Kampiakselin

Kampiakseli (camshaft) is a shaft in internal combustion engines that carries cam lobes. The lobes push on valve lifters or followers to open intake and exhaust valves, while the valve springs close them. The camshaft's profile determines valve timing and lift, shaping engine breathing and performance.

Operation and timing: In most four-stroke engines, the camshaft rotates in sync with the crankshaft via timing belt, chain, or gears. The camshaft's rotation angle determines when each valve opens and closes; typically the camshaft turns at half the crankshaft speed, ensuring each valve opens once every two crank revolutions. The timing must be precise to avoid valve-piston interference.

Configurations and location: The camshaft can be located in different places: overhead cam (OHC) engines place one or more camshafts in the cylinder head; in DOHC engines there are separate camshafts for intake and exhaust. In pushrod engines (OHV), the camshaft is in the engine block and actuates valves through pushrods and rocker arms.

Construction and maintenance: Camshafts are typically made of steel or cast iron; high-performance units may be hardened or alloyed. They are lubricated by engine oil. Wear on lobes or followers can degrade timing and engine performance. Modern engines may use variable valve timing (VVT) which adjusts cam timing during operation.

History and significance: The camshaft is a core component of most internal combustion engines since the early 20th century, enabling precise control of valve events. Alternatives such as camless systems have been researched but remain uncommon in production.