Cavitation damage to the cylinder block and cylinder liners of a small loader can cause cracks and even through-holes, ultimately leading to coolant entering the cylinder and engine oil, significantly reducing the diesel engine's lifespan and reliability. The primary cause of cavitation is cylinder liner vibration.
When the piston reaches top dead center, the direction of the side pressure changes, causing the piston to swing from one side of the cylinder liner to the other, resulting in piston wobble. Because of the thermal gap between the piston and cylinder liner, this piston wobble is impactful. This impact causes strong vibration of the cylinder liner.
When the cylinder liner wall vibrates, alternating stretching and compression occur in the water cavity, creating localized high pressure and vacuum bubbles in the water near the outer wall. Under this high vacuum, coolant evaporates into bubbles. Some vacuum bubbles and air bubbles occur in tiny pinholes on the outer wall of the cylinder liner, or are forced into these pinholes by the vibration.
When a vacuum bubble or air bubble ruptures under high pressure, a pressure shock wave is generated near the rupture zone. This shock wave can reach tens of atmospheres and impacts the outer wall of the cylinder. Frequent and repeated impacts cause rapid damage to the cylinder liner surface. To prevent cavitation erosion, the most common methods are: reducing the clearance between the cylinder and piston to reduce cylinder liner vibration; using a longer piston skirt; increasing the cooling water flow rate and improving the water flow direction and cooling system structure; increasing the support stiffness of the cylinder liner; and improving the materials and manufacturing process of the cylinder liner to enhance its resistance to cavitation erosion.
The causes of cylinder liner cavitation erosion in small loaders are as described above. Once this phenomenon occurs, timely repair is essential, but prevention is also crucial.
