Abstract: A method and apparatus for sensing a drill pipe joint is characterized by an arm pivotally moveable with respect to a drill pipe from a first, normal, position. The arm deflects a predetermined angular distance from the normal position when it comes into contact with a predetermined distended location on a drill pipe. An electrical signal is generated by a signal arrangement associated with the arm to indicate that the predetermined distended location is reached.

Abstract: Apparatus for controlling a tongs arrangement which includes a tongs lift and lift speed arrangement, a backup tong and a power driven tong, is characterized by means for generating electrical signals to lift the backup tong and power tong at a predetermined speed to a predetermined elevation, means for generating an electrical signal to close and lock the backup tong when lifted, and means for generating an electrical signal to drive the power driven tong when the backup tong is closed and locked.

Abstract: An oil drilling rig includes a racker, a power tongs, a drawworks having a motor and a brake, and a general purpose programmable digital computer associated with each to sequentially initiate the operation thereof. Closed-loop control systems for the drawworks motor and drawworks brake are included to provide control signals to a motor drive and to a brake actuator.

Abstract: A manually operable valve in a power tongs assembly has, in combination therewith, an electro-hydraulic interface module. The interface module comprises an electrically responsive solenoid valve connected in hydraulically parallel path to the manually operated valve. The manually operated valve may be selectively disenabled and the electrically responsive valve simultaneously enabled to permit electrical control of the power tongs assembly.

Abstract: A computer-controlled oil drilling derrick is characterized by apparatus for determining the load supported by a traveling block during motion thereof from a first to second position within an oil drilling rig. The apparatus is operative to output a signal functionally related to the net load on the traveling block. Further, the apparatus outputs an appropriately scaled signal functionally related to the load on the traveling block when in a substantially static condition.

Abstract: A computer - controlled oil drilling rig is characterized by apparatus for comparing signals representative of the actual velocity and direction of travel of a traveling block with signals representative of predetermined minimum and maximum velocities of the traveling block and a signal representative of a predetermined direction of travel of the traveling block. Output signals are generated if the actual velocity signals are greater than the maximum velocity signal or less than the minimum velocity signal and if the direction of the traveling block deviates from the predetermined direction.

Abstract: Apparatus for indicating the position of a traveling block along a vertical axis within a computer-controlled oil drilling rig is characterized by a magnetically responsive element for generating a pulse when a metallic member, movable with the traveling block, passes in proximity thereto. A counter is operatively associated with the magnetically responsive element to count the pulses therefrom. An electrical signal of a predetermined magnitude functionally related to the output of the counter is representative of the position of the traveling block.

Abstract: In a hydraulically powered pipe handling system, a general purpose digital computer is used to control the operation of hydraulically powered racker arms as well as the various auxiliary functions involved in vertical piperacking operations. The manual pipe-racking system (that is, that which is hydraulically powered and under the control of one or more operators) is retained, the computer controlled mode of operation being an alternative system present in the overall design.There is provided to the operator, while the system is in its automatic mode of operation, visual indication of length of drill string, depth of hole, depth of drill bit and composition of the drill string, including number and type of pipe lengths making up the drill string.