The timing  pulley is an important part of the engine's air distribution system. It is connected to the crankshaft and matched with a certain transmission ratio to ensure the accuracy of the intake and exhaust time. Use belts instead of gears to drive because the belt has low noise, small changes in itself and easy compensation.

The function of jacking up the intake valve is to let the atomized gasoline enter the cylinder block. When jacking up the exhaust valve, it is to let the exhaust gas exit the cylinder block. , Exhaust valves are closed, the compression ratio is generated, the distributor ignites, internal combustion starts and generates power.