US Patent 7921940 Casing hammer power swing-out apparatus for drilling rig

A swing-out apparatus for a drill rig, typically for drilling water wells. It includes a sled which is formed to be driven vertically on a drill mast of a vehicle carrying the sled, a casing hammer, and a hinge securing the casing hammer on the sled. To provide for displacement of the casing hammer relative to the sled, a drive is provided for swinging the casing hammer on the hinge from a deployed position to an inactive position. The drive comprises a motor connected for driving one relative to another.