Cavitation damage of cylinder block and cylinder liner of small loader will cause cracks and even through holes, resulting in cooling water entering the cylinder and engine oil, and then significantly reduce the service life and working reliability of diesel engine. The main cause of cavitation is the vibration of cylinder liner.

当活塞到达上止点的时候，侧压力的作用方向发生另外变化，活塞从缸套的一面横摆到另外对面，就出现了活塞摆的现象。由于活塞跟缸套之间留有热间隙，所以活塞的摆动还是有冲击性的。这种冲击引起缸套的强烈振动。

When the piston reaches the top dead center, the action direction of the side pressure changes. The piston swings from one side of the cylinder liner to the other side. Because there is a thermal gap between the piston and the cylinder liner, the swing of the piston is still impulsive. This impact causes strong vibration of the cylinder liner.

当缸套壁振动时，水腔中发生交替的拉伸和压缩，从而使外壁附近的水域中产生局部的高压和真空泡。在高真空的作用下，冷却水蒸发成气泡，有的真空泡和气泡发生在气缸套外壁微小的针孔中，或者是在振动的作用下被挤入针孔。

When the cylinder liner wall vibrates, alternating tension and compression occur in the water chamber, resulting in local high pressure and vacuum bubbles in the water near the outer wall. Under the action of high vacuum, the cooling water evaporates into bubbles. Some vacuum bubbles and bubbles occur in the tiny pinholes on the outer wall of the cylinder liner, or are squeezed into the pinholes under the action of vibration.

当真空泡或气泡受到高压冲击而破裂时，就在破裂区附近产生压力冲击波，其压力可达数十大气压并冲击气缸外壁，这样频繁的反复冲击，就使缸套表面急剧损坏。我们为了防止穴蚀，目前常用的方法是：减小气缸与活塞之间的间隙，从而减小缸套的振动；采用长的活塞裙部；加大冷却水流速，改进水流方向及冷却系的结构；增加气缸套的支承刚度；改进气缸套的材料及工艺，以提高其抗穴蚀能力等等。

When the real bubble or bubble is broken by high-pressure impact, a pressure shock wave will be generated near the fracture area, and its pressure can reach tens of atmospheres and impact the outer wall of the cylinder. Such frequent repeated impact will sharply damage the surface of the cylinder liner. In order to prevent cavitation, the commonly used methods are: reduce the gap between cylinder and piston, so as to reduce the vibration of cylinder liner; Adopt long piston skirt; Increase the flow rate of cooling water, improve the flow direction and the structure of cooling system; Increase the support stiffness of cylinder liner; Improve the material and process of cylinder liner to improve its cavitation resistance, etc.

小型装载机的气缸套穴蚀的原因就是上面介绍的这些，再出现了这种现象之后一定要及时修理，但是预防也是关键。

The reasons for the cavitation of cylinder liner of small loader are those described above. After this phenomenon occurs again, it must be repaired in time, but prevention is also the key.