Truck scale and load cell glossary
What the words mean
35 terms you will meet while specifying, installing or operating an industrial scale — defined without assuming you already know the next one. Nothing here is a Thurman specification; figures live on the product pages.
Whether a scale may legally be used to set a price is a separate question from whether it is accurate, and it is answered by a different body in each country.
- Legal for trade
A weighing device is legal for trade when it has been approved for use in commercial transactions where the weight determines the price. Approval is granted per device type by a national or state authority, not by the manufacturer.
If you sell by weight — grain, aggregate, scrap, waste — the scale almost certainly has to be legal for trade. If you weigh only for your own process control, inventory or safety, it may not need to be.
- NTEPNational Type Evaluation Program
The United States program that evaluates weighing and measuring device types against NIST Handbook 44. It is administered by the National Conference on Weights and Measures (NCWM). A device type that passes is issued a Certificate of Conformance.
NTEP evaluates the device TYPE, not each unit shipped. Individual installations are still verified and sealed locally by the state or county weights-and-measures official.
- Certificate of ConformanceCC number
The certificate NTEP issues to a device type that has passed evaluation, identified by a number such as 89-016. Quoting the CC number is how a manufacturer evidences a legal-for-trade claim, and a claim without one is not evidenced.
- Measurement Canada
The Canadian federal agency responsible for weights and measures. A device used in trade in Canada requires Measurement Canada approval.
NTEP approval does not clear a device for commercial use in Canada, and Measurement Canada approval does not clear it for the United States. They are independent approvals with separate numbers, and a device may hold one, both or neither. Any product presenting a single merged "certified" claim across both countries is telling you less than you need to know.
- NIST Handbook 44HB-44
The United States technical standard that sets the specifications, tolerances and other requirements for weighing and measuring devices. It is the document NTEP evaluates against and the one a state inspector works from.
- Accuracy class
A classification that sets how many scale divisions a device may have and what tolerance applies across its range. Class III covers most commercial retail and industrial weighing; Class IIII is typical for vehicle and axle-load scales.
A higher class is not automatically better — it is a different set of requirements for a different application. What matters is that the class matches how the scale will be used and what it will be sealed for.
- Calibration
Comparing a scale against known reference weights and adjusting it so its readings fall within tolerance. On a legal-for-trade scale, calibration is performed by a licensed service provider and the result is sealed.
Calibration is periodic maintenance, not a one-time commissioning step. Intervals are driven by the jurisdiction, the application and how hard the scale is worked.
The parts of the scale that carry the load, and the words used for the choices between them.
- Weighbridge
The platform a vehicle drives onto — the structural deck and the beams under it. It carries the load and transfers it to the weighing elements beneath.
- Load cell
The sensor that converts force into an electrical signal. A truck scale carries the deck on several load cells, and the indicator sums their signals into one weight.
Load cells are the part of a scale most exposed to what happens on site: impact, water, corrosion, lightning and rodents. Most service calls on an electronic scale come down to a cell, a cable or a connection.
- Double-ended shear beam
A load cell supported at both ends with the load applied at its center, commonly used in vehicle scales. The mounting hardware usually allows the deck to move slightly and return to position.
- Rocker column
A load cell design in which a column stands between two bearing surfaces and returns to vertical under load. Used in vehicle scales, typically mounted so cells can be reached from the side of the platform.
- Section
One weighing station of a truck scale — a pair of load cells and the span of deck they support. A long platform is made of several sections, and a vehicle is weighed as its axles pass across them.
Sections matter for service because a fault is usually in one of them. How easily you can identify which one is a real difference between scale designs.
- Concentrated Load CapacityCLC
The heaviest load a deck is rated to carry concentrated over a short span — an axle or axle group — rather than spread across the whole platform. For heavy off-road traffic it is usually the figure that governs, not the total capacity.
CLC and nominal capacity answer different questions. Total capacity is about the heaviest complete vehicle; CLC is about what a single heavy axle does to the deck it is standing on. A scale can have ample total capacity and still be under-specified for a loaded haul truck.
- Nominal capacity
The total weight a scale is rated to weigh, usually stated in tons. It is the headline capacity figure and is not a substitute for concentrated load capacity.
