No one gives much thought about the train wheels because they look normal, right? Well, looks can be deceiving. A lot of thought went into designing the train wheels. The wheels are fixed on the axle in unison. This means if the left wheel rotates by X degrees then even the right wheel rotates by the same. The complication arises when the train is making a turn. You can’t expect it to travel in a straight line always, can you? While the train is traversing a curve, one wheel travels more distance than the other. To overcome this challenge, the wheels instead of being in a cylindrical shape are made in a conical shape. The smaller surface area of the wheel faces outwards, and the larger surface area faces inwards of the axle.
Why choose this way?
When the train makes a right turn, the entire weight of the train shifts to the opposite side, i.e. the left side in this case. This means the left wheel must cover more distance than the right one.
A typical railway wheel is designed such that little edges called flanges are little outwards of the wheel. These little things are the sole reason why the train never slips from the track. Beneath the two rails, you may often notice the wooden planks. These planks maintain the same distance between the two rails, reduce vibration and spread the load from the rail to the ground.
Notice how the points of contact of the wheel and the track are the same for both wheels. It is because of this the train is traveling in a straight line.
The points of contact change significantly when the train is making a turn. You can spot the difference below.
Now you know how the train wheels function optimally.