(1) wear and tear gear wear Parts of the gear wear mainly tooth meshing, involute face and gear both ends of the plane. Slight wear, the tooth surface can be whetstone grinding, both ends of the flat grinding on the flat light. Serious wear gear teeth should be replaced with new gear, if only the ends of the gear wear, grinding grinding in the surface grinder. After changing the gear mapping, the modulus m = 3, the number of teeth z = 12, the tooth angle α = 20 °, the tooth top height coefficient f0 = 1, the tooth positive displacement coefficient x1 = x2 = 0.5, The dimensions are calculated as follows. Index circle diameter: d = mz = 3X 12 = 36 (mm) Tip height: ha = m f0 + x = 3X l + 0.5 = 4.5 mm Root height: hf [= m (f0 5 + 2. 25 = 6. 75 (mm) The diameter of the tip circle : Da = d + 2ha = 36 + 2X4.5 = 45 (mm) Fixed chord thickness: Sxn = m (π / 2 * cos2a + xsin2 a) = 3 X (1.387 +0.6428X0.5) = 5. 125 (mm) fixed tooth thickness measurement tooth height: hxn = m (π / 8 * sin2a + xsin2 a) = 3X (0. 7476X0 117X0 5) = 2. 42 Bit factor x0.5 Tooth profile o20 ° Fixed chord thickness Sxn5 .12 Teeth height coefficient f1 Fixed chord thickness measurement Highest tooth height hxn2. 42 Number of teeth z12 (2) Maintenance after shaft wear Gear shaft wear mainly It is because the friction between the two ends of the shaft and the supporting needle roller wear, so that the shaft diameter becomes smaller. If it is slightly worn, the shaft can be enlarged by plating a hard chrome to make the shaft repaired. If the shaft wear serious, 45 steel or 40Cr steel should be re-manufactured, shaft rough rough, fine car, the bearing parts to be heat treated, the hardness of HRC60-65, and then grinding, the bearing surface roughness Ra with parts Greater than 0.32μm; shaft roundness and cylindrical tolerance of 0.005mm; with the gear with the H7 / h6, the surface roughness Ra should not exceed 0.63μm. (3) After the pump body wear repair The pump body surface wear is mainly oil-absorbing section arc-shaped working surface.If there is slight wear, can be used whetstone after grinding grinding to use. The pump body is made of cast iron casting blank, severe wear and tear should be replaced when the new pieces. If both ends of the gear in the pump are repaired by grinding, the width of the pump should be changed to the same size as that of the two ends of the gear. The two ends of the pump after reworking should meet the technical requirements as shown in Fig.3. (4) After the wear of the two end caps Repair gear pump end caps made of cast iron, wear phenomenon, the slight flat grinding on the flatner, the more serious wear and tear should be ground in the surface grinder smoothing. After grinding the end cap and the pump body with the connection plane contact should not be less than 85% flatness tolerance, the end of the hole centerline vertical tolerance, the tolerance of the parallelism of both ends and the center of the two axis hole Line parallel tolerance are O.Olmm. After grinding the surface roughness Ra should not be greater than 1. 25μm. (5) maintenance of needle roller bearings Pump replacement parts in the repair, the needle roller bearings should be replaced. Needle on the needle is: the size of the needle roller diameter error should not exceed 0.003mm, the length tolerance of 0.1mm, and the shaft with the gap should be around O.Olmm; needle roller assembly according to the number of requirements filled bearing shell, Needle roller to be arranged parallel to each other.