Types of Load Cells

Load Cell

A strain gauge – elastic member combination arrangement used for the measurement of load or weight is called load cell. It utilizes an elastic member as primary transducer and strain gauge as a secondary transducer.

A suitable plane area is placed on the eleastic member as a weight stand. Then, strain gauge is attached to the elastic member.

Compression load cell Principle

Construction of Load Cell

The figure shown below is the Load cell Construction Diagram.On applying load, the elastic member will deform or deflect.

Since the strain gauge is attached to the elastic member, strain gauge may elongate or compress due to tension. This varies its length and in turn its resistance varies.

By measuring the variation in the resistance of the strain gauge, the applied load can be calculated.

Construction of Load Cell

The figure shows the construction of the tensile compressive cell which is a cylinder. This arrangement uses four strain gauges, each mounted at 90 to each other.

On applying load, due to tension, two of the strain gauges experience elongation or tensile stress while the other two are subjected to compression.

Since the load cell is cylinder, an axial compressive load causes a negative strain in vertical gauges and a positive strain in the circumferential gauges.

The two strains are not equal. By using bridge circuit, resistance of the strain gauge is measured and hence the unknown applied load.