Importance

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Abstract

An apparatus for gripping a down hole tubular for rotation in a drilling machine includes a support member adapted for connection to the quill of the drilling machine. The support member supports three or more guides which converge toward one another in a selected direction. A clamping dog or engaging member is mounted to slide in each of the guides to move into engagement with a down hole tubular when positioned toward a first end of the guide and out of engagement with the down hole tubular when positioned toward a second end of the guide. A linkage interconnects the engaging members, and includes an acutating member exposed at an upper portion of the support member. This actuating member moves vertically along an axis between open and closed positions, which causes the engaging members to release or engage the tubular. The actuating member itself bears against an additional element on the top head drive assembly of the drilling machine which can be moved vertically to cause the clamping dogs to engage or release the tubular.

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First Claim