HBM U10M, Mounting Instructions, Page: 12 / 128

U10M, U10S
12
A1385-6.2 en/de/fr HBM
3 Structure and mode of operation
3.1 Transducers
The measuring element is a steel loaded member made of steel (for nominal
(rated) forces from 12.5 kN) or high‐strength aluminum (for nominal (rated)
forces up to 5 kN) to which strain gauges (SG) are applied. The SG are
arranged in each measuring circuit so that four are stretched and the other
four compressed when a force acts on the transducer. Each strain gauge
changes its ohmic resistance in proportion to its change in length and so mis­
aligns the Wheatstone bridge. If there is an excitation voltage, the circuit pro­
duces an output signal proportional to the change in resistance and thus also
proportional to the applied force. The arrangement of the SGs is selected so
that parasitic forces or torques and temperature influences are essentially
compensated for.
3.2 SG cover
To protect the SG, the force transducers have thin cover plates that are wel­
ded (steel versions) or glued (aluminum versions) top and bottom. This pro­
cedure offers the SG a high protection against environmental influences. In
order to retain the protective effect, these plates must not be damaged in any
way.