Sensitive elastic ring 1, of an in su latin g m aterial, has a uniform
layer of carbon paste 5 applied to its inner surface. A t four points
(at 90° intervals), the paste is in contact w ith flexible leads.
O btained thus are four sections of resistance which ^constitute
the four arms of a Wheatstone bridge. If rin g 1 is deformed by
a p p ly in g forces to lugs a, which are attached to the item being
tested, one pair of carbon sections is stretched and the other
pair is compressed. The resistance of the first pair correspondingly
increases and that of the second pair decreases, thereby
changing the electrical state of the measuring bridge. The flexible
leads connect the carbon sections to the power source 3
and to high-resistance potentiometer 2, which serves to zero
measuring instrument 4. The readings of instrument 4 indicate
the forces app lied to the item being tested.
$4354$SmE,M$