Abstract: A system for controlling the operation of a motor being used for the rotational assembly or dis-assembly of two members, the system comprising means monitoring, and generating a digital or analogue signals representative of the state of the two members and means relaying the representative signal in a digital form to a first processor (6) means relaying the signal in an analogue form to a second processor (11); the first processor comprising a computer which in use, digitally analyses the representative signal and is so programmed as to generate a first control signal in response to the representative signal; the second processor comprising means converting the first control signal into analogue form and means comparing it with the analogue representative signal and generating second control signal representative of the difference between the first control signal and the representative signal; the second processor being so connected as to transmit the second control signal to the motor control means.

Abstract: A device for applying torque to e.g. a screw-threaded pipe includes a pair of gripping jaws pivotally mounted on a cage and carrying respective followers engaging cam surfaces on the radially inner surface of a rotary drive member. The jaws have friction linings. The case is connected to a clamp on the pipe so as to prevent rotation of the cage relative to the pipe. When a rotary drive is transmitted to the drive member, its cam surfaces operate the gripping jaws to clamp them about the pipe and increases the clamping pressure until the pipe begins to rotate with the drive member. The rotary drive member is mounted on a primary support which is held against rotation about the pipe and provides the required reaction force for the rotation.