On-board scales are devices for determining the approximate loaded weight of a truck. For many types of trucks, knowing the loaded weight is important for operating safely and maximising payload whilst avoiding fines for overloading. On-board scales use either

load cell A load cell converts a force such as tension, compression, pressure, or torque into an electrical signal that can be measured and standardized. It is a force transducer. As the force applied to the load cell increases, the electrical signal change ...

technology or pressure readings from

air suspension Air suspension is a type of vehicle suspension powered by an electric or engine-driven air pump or compressor. This compressor pumps the air into a flexible bellows, usually made from textile-reinforced rubber. Unlike hydropneumatic suspension, ...

to calculate the weight on the vehicle axles. Operating the truck at its optimal payload ensures that the owner minimises his running costs whilst maximising his profit. The convenience of being able to weigh at the loading site is a key factor in the popularity of on-board scales. This ability eliminates the costs associated with using an in-ground scale, such as lost

hours of service Hours of Service (HOS) regulations are issued by the Federal Motor Carrier Safety Administration (FMCSA) and govern the working hours of anyone operating a commercial motor vehicle (CMV) in the United States. These regulations apply to truck dr ...

, scale fees, and driver wages.

Types

There are four types of on-board scales in use:

Load-cell scales

Load-cell scales are based on electronic load cell transducers, and can be mechanical or strain-gauge. There is a wide variety of scale types that can be built with load cell technology. Typically load cells are used in payload scales for vehicles with spring suspension.

Air-suspension PSI gauges

Air-suspension PSI gauges are used on commercial trucks and semi-trailers where accurate weights are not as critical.

Air-suspension load scales

Load scales for air-ride applications that show on-the-ground weight in pounds (LBS) or kilograms (KG) instead of standard PSI. These non-electric gauges are analog (dial-face) with versions that can calibrate for accuracy.

Electronic scales with PSI sensors

Electronic scales with PSI sensors measure temperature and pressure changes in a vehicle's air suspension. It relays this data to a receiver hardwired into the cab, or wirelessly to a handheld unit, which interprets the data and displays an approximate axle weight or gross vehicle weight.
Wheel Loader Weighing

References

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MOBA Onboard scale for garbage trucks
Weighing instruments