Özet:

Railway vehicle brake systems provides safely stopping, slowing and its movement at the appropriate speed. Mechanical braking is commonly performed by the effect of friction, and the use of brake discs is the only reliable option when railway vehicle is designed for high speed. The dimensions and weight of the brake discs, the area under the chassis, the service speed of the train, etc. varies as it is designed according to the parameters. The weight can be reduced by up to half, when different materials are used. During braking, mechanical energy is converted into heat. The air flowing between the ventilation vanes, which can be designed in various shapes and sizes, provides effective convective cooling in the disc. Locally overheated areas cause structural changes in the brake disc material, thermal crack formation and other damage. If these damages are not controlled and progress and turn into deep cracks, the disc becomes unusable over time. Lamellar, vermicular or spheroidal graphite cast iron is commonly and traditionally used in the manufacture of railway vehicle brake discs. Also cast irons with special compositions, as well as casting and forging steel. Various alloying elements can be added to the composition to increase the fracture toughness and wear resistance of steels to be used as brake disc material. There is also the use of composite materials especially aluminium or ceramic matrix composites thus, a train brake disc desired property and very light can be produced. In this study, information is given about brake disc structure and cooling vanes, heat generation and transfer in braking, heat gradients and problems in hot regions, thermal cracks, materials used and can be used in brake discs.

Anahtar Kelimeler: