Explain how the 'Number of Turns' ($n$) in a spiral retaining ring affects the distribution of shear stress across the ring's cross-section.

In a multi-turn spiral ring, the axial load is distributed across all turns. However, because the turns are connected in a continuous spiral, the shear stress is not perfectly uniform. The first turn (closest to the load) typically carries a slightly higher percentage of the load. The total shear area is $A_s = n \cdot π \cdot D \cdot t$. For a 2-turn ring, the shear capacity is double that of a single-turn ring of the same thickness. This allows for very high thrust capacities in a thin radial profile. In heavy-duty mining equipment, 3-turn or 4-turn rings are used to distribute the immense axial loads over a larger groove surface area, preventing groove wall failure.