The Expanding Shaft (OEM Part No. 3128310598) is a mechanical spare component compatible with Simba M4C,Simba E70, Simba E7C, Simba M40S, Simba H1354, SIMBA H1254, underground drilling rigs. Manufactured from high-strength alloy steel, it is designed for the rock drill assembly rotation unit position. The expanding shaft supports mechanical expansion and rotational functions, providing accurate movement and stable operation within the drilling system. Its durable design ensures precise fitting, high load resistance, and extended service life in harsh underground mining environments.