DK28 diesel Engine parts introduces the main repair techniques of valves and seats

Before maintenance, measure whether the distance between the bottom surface of the air valve and the bottom surface of the cylinder head exceeds the requirements. If the difference in this value is too large, it will affect the compression ratio of the diesel engine and the impact of the valve and the piston, so the valve seat cushion must be replaced. During maintenance, the following measurements should be carried out on the air valve after long-term work: roundness error and cylindricity error after valve stem wear, which can be measured by measuring inspection such as external micrometer. When the two errors exceed 50% of the clearance limit with the conduit, they should be scrapped and replaced. The radial runout of the enlightening cone to the outer cylinder of the valve stem should not be greater than 0.003mm. Otherwise, it should be scrapped and replaced.

During the inspection, the gas valve top is placed between the spindle head and the tail thimble of the lathe, the two thimbles are top of the gas valve in the original processing top pinhole, the dial indicator is mounted on the drag plate, and the contact of the table is in contact with the valve cone. During the rotation of the valve, the reading change of the dial indicator, the maximum and maximum value is the radial runout. At this time, the clamping state of the air valve is checked for cracks, pitting and pits. The outer surface of the valve stem is allowed to have less than 10 hairlines and the length does not exceed 20mm. Magnetic inspection and demagnetization should be carried out on the cone surface and the valve stem connection lock clip. Cracks should be scrapped.