Method of and apparatus for measuring and setting the tension of stressed members

Apparatus for setting a wire-like element which is responsive to magnetic fields at a desired tensioned condition which includes, in combination:

• a magnetic transducer having an air gap for receiving such an element and being of a size to permit the element to vibrate freely therein at its resonant frequency,
• means for mounting a wire-like element so as to extend through the air gap of the magnetic transducer and without a potential drop across that portion of the element extending through the gap,
• means for producing a pulsating magnetic flux field in said air gap operating at the frequency coinciding with the resonant frequency of the element received therein, and
• means for varying the tension of the element while subjected to the pulsating magnetic field until the condition of resonance is exhibited by the element.

Apparatus for affecting the tension of a magnetically responsive wire-like element comprising, in combination:

• a magnetic resonator including an energizing coil enclosing a portion of a body of magnetic material having an air gap for receiving such an element, the air gap being of a size to permit the portion of the element received therein to accommodate the displacements of the element at its natural frequency,
• means for mounting a wire-like element so as to extend through the air gap of the magnetic resonator and without the application of a potential drop over that portion of the element extending through the gap,
• an oscillator circuit connected to the coil and operable to produce current pulses in the coil of substantially square shape and all of one polarity for generating a pulsating magnetic field of the same frequency in the air gap,
• means in the oscillator circuit for varying the frequency of the current pulses delivered to the coil for similarly varying the frequency of the magnetic field generated in the air gap, and
• means for varying the tension of the wire-like element received in the air gap of the magnetic resonator while subjected to the pulsating magnetic field generated in the air gap.