The piston is the largest wear parts of the piston ring groove wear. The main reason is that the gas pressure causes the piston ring to increase the unit pressure of the annular groove and at the same time, the piston ring makes a great impact on the annular groove due to the high speed reciprocating motion of the piston. In addition, the high temperature of the combustion gas causes the piston head The working temperature is high, and the closer to the top of the piston the higher the temperature and gas pressure. Therefore, the first ring groove wear the most serious, the following ring groove wear gradually reduced. Ring groove wear is mainly under the plane, while less wear on the plane, so that the ring groove wear large trapezoidal inside and outside, the piston ring backlash increases, causing the cylinder gas channeling and channeling oil.

Piston head in the work due to the supporting role of the piston ring rarely contact with the cylinder wall, the wear and tear is small.

Although the piston skirt contact with the cylinder wall, but the pressure per unit area is not large, lubrication conditions are better, so less wear and tear, usually in the side to withstand lateral wear and abrasion prone. When the piston skirt and cylinder wall clearance is too large, the engine prone to knock cylinder, and the phenomenon of serious channeling oil, therefore, the engine overhauls mainly depends on the piston and cylinder wall clearance and cylinder wear degree.

Piston at work, due to the role of gas pressure inertia force, the piston pin hole oval wear occurs, the maximum wear parts of the seat hole is up and down direction, so that the piston and pin loose loose Kuang, abnormal noise.