Author: Claire Publish Time: 2024-03-05 Origin: www.train-wheels.com
The "wheel" under the train vehicle is called a bogie in technical terms. Each bogie usually has 2 pairs of wheels, and there are also 3 pairs. It is generally only used on some locomotives. Each carriage generally has two bogies, at the front and rear of the carriage.
The picture below shows the train bogie. The bogie is equivalent to a 4-wheel car.
Why use a train bogie instead of wheels like a regular car? This is due to the need to bear weight and turn.
Early trains used front and rear axles similar to cars. Later, as the weight and length of the train continued to increase, the design of the front and rear axles could no longer meet the needs. However, if the axles were added, it would bring inconvenience to turning.
Trains use locomotives to pull carriages (except EMUs), so the principle of changing directions is different from that of cars. A car relies on the driver to control the steering wheel. The train has no steering wheel, and parts other than the locomotive are not even powered. The direction of progress is fixed on the track. In other words, the train's "wheels" need to be able to adjust their direction on their own.
Therefore, the train is designed with such a thing as a bogie. The principle is very simple. When the train needs to turn, the bogie needs to rotate around the axis of rotation and change direction as the direction of the track changes. This ensures that the giant carriage can easily change directions. You will understand when you look at the picture below.
In this way, it is easy to understand why two or more pairs of rail wheels are needed to form a bogie, because if there is only one pair of wheels, the wheels may swing and cause trouble in driving, as shown in the figure below. (The bogies of EMU trains and ordinary locomotives also need to be driven by motors)
The railway bogie also has a certain shock-absorbing effect, which improves the stability of the vehicle and the comfort of the vehicle's ride.
