In HC25 Hydraulic Rock Drill (or Hydraulic Drifter) systems, the Diaphragm kit 86633922 (nitrogen diaphragm) is a “pressure regulator” for the accumulator—it separates nitrogen from hydraulic oil, ensuring the accumulator maintains stable pressure to buffer the drill’s impact force (critical for consistent drilling performance). With over a decade in mining equipment maintenance, I’ve seen generic diaphragm kits fail prematurely: most use low-elasticity rubber that hardens or cracks in 400-500 hours, leading to nitrogen leakage. This causes the accumulator to lose pressure, reducing the drill’s impact power by 30% or more, and forcing frequent system repressurization (wasting time and increasing labor costs). Worse, a broken diaphragm can mix nitrogen with hydraulic oil, damaging the pump and valve (a $3,000+ repair).