- Checking
The hardware that limits how far a weighbridge can move horizontally when a vehicle brakes, accelerates or turns on it — check rods, bumper bolts or a linked suspension. Without it, side and braking loads reach the load cells.
- Self-restoring
A suspension design in which the weighbridge returns to its centered position on its own after being pushed out of it, rather than needing to be reset. Relevant wherever traffic brakes or turns on the deck.
- Steel deck
A weighbridge whose driving surface is welded steel plate, supplied complete from the factory. It can carry traffic as soon as it is set and connected.
- Concrete deckfield pour
A weighbridge shipped as steel modules with the concrete driving surface poured on site after installation. The pour has to cure before the scale carries traffic.
The choice between steel and concrete deck is usually about schedule, site access and what the local trades can do, rather than about capacity.
- Above-ground scale
A scale set on foundations at or slightly above grade, reached by ramps or earth approaches. The underside stays open, so cells and cabling can be reached and water drains away.
- Pit scale
A scale installed in a concrete pit so its deck sits flush with the surrounding surface. It needs no ramps and suits sites where vehicles must cross it from several directions or space is tight.
A pit needs drainage and access designed in from the start. Anything that collects in a pit has to be got out of it, and a technician has to be able to reach the cells.
- Low profile
An above-ground scale built to a reduced deck height, so the approaches can be shorter and the whole installation takes less room.
- Portable scale
A scale built on a self-contained sub-frame so it can be relocated without being rebuilt. Used where the weighing point moves — a pit that works out, a seasonal site, a job with an end date.
- Approach
The paved or compacted run of ground leading onto the scale. Its length, level and condition affect both weighing accuracy and how long the deck and its checking hardware last.
What reads the load cells, what it does with the number, and how the two are connected.
- Indicatorinstrument
The unit that reads the load cells, converts their signals into a weight, displays it, and drives whatever happens next — printing a ticket, releasing a gate, sending the record to a system.
- Analog load-cell interface
A connection in which load cells send their low-level analog signals to a junction box, which sums them and passes one analog signal to the indicator. The indicator does the conversion to a digital value.
- Digital load-cell interface
A connection in which the analog signal is converted to a digital value out at the scale, and the indicator receives digital data. Because each signal is identified in the data, a fault can be traced to a specific position rather than inferred.
- Intalogix
A digital load-cell communication system in which analog signals are digitized at scale-mounted controllers and sent to the indicator as data, allowing section-by-section calibration and diagnostics.
- Smart Sectional ControllerSSC
The scale-mounted unit in an Intalogix system that digitizes the load-cell signals for its section and communicates them to the indicator.
- Junction box
The enclosure on the scale where load-cell cables meet and their signals are combined before going to the indicator. On analog scales it is also where sectional trimming is adjusted.
- Remote display
A large-format display mounted where the driver can read it, showing the weight from the indicator so the vehicle can be positioned or released without the driver leaving the cab.
- NEMA rating
A North American classification of how well an enclosure resists dust, water and corrosion. NEMA 12 is an indoor rating covering dust, falling dirt and dripping non-corrosive liquids. NEMA 4X adds windblown dust, rain, splashing and hose-directed water, plus corrosion resistance.
The rating describes the enclosure, not the whole installation. Cable entries, mounting and where the unit is actually put determine whether the rating means anything in practice.
- IP69K
An ingress protection rating for equipment that must withstand high-pressure, high-temperature washdown. Used for components cleaned with pressure washers, including sealed load cells.
- Tare, gross and net
Gross weight is the loaded vehicle. Tare is the empty vehicle. Net is the difference — the product. A weigh ticket normally records all three, and which one is measured versus stored differs by operation.
- In-motion weighing
Determining weight while the vehicle is moving across the scale rather than stopped on it. Approval requirements for in-motion weighing differ from those for static weighing.
- Axle-load weighing
Weighing individual axles or axle groups, rather than the whole vehicle at once, to check compliance with axle-weight limits. Whether the result can be used to set a price depends on how the device is approved.
Talk it through with someone who does this daily
Tell us the site, the traffic and what you weigh for. A Thurman sales engineer will size the scale with you and connect you with your local distributor.