Tandremmar

Tandremmar, in automotive terminology, refer to timing belts used in internal combustion engines to synchronize the rotation of the crankshaft and camshaft(s). The teeth on the belt engage with matching grooves on pulleys, ensuring that valves open and close at the correct times relative to piston position. Proper timing is essential for engine performance and prevents valve-to-piston interference in many engines.

Construction and materials: A tandrem typically consists of high-strength rubber reinforced with fibers such as fiberglass, Kevlar, or steel cords. The inner surface has teeth that mesh with pulley grooves, while the outer surface is covered by a protective, heat- and oil-resistant layer. The belt is designed to withstand heat, oil exposure, and mechanical stress within the engine compartment.

Function and maintenance: The belt, along with tensioner and idler pulleys, forms the core of the timing system. In many vehicles, the belt also drives auxiliary components or is linked to the water pump. Replacement intervals vary by manufacturer but commonly fall in the range of 60,000 to 100,000 miles (approximately 96,000–160,000 km). Signs of wear include cracks, fraying, glazing, or missing teeth. In interference engines, a belt failure can cause severe valve damage, leading to costly repairs.

Replacement considerations: It is often recommended to replace the belt together with the tensioner, idler pulleys, and sometimes the water pump to reduce the risk of future service needs. Some engines use a timing chain instead of a belt, which has different maintenance implications.

See also: Timing chain, Serpentine belt, Engine timing.