| 摘要 |
A shoulder-type elevator is described. The elevator (10) has a frame (12) that supports a ring-shaped body (16) having an inwardly tapered interior surface. The body (16) is configured to receive a length of pipe a collar (C) with an outwardly protruding shoulder. A timing ring (42) supports a plurality of shoes (40) curvilinearly arrayed around the interior surface of the body (16). A set of timing ring cylinders with extendable and retractable piston rods (32) provide powered reciprocal movement of the over a desired range, and thereby powered reciprocal movement of the shoes (40), radially inward and outward around and below the shoulder of the pipe collar (C) within the interior of the ring-shaped body (16). Compression springs (54) mounted around each of the timing ring cylinder piston rods (40) provide an upward bias to the timing ring (42) at the end of its powered range of downward movement. The position of the shoes (40) within the ring-shaped body is configured so that the pipe collar will bear on the shoes to compress the upwardly biased compression springs (54) on the piston rods (32) of the timing ring cylinders. |
