Abstract: A borehole sensor is presented including a three axis gimbal device for determining (1) a vertical plane, using the force of gravity as a reference, (2) a horizontal plane, using the force of gravity as a reference, and (3) the north direction, using the earth's magnetic field as a reference. A motor drive system drives parts of the mechanism to desired positions about the three axes, and error transducers determine the deviation from desired positions about the axes and provide feedback to the motor drive system to eliminate the error.

Abstract: A rotation sensor and output signal processing apparatus is presented. The rotation sensor is a ring core flux gate magnetometer whose output varies as a function of the earth's magnetic field. The phase angle of the second harmonic of the magnetometer output is sensed to provide an indication of the state of rotation of the magnetometer. When a state of no rotation is sensed, actuating signals are delivered to a control system to sense borehole parameters and telemeter the parameters to the top of the borehole.

Abstract: A control system is presented for controlling the operation of a borehole sensor. The borehole sensor includes a three axis gimbal device for determining (1) a vertical plane, (2) a horizontal plane, and (3) the north direction. Upon receipt of an initiation signal, the control causes a motor drive associated with each gimbal to drive error transducers on each gimbal to desired "home" positions about the three axes and error transducers determine the deviation from desired positions about the axes and provide feedback to the motor drive system to eliminate error. A home signal is generated when each error transducer reaches its home position. When home signals are received from all error transducers, the control system then senses the sign and magnitude of the error output from each error transducer and operates the motor drive system to drive the gimbals in directions to reduce the error. When each error transducer reaches its null position, the control terminates operation of its associated motor drive.

Abstract: This invention concerns a device to block at a given torque a rotating machine driven by a hydraulic or gas turbine.The device comprises means of separating a driven disc from a driving disc, consisting of the insertion between the two discs of at least three balls or the like, which roll along three inclined cavities sloping in opposite directions when the longitudinal reaction resulting from the driven-shaft torque exceeds the force of a calibrated spring; these means co-operate with a disc brake fixed to the driven shaft, and which increases the driven-shaft torque.This device is used in particular to block, outside operating periods, driven appliances connected with a hydraulic turbine operated by drilling mud in equipment at the bottom of wells to measure and transmit drilling parameters and characteristics.

Abstract: A mud pulse telemetry system is presented for transmitting information from the bottom of a well hole to the surface. The mud pulse telemeter is a pilot operated valve which restricts the flow of mud in the drill string to set up pressure waves in the mud stream which can be detected at the surface. The pilot operated mud pulse telemeter uses a small input signal to operate the telemeter valve by pressure differentials created in the mud stream itself.