Abstract: A circuit for controlling a motor having an armature and a series-wound, series-connected field coil that can be separately controlled during regenerative braking. The circuit includes a main switching circuit, an armature circuit, and a field circuit. The main switching circuit includes a first switch and a first diode parallel-connected to the first switch. The armature circuit includes a second switch parallel-connected to the armature and series-connected to the main switching circuit, and includes a second diode parallel-connected to the second switch. The field circuit includes a third diode parallel-connected to the field coil and series-connected to the armature circuit.

Abstract: An air tool torque control system includes a controller operative to independently control two air tools with continuous programmed adjustment of the torque shut off point for each tool after each fastener joint is made. The torque specification is measured for each fastener joint made, is verified as being within an acceptable torque range, is compared to the set point of that torque specification range to determine the variation therebetween, and is then adjusted toward the mid point by the applicable correction factor for the variation determined to continuously compensate for variations in joint rate, line pressure and/or tool output. To enhance the effectiveness of the system, fast acting solenoid valves utilizing line pressure to assist in valve closure may be included to improve shut off control.