Where measurement is necessary, this mechanism could be preferable to a turnbuckle.
The figure illustrates a simple mechanism designed for anchoring one end of a cable on a structure and for adjusting the tension in the cable. Unlike turnbuckles and other conventional cable-tensioning mechanisms, this mechanism also facilitates direct measurement of the tension in the cable. Several of these mechanisms are used in concert in order to suspend a structure for thermal isolation.
The bracket is used to secure the mechanism to the anchoring structure. The near end of the cable is threaded through the mechanism and tied off in a loop at the pin in the stopper. The tensioner bolt is turned counter-clockwise in the bracket until the bored conical hole at its outer end mates with the conical surface of the stopper, placing the cable in tension.
Further counter-clockwise rotation of the tensioner bolt increases the tension. The tension can be measured directly by simply pulling on the cable with a force gauge; the tension equals the measured force that is just sufficient to unseat the stopper. Once the specified tension has been achieved, the tensioner bolt is locked in place by tightening the jam nut against the bracket.
This work was done by Ross G. Iacomini of Johnson Space Center. For further information, access the Technical Support Package (TSP) free on-line at www.nasatech.com/tsp under the Test & Measurement category. MSC-22704