Abstract: A drill pipe spinner having a body with an open throat for receiving a drill pipe. A pair of cylindrical driven rollers are mounted on the body for rotation about a vertical axis. A pair of pressure arms are pivotally mounted on the body for rotation about a primary pivot pin. A pair of secondary pressure arms are mounted on the primary pressure arms, for rotation relative to the primary pressure arm about a secondary pivot pin. A pair of cylindrical pressure rollers are mounted on the secondary pressure arms, for holding the drill pipe against the driven roller. A pair of piston and cylinder assemblies exert force on the secondary pressure arms, to cause the secondary pressure arms to rotate. The moment arms between the piston and cylinder assemblies and the primary pivot pins are shorter than the moment arms between the piston and cylinder assemblies and the secondary pivot pins.

Abstract: An interference warning device for an oil well drilling rig having a derrick, traveling equipment, a racker arm, and a block retractor. Fluid activated sensors provide electric signals when the traveling equipment is within a selected vertical distance from the racker arm, when the racker arm is within a selected horizontal distance from the vertical axis of the derrick, or when the block retractor has extended the traveling equipment to within a selected distance from the fully extended position. The operator is informed when any one of the sensors is activated, cautioned when any two of the sensors are activated, and warned when all three sensors are activated. The drawworks may be braked when all three sensors are activated.

Abstract: A well tool and method for making up and breaking out connections between sections of drill pipe. The tool will jump the upper pipe section out of the connection when the connection has been completely unthreaded, and will guide the upper pipe section during stabbing. A piston and cylinder assembly is mounted on the carriage for raising and lowering the pipe spinner relative to the carriage. The tool also has an actuator and a pilot valve for automatically opening the clamping cylinders of the spinner whenever the upper pipe section is raised by the pipe elevator.

Abstract: An improved seal assembly for a well head including a ring-shaped seal body positioned in the tubing head, a tubular coupling formed to the seal body and adapted to connect between adjacent portions of inner tubing, a lower seal ring positioned in the tubing head above the seal body and surrouding the coupling, a pliable rubber gasket positioned in the tubing head above the lower seal ring and surrounding the coupling, and an upper seal ring positioned in the tubing head above the gasket and surrounding the coupling. The seal body has a central circular opening and a radial slot for a cable. The lower seal ring has an inner circular section and an outer circular section split into an arcuate outer front section, and an arcuate outer rear section. The outer section has a semi-circular opening along the inner edge. The inner section is provided with a semi-circular opening on the outer edge which mates with the semi-circular opening on the outer section to form a passageway for the cable.