Abstract: A mechanical jar used primarily on drill strings, in earth boreholes, to aid in freeing drill strings stuck in a well bore. A telescoping drill string component is constrained in a selected telescoped condition by a biased lock until enough axial stress is applied to the telescoped jar to release the lock. Energy stored in the stressed length of drill string then moves rapidly to strike a solid limit to the telescoping travel. The inertia of the moving part of the drill string applies a shock to the stationary, downwardly continuing part of the drill string. The shock is to aid in releasing the stuck string situation. The tension required to release the lock is adjustable, as a design alternative, by applying torque to the drill string. The jar can, by design alternative, be used to strike in either or both axial directions.

Abstract: Back-up power tongs are provided, for holding a tubular member, such as a drill pipe, against rotation of a connected tubular member, the back-up tongs comprising a body, having a center opening of sufficient size for the tubular member to pass therethrough, a slot communicating between the edge of the body and the center opening, and a cavity disposed within the body. A plurality of jaw members are disposed within the body around the perimeter of the center opening, each jaw member having a concave surface generally conforming to the curvature of the tubular member and facing the interior of the opening so as to be grippingly engageable with the tubular member. At least one cylinder assembly is disposed within the cavity and fixedly connected to one jaw member so as to extend or retract the jaw member on a radial path centered at the center of the tubular member.

Abstract: A power tong having a frame with an open throat at one end and a pipe gripping mechanism situated for rotation within the frame, carrying three pipe gripping dies about equally spaced around the longitudinal axis of the pipe. Only one of the pipe gripping dies is driven toward the pipe by cam action of the rotating mechanism. The other two pipe gripping dies pivot and achieve their pipe loading capability from the action of the cam driven pipe gripping die. Once the rotation of the pipe has been achieved, the rotating mechanism returns to such a position that the open throat of the rotating mechanism coincides with the open throat of the frame, whereby the pipe, having been spun, can then be released.

Abstract: A jaw assembly is provided for gripping tubular members, particularly pipes. The assembly comprises a jaw member, which is attachable to a conventional gripping mechanism, and a removable die which is attachable to the jaw member. The jaw member is provided with a concave surface having parallel grooves which are radially spaced over the concave surface. The die is provided with a convex surface conforming to the curvature of the concave surface of the jaw member. The convex surface of the die is provided with splines which are alignable with and matingly insertable within the grooves on the jaw member. The die is also provided with a concave surface conforming to the radial curvature of the pipe or other tubular member to be gripped.