rubbing on the inside of the rails.  It's most common on curved sections of track and tends to ebb and flow as the weight of the train shifts from side-to-side as it negotiates the curve.

Answer 5

That would suck hearing trains all d**n day and night.

Answer 6

cause they're having fun!!!!!!!!!!!!!!!

Answer 7

Overcoming Friction!

Answer 8

METAL ON METAL

Answer 9

No one here has mentioned that a train has no equivalent to a deferential on a car. Trains have solid axles meaning that when it travels round a curve one of the wheels has to slip a bit, it is this slipping combined with the weight of the train that produces the noise

Answer 10

One factor in the amount of squeal is the distance between the wheels on the bogies. The Pacers used in the North of England, South Wales and the Bristol area are worst, as they only have 4 wheels per coach (instead of 8 on most trains)

Answer 11

I think its because they want everyone to know the train is there...lol

but it could be b/c the wheels are old and rusty and the brake might not be very good.

Answer 12

friction between metal wheel & metal rails cause both to vibrate a high frequency producing that high pitch screech.

Answer 13

maybe some have been recently greased and some havn't?

ultimately any metal on metal will make some sound.

Answer 14

As bostonian says it is caused by the flanges on the train wheels touching the rails on sharp bends. Normally the conical shape of the tyre profile keeps the wheels centred on the rails and the flanges should not touch. On some bends an arrangement is made to grease the rails to reduce tyre wear. The ones which screech probably have worn tyres due for re turning

Answer 15

Im a tube driver, and I have no idea lol. I think it could possibly have something to do with the curves, and the flange on the wheel touching the sides of the rails as it goes round (flange being the horizontal bit that goes down on the edge of the wheel itself)

Answer 16

Well why some sceech and why some don't, i'm not intirely sure but I've been to that station once before... I don't live in England but I've seen it and from what I remember there were trains that did and didn't screech as they came in... I think the speed, the way the track is layed out and metel on metel have something to do with it. Some trains may start slowing down before others and therefore when the train comes to a complete stop there is less or no noise coming from the wheels. It may also depend on the break system.. the new the breaks the better they'll work... so I think that the reason some do and some don't is because of the breaks and how soon the train comes to a stop... if it starts slowing down way before then there probably wont be as much of a screeching noise when it stops... but really this is all based on logic and from seeing trains stops and I remember helping my dad fix the breaks on our old van.. whenever we came to stop and he'd slow down real fast the breaks would screech loudly but when he would start to slow down way before there would be no or very little screeching... so yea this is all kinda a guess.. so I hope this helps in some way.. just not sure if it's right

Answer 17

more often u hear those sounds on the curves. this because of the wheels rolling on the track changing their direction according to the track. when load is heavy the scrach between track and  wheel is very tough another common sound arise when train comes is caused because of joins in the tracks hit with wheel and a sound CHAADAK.. CHAADAK is made.

Answer 18

The reason train wheels screech is down to vibration, have you ever heard your car brakes( if you own one), the metal vibrates

at a very high rate under load this  frequency translates to noise,

and thus the result is an annoying screech.

Hope this helps.

Answer 19

Its called flange squeal.

Bostonian and David P are dead on.

The flange (lip) on the inside of the wheel comes in contact with the rail as the flange keeps the wheel on the track on a curve or switch.. Metal on metal contact = resistance and voila; flange squeal.

Answer 20

friction

Answer 21

It's metal rubbing against metal...