Abstract: A system and apparatus for the monitoring and control of torque applied during make-up and breakout of drill string components. The force applied by the cat head to the tong is measured by a hydraulic load cell and the horizontal and vertical angles between the direction of the cat head pull and the longitudinal axis of the tong are measured by angle measuring devices. Force and angle values are used for calculating the correct value of the applied make-up or breakout torque. Force angle, and torque values at shut down or breakout may be displayed, printed and plotted. During make-up, the cat head is automatically disengaged at an instant calculated to achieve a desired make-up torque at the completion of shut down.

Abstract: An electrical motor or generator brush holder for containing a brush having a terminal external to the holder. The holder comprises an electrically insulative body with a head portion containing an internally threaded recess for mating with a threaded cap for retention of a brush within the body. The head portion includes a transverse slit configured to permit insertion and removal of the electrical terminal of the brush via the recess and not materially affecting the strength of the holder.