When observing a moving train, you might notice something unusual on the axle—four wheels, instead of the expected two. While the two larger hubs are in contact with the rails, the two smaller hubs in the middle seem to serve no purpose. However, these seemingly redundant hubs are actually crucial to the train's braking system. They are the brake discs, an essential component for ensuring safe and efficient train operation.

Types of Train Brakes

Train braking systems come in three main types: disc brakes, block brakes, and track brakes. Each method is applied to different parts of the train—axles, wheels, and rails, respectively.

Disc Brakes

Disc brakes, as seen in the initial observation, are installed on the train’s axle. This system is similar to the braking mechanism found in automobiles. Brake pads are mounted on the axle, and when the brakes are applied, two calipers press tightly against the sides of the brake disc. The friction generated by this contact converts kinetic energy into heat, effectively slowing down and stopping the train. The primary benefits of disc brakes include smooth braking, low noise, and efficient heat dissipation, making them the preferred choice for high-speed trains traveling at speeds of up to 120 km/h.

Block Brakes

Block brakes operate similarly to the old-fashioned bicycle braking system. Here, the brake pads press against one side of the wheel. When the brakes are engaged, the pads gradually press against the wheel's surface, using the resulting friction to bring the train to a halt. However, this method generates high temperatures, reaching up to 400-500 degrees Celsius, which can cause significant wear on the wheels. This not only shortens the lifespan of the wheels but also introduces potential safety risks.

Track Brakes

Track brakes, while effective, come with their own set of challenges. Resembling a row of teeth hanging beneath the train, these brakes are lowered to press against the rails when braking is required. The friction generated by this contact can cause considerable damage to the rails. The sparks produced during this process can be mistaken for special effects, highlighting the intense friction at play.

Conclusion

When comparing these three braking methods, disc brakes stand out as the most commonly used and the safest option. Their smooth operation, low noise, and efficient heat management make them ideal for modern trains.