We have travelled thousands of kilometers in trains, but we haven’t given a thought about how do trains turn during a curved path ? Both the wheels are connected through an axle & obviously are of same diameter. But,when a train takes turn, the outer wheel has to cover more distance than the inner one…! How is this possible ? How can the outer wheel cover more distance than the inner one even when both the wheels have same diameter ??? 🙁

## How do trains turn –

The solution is simple & elegant.

Both the wheels are a bit **flanged **OR** conicle**. The part having greater diameter of the frustum of the conical wheels is inward while of lesser diameter are outwards the track.

Now whenever a trains travel on a curved track, **the wheels get slide away in either of the direction**.

The following happens while taking a turn –

- Suppose the train is taking a left turn(as in the above picture). Which means the wheels will slide to the right(→) side, obviously due to
**centrifugal force**. - The outward force-centrifugal force results in increment of diameter of right wheel(↑) & decrement of left wheel(↓) during the turn(the black line on wheels in the above image).
- The right wheel covers more distance than the left wheel since the right one has greater diameter than the left one & hence the problem gets solved ! 🙂

Also it solves one more major problem. Whenever there is a bump on tracks, the wheels suddenly slide even when travelling on a straight track & there is a great danger of being derailed, so the same design helps to stabilize the train & to run smoother.

Here is a video which will help you to understand it better.

In engineering,

The most simple designs are considered as the best solutions !

So besides the working, what we also learn is that – It isn’t necessary every time to make complex machines & design complex mechanisms, **all it takes is a simple design** of the thing what we already have.

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