Compact casing tongs for use on top head drive earth drilling machine

Casing tongs for a drilling machine of the type comprising a mast and a top head drive assembly movable along the mast, wherein the top head drive assembly comprises a quill and means for rotating the quill, said casing tongs comprising:

• a tube having an upper end, a lower end, and a side wall;
• a quill connector body having an upper end, a lower end, and a passageway extending therebetween, the upper end of the quill connector body shaped to engage and mate with the quill and the lower end of the quill connector body shaped to fit within an upper end of a length of casing which comprises a casing body and a casing collar;
• means for rigidly mounting the quill connector body to the upper end of the tube;
• a seal plug mounted to the lower end of the quill connector body and shaped to engage and seal against the upper end of the casing collar;
• an injector tube secured to the lower end of the quill connector body in alignment with the passageway to conduct drilling fluid from the passageway into the casing body;
• a plurality of cams positioned within the tube and rigidly secured to the lower end of the tube, said cams defining a plurality of recesses arrayed around a central opening sized to admit the casing collar into the tube;
• a plurality of jaws, each positioned in a respective one of the cam recesses and each defining a respective inner surface shaped to engage the casing body;
• a brake ring disposed around the tube outside the tube;
• means for coupling the brake ring to the jaws such that the brake ring and the jaws rotate together yet radial movement of the jaws with respect to the brake ring is accommodated;
• a disc brake mounted to a nonrotating element outside the tube to frictionally retard rotation of the brake ring when the tube is rotated by the quill;
• and
• spring means coupled to the jaws to bias the jaws to a retracted position, out of contact with the casing body;
• said disc brake and brake ring cooperating with the cam to move the jaws into engagement with the casing body when the brake is set and the tube is rotated in either direction by the quill, thereby causing the jaws to grip the casing body for rotation by the top head drive assembly.

Casing tongs for a drilling machine of the type comprising a mast and a top head drive assembly movable along the mast, wherein the top head drive assembly comprises a quill and means for rotating the

• quill, said casing tongs comprising:
• a rigid tube having an upper end and a lower end, said tube being sized to receive and surround an upper end of a length of casing which comprises a casing collar and a casing body;
• means for securing the upper end of the tube to the top head drive assembly such that the tube is suspended therefrom and rotation of the quill causes rotation of the tube about a central axis;
• a plurality of jaws, each configured to engage an exterior surface of a length of casing;
• means for supporting the jaws in the tube for limited rotational and radial movement to engage the casing body below the casing collar, said supporting means comprising a plurality of cams, each cam being positioned adjacent a respective one of the jaws, each cam being shaped to shift the respective jaw radially in response to relative rotation between the cam and the respective jaw;
• and
• brake means, coupled between the jaws and a non-rotating element external to the tube, for selectively retarding rotation of the jaws when the tube is rotated by the quill and the brake means is set,
• said supporting means and brake means cooperating to shift the jaws radially inwardly to clamp a casing body for rotation when the tube is rotated by the quill and the brake means is set.