Timing chains connect the crankshaft and camshaft(s) within the engine, synchronizing valve and piston movement. Unlike timing belts, they utilize hardened steel links for increased durability and longevity, often requiring less frequent replacement. These chains operate within a dedicated housing, typically lubricated by engine oil, and incorporate hydraulic tensioners to maintain proper slack. Multi-link designs and specialized coatings are common features intended to reduce friction and wear. Variable valve timing (VVT) systems frequently integrate with the timing chain to adjust camshaft phasing for optimized engine performance.