How Do Scales Work?


Scales of all types, from a skewed spring scale hanging by the produce aisle to massive pit-and-girder monsters that weigh train cars and tractor-trailers, are the backbone of our modern world. No matter what shape or size they are, all scales work through devices called load cells that record the weight being measured.

Weight Measurement

Weight measurements can be made with a wide variety of mechanical and electrical scales. They are commonly referred to as balances and can range from small microbalances to industrial scales with weighing capacities of many tons. Most are calibrated using standard cast iron bar weights and should be tared (reset to read zero) on a regular basis.

The concept of weight measurement is important for children to understand at a young age. Students can learn that an object’s weight depends on gravity and is not affected by the size or shape of the object.

An understanding of weight and mass measurement will help them understand why a lion is heavier than a monkey and why the weight of an apple and the weight of a banana are different. This knowledge will allow them to make sound decisions about the health of themselves and others. It will also help them understand that an estimate of weight requires quality checking similar to other health related variables.

Load Cells

Load cells are the mechanical devices in weighing systems that sense force and transmit it in various forms for readout and recording. They are the cornerstone of most industrial, manufacturing and quality control-based weighing environments.

There are many different load cell types in use today, but they all work on the same basic principle of turning deflection into a change in resistance. Typically, they involve the use of one or multiple strain gauges within a mechanical setup (e.g., a bent helix or bent membrane) to detect the force that is being applied.

Hydraulic and pneumatic load cells have been growing in popularity due to their stability and lack of fluid leakage, but strain gauge technology is still the most commonly used in a wide range of applications, including tank level, truck scales and hoppers. They are also more resistant to overloads and metal fatigue than other load sensor technologies. They also feature a low profile, which makes them suitable for applications with limited space.


The most common scales used in medical, industrial and retail settings use devices called load cells to measure weight. They convert mechanical energy (the bending that occurs when an object is placed on the scale) into an electronic signal. The change in the signal is then converted into a digital weight reading.

Although there are many different types of digital scales, all work in similar ways. Most use a series of transducer beams that are engineered to bend in proportion to the amount of force being exerted on the weighing platform.

The change in the electrical signal caused by the bending of the beams is then converted into a weight reading using a microcontroller and a display. Because of this delicate internal design, it is important to handle your scales gently. Dropping, throwing or banging your scale can damage the sensitive sensors and cause inaccurate measurements. Also, temperature changes can affect the accuracy of a digital scale.


Scales are used to make precise measurements, but over time environmental factors may interfere with scale accuracy. Power fluctuations, aging of load cells, and even temperature changes can lead to inaccurate readings and equipment failure. Regular calibration, inspections, cleaning and lubrication are essential for maximizing the life of a scale.

Performing daily inspections and basic truck scale maintenance on a schedule or using a CMMS is the best way to ensure that minor issues do not turn into major problems. Keeping a truck scale log is also a great tool for recording and scheduling preventative maintenance.

Ensure the scale deck and junction boxes are clear of debris like dirt, rocks, and trash. Check for water pooling underneath pit-mounted scales and remove any trapped moisture. Also look for signs of corrosion on the understructure of the scale platform and the j-box board. Use a hose to wash the understructure of the scale to avoid mechanical binding.

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