... by supplier alloy steel, using advanced mechanical technology and heat treatment method to get high degree, dimensional accuracy ... , high strength and toughness, the surface hardness not less than HRC60.The ... 7", 140, 150, 170, 2303Valve assenbly: valve, seat and rubber4Crosshead5Extension rod6Crosshead Assembly7Gasket 8Oil seal 9O-ring 10Bearing 11Upper guide ...