Train brake shoes are typically made of cast iron, often with a friction material bonded to the surface. This friction material is designed to create friction when pressed against the wheel, slowing the train down.
Here's a breakdown of the materials used:
Cast Iron
- Base Material: Cast iron provides a solid and durable base for the brake shoe.
- Advantages:
- Strength: Cast iron is strong and can withstand the high temperatures and pressures generated during braking.
- Heat Dissipation: It effectively dissipates heat, preventing overheating and damage to the brake system.
- Cost-Effectiveness: Cast iron is relatively inexpensive, making it a practical choice for brake shoe construction.
Friction Material
- Purpose: The friction material, bonded to the cast iron base, is the primary component responsible for generating braking force.
- Common Materials:
- Asbestos: While asbestos was previously used, its use has been largely phased out due to health concerns.
- Non-Asbestos Organic (NAO) Materials: These materials are a popular alternative to asbestos. They are made from a combination of organic fibers, resins, and fillers.
- Semi-Metallic Materials: These materials contain metal particles mixed with resins and fillers, providing high friction and wear resistance.
- Ceramic Materials: Ceramic materials offer excellent heat resistance and low wear rates, making them suitable for high-performance applications.
Other Materials
- Steel: Steel is sometimes used for specific components of the brake shoe, such as the backing plate.
- Copper: Copper may be used in small amounts in friction materials to improve conductivity and heat dissipation.
The specific materials used in train brake shoes vary depending on the type of train, its operating environment, and the desired performance characteristics.
