The Motor Shaft 86668696 transmits torque from the hydraulic motor to the transmission system of HC25 Hydraulic Rock Drills, a role requiring high strength and precision. Generic motor shafts made from low-alloy steel often bend or wear within 1800-2200 hours, causing vibration and noise. This OEM shaft is crafted from 40CrNiMo alloy steel with a tensile strength of ≥900MPa and undergoes precision grinding to achieve a journal surface roughness of Ra≤0.2μm. It maintains smooth rotation and torque transmission until bending, wear, or noise indicates replacement is needed.