The Thrust Bearing 86668860 absorbs axial forces generated by the HC25 Hydraulic Rock Drill’s reciprocating piston, a role critical to reducing friction and extending piston life. Generic thrust bearings use low-grade steel that wears rapidly—often within 500-600 hours—leading to increased noise and piston damage. This OEM bearing is made from high-carbon chromium bearing steel (GCr15) with a hardness of HRC 60-65, ensuring wear is limited to ≤0.005mm over 800 hours. Its precision design fits HC25’s piston assembly perfectly, maintaining smooth movement until mandatory replacement.