In HC50 Hydraulic Rock Drill (or Hydraulic Drifter) operations, the Retainer chuck 86706793 is the “connection anchor” between the drill and the shank—it clamps the shank tightly to prevent slippage during high-torque drilling (critical for breaking hard rock) and ensures impact force is fully transferred to the drill bit. With over a decade in mining equipment maintenance, I’ve seen generic retainer chucks fail rapidly: most use low-hardness metal for the gripping cavity, which wears down in just 80-120 hours. This leads to shank slippage, uneven drill holes, and even damage to the shank’s outer surface (a $1,000+ replacement cost). Worse, a loose retainer chuck can cause the shank to dislodge mid-drilling, posing safety risks to operators.