In HC25 Hydraulic Rock Drills, the O’ring 86770898 is designed for low-pressure hydraulic port sealing, a critical role in preventing oil loss and debris intrusion. Generic O-rings made from low-grade rubber often swell or harden within 400-500 hours, especially in contact with mineral oil. This OEM O’ring uses high-quality NBR rubber blended with reinforcing agents, enabling it to withstand temperatures from -20℃ to 100℃ and maintain ≤20% compression set over 800 hours. Its precise dimensional tolerance (±0.002mm) ensures a tight fit with HC25’s port specifications, eliminating leakage risks.