In HC25 Hydraulic Rock Drill (or Hydraulic Drifter) operations—especially in wet mining environments (e.g., underground tunnels, rainy surface quarries)—the Seal kit 86726734 (water seal kit) is a “first-line defense” against water and dust. It’s responsible for sealing the drill’s waterway connections, preventing moisture from mixing with hydraulic oil (which causes oil emulsification and pump failure) and stopping dust from scratching precision components like the piston or valve. With over a decade in mining equipment maintenance, I’ve seen generic water seal kits fail in as little as 80-100 hours: their low-quality rubber hardens quickly in water, leading to leaks that damage the hydraulic system—costing mines $2,500+ in repairs and 1-2 days of downtime.