To prevent the possibility of an air lock, the hydraulic system has a small leak off at the top of the exhaust valve hydraulic cylinder. Oil is made up via a non return valve. A relief valve is also fitted. A damping arrangement on top of the piston in the exhaust valve prevents hammering of the valve seating.The valve spindle is fitted with a winged valve rotator. The kinetic energy in the exhaust gas rotates the valve a small amount as it passes. This keeps the valve at an even temperature and helps reduce the build up of deposits on the valve seat.The cage of the exhaust valve is of cast iron as is the guide. The renewable valve seat is a hardened molybdenum steel and the valve spindle can be a molybdenum chrome alloy with a layer of stellite welded onto the seating face, or alternatively a heat resistant nimonic alloy valve head, friction welded to an alloy steel shaft.When the valves are overhauled, the valves and seats are not lapped together. Instead special grinding equipment is used to grind the seat and spindle to the correct angles.
đang được dịch, vui lòng đợi..