Official Answer
Answer
Some high-load applications use a two-piece 'interlock' ring, where two separate spiral rings are wound together into the same groove. This effectively doubles the shear area and the thrust capacity. The installation involves winding the first ring into the groove, followed by the second ring, ensuring their ends are phased $180^{\circ}$ apart. This phasing is critical to ensure a uniform $360^{\circ}$ retention and to prevent any 'gap' in the retaining surface. This method is common in heavy industrial presses where the cost of a single extremely thick ring would be prohibitive, or where the assembly requires the flexibility of a spiral ring but the strength of a heavy shoulder.
