In HC109 Hydraulic Rock Drill (or Hydraulic Drifter) systems, the pin 86318516 is a “critical structural connector”—it’s installed between movable components (e.g., the boom and drill head, or linkage parts) to lock their relative positions and transmit small loads. During drilling, it endures constant vibration (up to 1600 bpm) and shear force; a faulty pin can cause component misalignment, noisy operation, or even sudden disconnection (posing safety risks to operators). With over a decade in mining equipment maintenance, I’ve seen generic pins fail repeatedly: most use low-strength carbon steel that bends or cracks in 500-700 hours, forcing unplanned downtime and $1,800+ in repairs (from damaged linked components).