Chloroprene rubber (CR): The first generation of belts were not subjected to high operating loads or large thermal loads at an operating temperature of 80 °C to 90 °C. These belts had a short service life because the rubber quickly became brittle. This was accelerated when it came into contact with any escaping engine oil.
Highly saturated nitrile rubber (HSN): Provides improved resistance to stresses and operating temperatures up to 110 °C.
Hydrogenated acrylonitrile butadiene rubber (HNBR): Offers improved resistance at load and working temperatures up to 110 °C. Used in the latest generation of timing belts, e.g. also for febi timing belts. HNBR is characterised by ideal temperature resistance, low friction, and noise development during operation. It also has an increased service life and complies with EURO 5 and EURO 6 emission standards for timing and combustion values.