jarrupyörä

A jarrupyörä, often translated as brake disc or rotor, is a component of a disc brake system. It is a circular metal plate that rotates with the wheel of a vehicle. When the brakes are applied, brake pads clamp onto the surfaces of the jarrupyörä, creating friction. This friction converts the kinetic energy of the vehicle into heat, which slows down and eventually stops the vehicle.

Jarrupyörät are typically made from cast iron, steel, or sometimes more exotic materials like carbon-ceramic composites for high-performance applications. The material choice influences the brake's performance, durability, and heat dissipation capabilities. Cast iron is common due to its cost-effectiveness and good friction properties, while carbon-ceramic offers superior heat resistance and lighter weight, but at a significantly higher cost.

The design of a jarrupyörä can vary. Solid discs are simpler and used in many lighter vehicles. Vented discs, common on heavier vehicles or for higher performance, have internal vanes or passages that help to channel air through the disc. This aids in cooling the disc, preventing brake fade, which is a reduction in braking effectiveness due to overheating. Perforated or slotted discs also exist, designed to improve heat dissipation and help clear away brake pad debris. Regular inspection and maintenance of the jarrupyörä are crucial for ensuring effective braking performance and vehicle safety.