Mechanical damage to the bearing seat refers to the appearance of varying degrees of grooves on the alloy surface of the bearing, and in severe cases, metal peeling and large areas of messy scratches on the contact surface; In general, both contact surface damage and ablation occur simultaneously. The main reason for mechanical damage to bearings is that the surface of the bearing is difficult to form an oil film or the oil film is severely damaged.

（2）轴承穴蚀

(2) Bearing pitting

轴承座在气缸压力冲击载荷的反复作用下，表面层发生塑性变形和冷作硬化，局部丧失变形能力，逐步形成纹并不断扩展，然后随着磨屑的脱落，在受载表面层形成穴。一般轴瓦发生穴蚀时，是先出现凹坑，然后这种凹坑逐步扩大并引起合金层界面的开裂，裂纹沿着界面的平行方向扩展，直到剥落为止。Tr轴承座穴蚀的主要原因是，由于油槽和油孔等结构要素的横断面突然改变引起油流强烈紊乱，在油流紊乱的真空区形成气泡，随后由于压力升高，气泡溃灭而产生穴蚀。穴蚀一般发生在轴承的高载区，如曲轴主轴承的下轴瓦上。

Under the repeated action of cylinder pressure impact load, the bearing seat undergoes plastic deformation and cold work hardening on the surface layer, losing local deformation ability, gradually forming wrinkles and continuously expanding, and then forming cavities on the loaded surface layer as the debris falls off. When the bearing shell undergoes pitting corrosion, pits first appear, and then these pits gradually expand and cause cracking at the alloy layer interface. The cracks propagate parallel to the interface until they peel off. The main reason for the pitting corrosion of Tr bearing seats is that the sudden change in the cross-section of structural elements such as oil grooves and oil holes causes strong turbulence in the oil flow, forming bubbles in the vacuum zone where the oil flow is disrupted. Subsequently, due to the increase in pressure, the bubbles collapse and pitting corrosion occurs. Cavitation usually occurs in the high load area of bearings, such as the lower bearing shell of the crankshaft main bearing.

（3）疲劳点蚀

(3) Fatigue pitting

轴承疲劳点蚀是指，由于发动机超负荷工作，使得轴承工作过热及轴承间隙过大，造成轴承中部疲劳损伤疲劳点蚀或者疲劳脱落。这种损伤大多是因为超载轴承间隙过大，或者润滑油不清洁内中混有异物所致。因此，使用时应该注意避免轴承超载工作不要以过低或过高的转速运转；怠速时要将发动机调整到稳定状态；确保正常的轴承间隙，防止发动机转速过高或过低；检查调整冷却系统的工作情况，确保发动机的工作温度适宜。

Bearing fatigue pitting refers to the phenomenon where the engine operates under overload, causing overheating and excessive bearing clearance, resulting in fatigue damage, pitting, or fatigue detachment in the middle of the bearing. This kind of damage is mostly caused by excessive clearance between overloaded bearings or impurities mixed in the lubricating oil due to unclean lubrication. Therefore, when using, attention should be paid to avoiding bearing overload and not operating at low or high speeds; When idling, adjust the engine to a stable state; Ensure normal bearing clearance to prevent engine speed from being too high or too low; Check and adjust the operation of the cooling system to ensure that the engine's operating temperature is appropriate.

（4）轴承合金腐蚀

(4) Corrosion of bearing alloy

轴承合金腐蚀一般是区为润滑油不纯，润滑油中所台的化学杂质（酸性氧化物等）使轴承合金氧化而生成酸性物质，引起轴承合金部分脱落，形成无规则的微小裂孔或小凹坑。轴承合金腐蚀的主要原因是润滑油选用不当轴承材料耐腐蚀性差，或者发动机工作粗暴温度过高等。

Corrosion of bearing alloys is generally caused by impure lubricating oil, and chemical impurities (such as acidic oxides) in the lubricating oil oxidize the bearing alloy to form acidic substances, causing partial detachment of the bearing alloy and the formation of irregular small cracks or pits. The main reason for corrosion of bearing alloys is improper selection of lubricating oil, poor corrosion resistance of bearing materials, or rough engine operation with high temperatures.

（5）轴承烧熔

(5) Bearing melting

轴颈和轴承摩擦副之间有微小的凸起金属面直接接触，形成局部高温，在润滑不足冷却不良的情况下，使轴承合金发黑或局部烧熔。此故障常为轴颈与轴承配合过紧所致；润滑油压力不足也容易使轴承烧毁。

There are small raised metal surfaces in direct contact between the journal and the bearing friction pair, forming local high temperatures. In the case of insufficient lubrication and poor cooling, the bearing alloy may become black or locally melt. This fault is often caused by the tight fit between the shaft neck and the bearing; Insufficient lubricating oil pressure can also easily cause bearing burnout.

（6）轴承走外圆

(6) Bearing outer circle

轴承走外圆就是轴承在座孔内有相对转动。轴承走外圆后，不仅影响轴承的散热，容易使轴承内表面合金烧蚀，而且还会使轴承背面损伤，严重时烧毁轴承。其主要原因是，轴承过短凸榫损伤加工或者安装不符合规范等。

The outer circle of the bearing refers to the relative rotation of the bearing within the seat hole. After the bearing passes through the outer circle, it not only affects the heat dissipation of the bearing, which is easy to cause alloy erosion on the inner surface of the bearing, but also damages the back of the bearing, and in severe cases, burns out the bearing. The main reason is that the bearing is too short and the tenon is damaged during processing or installation, which does not comply with the specifications.