1.DOHC
DOHC (Double Overhead Camshaft) in Chinese meaning is double overhead camshaft.
Because the double camshaft Valve overlap angle can be changed, it can play a large horsepower, torque but low speed but also because of lack of comparative complex mechanical structure may cause some difficulties in maintenance. DOHC art from the car, the main intake valve can be controlled with the time difference between the exhaust valves.
intake and exhaust valves in the breakdown of two camshafts. All the valve plunger is driven by the former through a cam shaft, but in a different port in the valve location, operation accuracy can not be maintained, the effect is slightly less, which does not have this disadvantage can be obtained more good performance, but with a need multiple camshafts, which is double overhead camshaft (DOHC), recently introduced a new engine adopt this form. In general, DOHC movement is relatively high, more F1 racing applications, but due to the complex manufacturing process, high cost; SOHC opposed to the relatively simple, the use of better durability, either adapt to the general customer power requirements, It can also be adapted to the requirements of its economy.