US Patent 7165759 Crown block dead line anchor

The line system on a drilling rig is arranged to place the dead line clamp at the upper end of the derrick. A dead line anchor sheave is preferably located to accept wraps of the dead line to insure reduced load on the dead line clamp. The anchor sheave is preferably lockable to prevent rotation and releasable to rotate the anchor sheave for line feeding from a reserve line reel for maintenance operation. A load sensor is optionally provided to sense dead line load for sensing associated hook loads on the traveling block. An motor is provided, as an option, to rotate the anchor sheave for line feeding maintenance operations.