Official Answer
Answer
For a spiral retaining ring to function at its rated thrust capacity, the groove depth $d$ must be precisely controlled. Typically, the groove depth is set such that 70-80 percent of the ring's radial wall $b$ is submerged. A common specification is $d = (b - clearance)$. If a chamfer is present on the retained part (the component the ring is holding), it must be kept to a minimum. The maximum allowable chamfer $c_{max}$ is calculated as $c_{max} = 0.5 \cdot (b - d)$. If the chamfer is too large, it creates a 'wedge' effect that exerts a radial outward force on the ring, potentially popping it out of the groove under axial load. In such cases, a square-edged backup washer must be used between the chamfered part and the ring.
