Erosion can occur when particles move at high speeds hit surfaces and wear or pitting them away. Flow controls and relief valves are most commonly the most sensitive to erosive wear. 

 

Spool values, specifically proportional and servo types, can lose receptivity or bind completely as a consequence of significant silt build up. The extremely fine particles that make up silt can be present in the environment or can be created within a system in large quantities. These valves can also be affected by abrasion. 

 

Things like bearings amongst other components can be subject to heavy load which can cause metal fatigue. If hard particles become stuck in between two surfaces it can create cracks that continually expand which will result in spalling. Increasing the useful life of essential bearings can be achieved by improving the cleanliness of the oil used. The useful life of these bearings can be increased substantially through the use of better dirt exclusion techniques and better filtration.