What is the reason for knocking in the cylinder? How to exclude?

Knocking sound in the cylinder may be:
1. The piston or piston ring is worn;
2. The piston ring gets stuck or the piston ring is broken;
3. Mechanical sundries fall into the cylinder;
4. Wear of cylinder or cylinder liner;
5. The axle-linkage mechanism is inconsistent with the center line of the cylinder;
6. The piston rod is bent or the piston rod nut is loose;
7. The volume of the cylinder's residual clearance passes;
8. Too much lubricating oil or too much water in gas will cause water strike;
9. Poor cooling and coking of lubricating oil;
10. The water in the water sleeve of the cylinder leaks into the cylinder;
11. Sound caused by poor work of suction and exhaust;
12. The piston or pin of the valve pressing device is loose;
13. The stuffing is damaged.
Exclusion method:
1. Repair the piston or replace the piston ring;
2. Eliminate mechanical impurities and accumulated oil and water in the cylinder;
3. Adjust the lubrication condition of the cylinder, and strengthen the cooling when necessary;
4. Check and adjust the concentricity between the crank-linkage machinery and the cylinder;
5. Correct the piston rod, and tighten the piston rod nut and piston nut;
6. Adjust the residual volume of the cylinder properly;
7. Check and repair the water jacket of the cylinder and the cylinder head, and replace the washer;
8. Repair or replace gas cutting;
9. Check and repair the door opening device;
10. Replace the stuffing.