A temporary method of supporting a circular shaft sinking. It consists essentially of iron curbs or rings. Each ring consists of segments of wrought iron, 3 to 5 in (7.62 to 12.7 cm) deep, 5/8 to 7/8 in (1.59 to 2.22 cm) thick, and from 6 to 8 ft (1.82 to 2.44 m) in length. The segments are bent to the curvature of the shaft and bolted together, each ring being suspended from the ring above. Laggings or backing deals are wedged behind the rings. Every fourth ring or so is supported on steel strata bolts driven into holes drilled in the rock sides.