How does a train stay on the train tracks?

Question

How does a train stay on the train tracks?

Answer 1

Look closely at the wheels.  They have a lip on the back that makes them grip the inside of the track.  Since they're on both sides, it stays most of the time.

Breaks in the track, large objects (no a coin isn't large enough) can cause a train to de-rail.  If a train goes too fast around a corner it can de-rail as well, but that usually takes super speeds.

Answer 2

Dirtydog, Tom-SJ and uther aur are right on the money.  The flanges and wheel taper allow the trucks to follow the rail and negotiate curves.  But it is gravity itself that ensures the equipment stays on the rail, instead of climbing over the top.

Uther aur points out that in curves at elevated speed a train will derail, and he is absolutely correct.  And here is why;

There is a simple formula to determine how or if a car or locomotive will stay on the tracks.  It is known as "L over V", or L/V.

What this means is, as long as vertical force (provided by gravity) is greater than lateral force (centrifugal force) the equipment will stay on the rail.  If lateral force becomes greater than vertical force, whether due to excessive speed or other factors, the wheel flanges will "climb the rail" and derail on the high side (outside) of the curve.  As was pointed out, the flange on the wheel is quite small in relation to the wheel itself, and doesn't have to go very far to climb the rail.

Answer 3

Tom SJ has given you a great answer... a note about that flange.... it does keep the wheel  on the track but if it gets too high or thin  due to wheel wear, then it can do the opposite....thats why wheels are checked often...We checked about 360 wheels during my shift today...If I find a flange thats too high or one thats too thin I send the locomotive to the wheel truing machine...

Answer 4

Railroad wheels have a flange about 1" high on the inside edge of each wheel.  The pair of flanges keeps the axles centered on the pair of tracks, so they don't run off track.

In addition, railroad wheels have a slightly tapered profile - a smaller diameter on the outside, a larger diameter on the inside of the wheel - to keep each wheel centered over the rail.  

The taper also helps each axle turn smoothly on a curved section of track.  Because a railroad axle solidly connects the left and right wheels, when making a turn, the inside wheel on an axle needs to turn a smaller distance than the outside wheel.  The taper provides this capability.   (RR wheels & axles are unlike automobile differentials, which allow the left and right drive wheels to turn independently.)

Answer 5

The outside of the wheel have an edge on it so it not come off the track. I try to find you a picture.

http://www.istockphoto.com/file_thumbvie...

Answer 6

The train stays on the track because it wants to.

Answer 7

All of them r correct but the thing they r lacking is that the running of the train,i.e., the rotation of the wheel also creates a magnetic effect upto a certain extent which does not allow the wheel to come out of the track which in turn prevents the train to topple.

Another point is that various countries use different type of technologies depending upon the weather conditions. For instance Japan uses the technology of magnetic induction to run the train.

Answer 8

The wheels have inboard flanges so that they cannot come off the tracks unless the flanges rise high enough to allow it. The flanges are about six inches to eight inches high.