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A Camshaft is a shaft in the engine, which has a series of cams for operating the valve mechanisms. The camshaft is driven through gears by the crankshaft and mounts overhead on top of the cylinder head.

  • Some engines use a combination of timing chain and timing belt to drive the camshafts.
  • When the camshaft is driven by a timing chain, the crankshaft and camshaft rotate in the same direction.
  • With gear, the camshaft rotates in the opposite direction. Most camshafts have a cam for each valve in the engine.

Composition of a Camshaft

  • In addition, the camshaft has another cam to operate the fuel pump.
  • It also has the gear to drive the ignition distributor and the oil pump.
  • The camshaft sprocket or gear is twice as large as the crankshaft sprocket. It gives a 1:2 gear ratio, which means the camshaft turns half the speed of the crankshaft in a four-stroke cycle engine.
  • Thus, every two crankshaft revolutions give one camshaft revolution and one cycle of valve action.