This setup Hough section of the sealing ring so that the first seal and the second seal is installed in the opposite abutment incomplete or do not stick together, close together, the sealing effect of the seal through the seal and Huff's Day achieved with the structure of the housing, thereby sealing the housing cooperates with greatly improved high pressure performance and resistance to water hammer Hough section performance to ensure the sealing performance Hough section ductile iron exists in the form of spherical graphite , its mechanical properties far superior to steel gray iron and closer, it has excellent casting, machining and wear resistance, have a certain flexibility, widely used in the manufacture crankshafts, gears, pistons and other senior castings, and a variety of mechanical parts .