Abstract: The hand-operated ratchet spanner contains a measuring value pick-up (4,9) for the angle of rotation of the screw and a device for measuring the torque. The measured values are supplied to a microprocessor (22) in which the screw tightening operation is preprogrammed by respective desired or limit values. Signal lamps (30,31,32) or acoustic signal transmitters (33) indicate to the user as to whether the screw has been correctly tightened. Further, he may recognize the extent to which the screw has been tightened and which part of the tightening operation must be still effected.

Abstract: The control device controls the sewing speed of a sewing needle automatically in a manner such that the temperature of the sewing needle, subjected to the influence of heat generated by friction with the material being sewn, does not exceed an adjustable predetermined value. Respective measuring members determine the temperature of the sewing needle and the temperature of a reference needle mounted at a location spaced from the sewing needle, and are connected to the input of a differential comparator circuit providing the differential voltage of the measuring members. A signal generator is operatively associated with the sewing needle and produces output pulses responsive to reciprocation of the sewing needle, to control connection of the output of the differential comparator circuit to the input of the sewing machine motor control. The reference needle is substantially identical with the sewing needle.