For a long time before, bottom CFMoto Camshaft Timing Sprocket were the most common in internal combustion engines. Usually in such an engine, the valve is located on the top of the engine, which is the so-called OHV (OverHead Valve) engine. At this time, the camshaft is usually located on the side of the crankcase, and the valve is controlled by the valve mechanism (such as tappet, push rod, rocker arm, etc.). Therefore, the bottom camshaft is generally called side camshaft. Since the camshaft is far from the valve in such an engine, and there are usually only two valves per cylinder, the speed is usually slow, the ride comfort is poor, and the output power is relatively low. However, the output torque and low-speed performance of the engine with this structure are better, and the structure is relatively simple and easy to maintain.
The engines of most production cars are now equipped with overhead camshafts. The overhead CFMoto Camshaft Timing Sprocket structure makes the camshaft closer to the valve, reducing the waste of reciprocating kinetic energy of the bottom camshaft due to the larger distance between the camshaft and the valve. Engines with overhead camshafts have faster valve opening and closing actions, so the speed is higher and the running smoothness is better. The engine with the overhead camshaft structure that appeared earlier is the SOHC (SingleOverHeadCam, overhead single camshaft) engine. This engine only has one camshaft installed on the top, so generally there are only two to three valves per cylinder (one or two for intake and one for exhaust), and high-speed performance is limited. The newer technology is the DOHC (DoubleOverHeadCam, overhead double camshaft) engine, this engine is equipped with two CFMoto Camshafts, each cylinder can be installed four to five valves (intake two to three, exhaust Qi two), the high-speed performance has been significantly improved, but at the same time the low-speed performance will be affected to a certain extent, the structure will become complicated and difficult to repair.