In the 1980s and 1990s, for electronic truck scales in China with a maximum capacity of up to 100 tons, the commonly chosen weighing sensors were designed based on the beam shear stress principle, mainly including single-shear cantilever and double-shear beam bridge structures. Single-shear beam weighing sensors use a rocker column pressure head to transmit the load, while double-shear beam weighing sensors use a steel ball to transmit the load. However, as users' demand for the weighing range of electronic truck scales increased, expanding from 100 tons to 200 tons, shear-structure weighing sensors could no longer meet market needs. Due to their unique characteristics, column-type weighing sensors have been selected by most electronic truck scale manufacturers.

   Shear stress itself cannot be measured, but the principal stress it generates at a 45° angle to the neutral axis of the shear beam can be measured. The principal stresses that appear in tension and compression pairs are precisely what a weighing sensor requires to form a Wheatstone bridge. The cross-sectional shape of the strain beam in a shear stress weighing sensor determines the distribution of shear stress in the strain region, mainly including single shear stress—such as in a cantilever beam structure, and double shear stress—such as in a bridge structure. In particular, a double-shear beam weighing sensor consists of a strain beam with an I-shaped cross-section in the strain region, a base, double-end fixing screws, and steel ball push heads for load transfer. To overcome the drawback of the large gradient in shear stress distribution in a rectangular cross-section shear beam, four blind holes are symmetrically machined on the two sides of the beam between the center loading point and the two support points of the rectangular strain beam. This transforms the cross-section of the strain beam from rectangular to I-shaped, forming a local I-beam section, making the shear stress distribution of the I-shaped cross-section much more uniform than that of a rectangular cross-section.
   When subjected to tensile and compressive loads, the volume of the elastic element remains the same, meaning the cross-sectional area of the strain region does not change, so the behavior is linear.
  The shear force along the length of the beam is constant, and the output is independent of the bending moment, so it is not sensitive to changes in the loading point. It has been observed that for a weighing sensor of this type used for more than a year, with a loading point on a 20-ton weighing sensor, the steel ball indentation is about 20 mm in length, and during subsequent verification, it can still maintain good metrological performance.
  The loading points and support points form a self-balancing force system. Due to the weight of the bridge-type weighing sensor itself and the configured base plate, it can be placed on the foundation plate without being affected by the movement of the weighing platform and is easy to install.
  The steel ball and the ball seat have point contact and are well-aligned. The steel ball only bears axial loads and does not transmit lateral loads, ensuring measurement accuracy. Moreover, the bottom of the bridge-type weighing sensor is relatively large. When installed on the base plate, the friction generated by its own weight prevents any movement in all directions. Its main function relies on the steel ball rolling as the load carrier moves.
  For an electronic truck scale with a maximum capacity of 60 tons, the load-bearing platform is 18 meters long, divided into three overlapping sections, and equipped with eight load cells each with a maximum capacity of 25 tons, intended for use in environments with a temperature variation of 50°C.