Explosion-Proof Stop Ring of Atlas Copco RD18U in South Africa

South Africa's deep-level gold mining—at depths exceeding 3,500 meters in the Witwatersrand Basin—operates under some of the most demanding occupational safety regulations for mining equipment globally. The Mines Health and Safety Act and the associated equipment standards apply to all powered equipment underground, including hydraulic rock drills. For equipment used in mines classified as potentially flammable or with rock burst risk, the stop ring in the RD18U drifter's percussion mechanism carries a classification significance beyond its mechanical function.

The stop ring is the component that limits the percussion piston's rearward travel on the return stroke—it catches the piston at the end of its designed stroke envelope and prevents it from over-traveling into the rear housing. In a standard mining application, a failed or missing stop ring leads to piston impact on the rear housing bore face, which generates metal particle contamination in the hydraulic oil and eventually produces percussion bore scoring. In a deep South African gold mine where methane levels require monitoring and where rock burst events can suddenly depressurize drilling circuits, a physically secure stop ring that stays in place under shock loading is a safety component, not just a wear component.

Stop Ring Function and Inspection Points

South African mine engineering standards require inspection of percussion stop rings at every scheduled percussion maintenance event—not on a separate interval. The paperwork trail that AngloGold and Harmony operations require for underground percussion equipment maintenance now includes specific stop ring condition recording as a line item. HOVOO supplies RD18U stop rings manufactured to the dimensional and material specifications required for South African deep-level mining compliance. Full documentation available on request at hovooseal.com.