The camshaft is usually located at the top of the cylinder, while the crankshaft is usually located below the cylinder, connected to the piston.
The camshaft controls the opening and closing of the intake and exhaust valves at the right time,while the crankshaft is used to convert the reciprocating motion of the piston into rotating motion.
The camshaft rotates by a timing belt attached to the crankshaft, which rotates by work done by a piston.

Camshafts are mainly divided into overhead camshaft(OHC) and Overhead valve(OHV) in terms of their positions. According to the connection type, it is mainly divided into hydraulic camshaft and tappet camshaft.

· mechanical interferences

· insufficient lubrication

· inferior quality

· improper installation

· old or worn components

Repairing a camshaft is not often advisable,due to the manufacturing processes.

The main advantage of the overhead camshaft is that it increases the natural frequency of the valve mechanism. The resulting improved dynamic characteristics of the valve drive mechanism make it possible to design camshaft profiles to extend the effective operating range of high speed engines.