Load cell

 A load cell is a transducer that is used to convert a force into electrical signal. This conversion is indirect and happens in two stages. Through a mechanical arrangement, the force being sensed deforms a strain gauge. The strain gauge converts the deformation (strain) to electrical signals. A load cell usually consists of four strain gauges in a Wheatstone bridge configuration. Load cells of one strain gauge (quarter bridge) or two strain gauges (half bridge) are also available. The electrical signal output is typically in the order of a few millivolts and requires amplification by an instrumentation amplifier before it can be used. The output of the transducer is plugged into an algorithm to calculate the force applied to the transducer.
Although strain gauge load cells are the most common, there are other types of load cells as well. In industrial applications, hydraulic (or hydrostatic) is probably the second most common, and these are utilized to eliminate some problems with strain gauge load cell devices. As an example, a hydraulic load cell is immune to transient voltages (lightning) so might be a more effective device in outdoor environments.
Other types include piezoelectric load cells (useful for dynamic measurements of force), and vibrating wire load cells, which are useful in geomechanical applications due to low amounts of drift.
Every load cell is subject to "ringing" when subjected to abrupt load changes. This stems from the spring-like behavior of load cells. In order to measure the loads, they have to deform. As such, a load cell of finite stiffness must have spring-like behavior, exhibiting vibrations at its natural frequency. An oscillating data pattern can be the result of ringing. Ringing can be suppressed in a limited fashion by passive means. Alternatively, a control system can use an actuator to actively damp out the ringing of a load cell. This method offers better performance at a cost of significant increase in complexity.

Load Cell types based on working principle

• Cantilever or bending beam
• Compression
• Tensile
• Universal
• Shear
• Torque
• Hollow

Load Cell types based on construction

• Bending beam
• Parallel beam or Binocular Beam
• Canister
• Shear beam
• Single column
• Multi-column
• Pancake
• Load button
• Single ended shear beam
• Double ended shear beam
• "S" type
• Inline rod end
• Digital ElectroMotive Force
• Diaphragm/membrane
• Torsion ring
• Bending ring
• Proving ring
• Load Pin

Load Cell types based on electrical properties

• Resistive
• Piezoelectric
• Capacitance
• Analog
• Digital
• Wireless

Applications

• Force measurement
• Portable weigh scales
• Platform scales
• Electronic weighbridge or truck weighing
• Electronic crane scales
• Hopper/Tank/Silo weighing
• Finding Center of gravity
• Onboard weighing
• Railcar weighing
• Structural health monitoring
• In-motion dynamic weighing check weigher
• Batch weighing
• Monitor inventory
• Feedback control
• Impact measurement
• Force gauge