1. Large hexagonal bolts must be able to pass through the bolt holes at will. Oxygen cutting cannot be used for reaming of high-strength bolt holes, and the amount of reaming should be carried out according to the design of the construction project. The diameter of the hole after reaming needs to be as low as possible. In 1.2D. 2. Every time the operation reaches 12,000km, the large hexagonal bolts need to be maintained at the second level. The hex bolts should be equipped with an oil pan, and then check the condition of the piston pins. If the gap between the piston pins is too large, replace them, and replace the connecting rod bolts at the same time. If the engine is found to be abnormally noisy and unstable during daily operation, it must be inspected in time. 3. Every time the maintenance is carried out, the new connecting rod bolts need to be inspected again. It is also necessary to check the guiding position of the hexagon bolt, the top of the thread head, etc., whether there are pits or cracks in these positions, and whether the tooth pitch and the tooth profile of the thread are normal. If there is any abnormality in the above parts, it cannot be used again. 4. When installing the connecting rod bolt cover, it must be carried out with a torque wrench. When tightening, it must be in accordance with the specified specifications, and the torque should not be too large or too small. 5. Maijin pointed out that the large hexagonal bolts of the crankshaft should be manufactured by supporting facilities. 6. After the large hexagonal bolt is installed as a spherical joint, the spherical joint must be firmly connected with the high-strength bolt, and the high-strength bolt must be screwed into the bolt ball, so the length of the external thread should exceed 1.0d, and the length of the joint There is no looseness or gaps in the area. 7. The friction surface that must be connected by large hexagonal bolts should be clean and dry, without welding slag, burr, welding spatter, compound scale, shiny, waste, etc. Unless there are special circumstances, it cannot be painted.