The original air-loaded Tensiometer was developed in the late 1940s. The design was very clever, as it established a pivot center for the deflector roll assembly whereby the unit gave output signal almost independent of wrap angle. The geometry of this Tensiometer has withstood the test of time, and most modernized versions simply replace the air cylinders or "pots" with load cells, and in some cases apply wrap angle compensation to the output of the load cells.
In 1990, T. Sendzimir, Inc. developed the "Flexpivot" Tensiometer in which the pivoting arm comprises a flexure pivot bearing block. This device appears quite like a standard bearing block, but it compensates for wrap angle error from empty mandrel up to full coil diameter.
This design has the following characteristics: