Tube trains primarily brake using dynamic braking, a method that utilizes the train's electric motors to slow it down.
Understanding Train Braking
Trains require powerful and reliable braking systems to control their speed and come to a safe stop. While various methods exist, the specific type often depends on the train's power source and design.
Dynamic Braking Explained
Based on the reference, dynamic braking is a key method, particularly for electric and Diesel electric locomotives. It works by employing the train's electric motors in a reversed function.
- How it works: Instead of using mechanical friction, dynamic braking converts the motor into a generator.
- Process: As the wheels turn the motor (acting as a generator), electrical energy is produced. This energy can then be dissipated as heat or returned to the power supply (regenerative braking).
- Benefit: This process creates a braking force that slows the train down without relying on physical brake pads rubbing against the wheels or track.
The reference explicitly states: "Especially in electric and Diesel electric locomotives Dynamic braking works by using the Train's electric motors in Reverse. Instead of using mechanical friction to slow down the train Dynamic"
Since tube trains are electric, dynamic braking is a highly effective and common method they employ.
Contrasting with Mechanical Friction Braking
The reference highlights dynamic braking as an alternative to "mechanical friction". Mechanical friction braking involves physical components, like brake pads or shoes, pressing against the wheels or brake discs attached to the axle to create friction and slow the train. While many trains, including tube trains, may also have friction brakes (often air brakes that activate brake shoes or discs) as a backup or for final stopping at low speeds, dynamic braking handles the majority of the braking effort from higher speeds, reducing wear on mechanical components.
Why Dynamic Braking is Suitable for Tube Trains
- Energy Efficiency: Regenerative braking (a form of dynamic braking) can return energy to the power grid, which is beneficial in a system like the underground network.
- Reduced Wear: Less reliance on friction brakes means less wear and tear on brake pads, wheels, and tracks, leading to lower maintenance costs and noise.
- Smooth Braking: Dynamic braking can provide smooth deceleration.
In essence, tube trains leverage the power of their electric motors, running them in reverse, to perform the crucial task of braking efficiently and effectively, as described by the principle of dynamic braking.
