Automatically adjust the injection advance Angle according to the speed change. Most in-line pumps use centrifugal mechanical advancer. Installed between the driving wheel (timing gear) of the oil pump and the camshaft of the oil pump, the camshaft Angle relative to the driving wheel is changed by using the balance relationship between the centrifugal force and spring force in the advance device, so as to meet the requirement that the injection advance Angle increases with the increase of rotating speed.