Abstract: The electric circuit of the torque indicator in a torque wrench is automatically adjusted by the electric circuit of a detachable adjusting and calibrating instrument which is separably connectable to the wrench so that its torsion bar is deformable by the torque applicator wrench. Each circuit includes a microprocessor with means for displaying the measured torque, and interfaces are provided to separably connect the microprocessors to each other preparatory to an adjusting or calibrating operation. Each circuit further comprises one or more bridge circuits with strain gages, amplifiers for signals at the outputs of the bridge circuits, and analog-digital converters for transmission of signals from amplifiers to the respective microprocessor.