In HC20 Hydraulic Rock Drill (or Hydraulic Drifter) systems, the Spline shank 86677184 is a “torque transmission core”—it connects the drill’s drive system to the shank, transferring rotational torque to drive the bit while guiding the shank’s reciprocation. Montabert sets an 800-hour replacement cycle because its spline teeth wear gradually: after 800 hours, tooth wear depth often reaches 0.2mm+, reducing torque transmission by 18-22% and causing shank jitter.

1. Wear resistance: Heat-treated alloy steel (HRC 48-52) ensures teeth last the full 800-hour cycle.
2. Precision fit: Tooth pitch tolerance ±0.003mm, matching HC20’s drive system perfectly to avoid jitter.
3. Torque stability: Reinforced tooth root design prevents tooth breakage under high torque.