The Ring 86676889 secures roller thrust bearings in HC25 Hydraulic Rock Drills, preventing axial movement that could disrupt bearing alignment and increase wear. Generic bearing rings are often thin and deform within 1500-1800 hours, leading to bearing misalignment and premature failure. This OEM ring is made from thick alloy steel (≥5mm) with a hardness of HRC 40-45, ensuring it resists deformation under load. Its precision-machined inner diameter (tolerance ±0.003mm) fits the bearing outer race perfectly, maintaining stable positioning until wear or deformation requires replacement.