How Can Truck Scale Error Reduce Your Profit?
A small repeated deviation in each weighing transaction can accumulate into tons of material loss after hundreds or thousands of trucks.
A truck scale is not only a measuring device. In factories, mines, ports, raw material yards, batching plants, feed mills, cement plants, steel plants, agriculture, and logistics, the truck scale is often the point where goods are settled financially. Therefore, truck scale error is not only a technical issue, but also a direct profit-loss risk.
Repeated error40kg/truck1,000 trucks = 40 tonsVerification is not enoughStability must be monitored
A high-quality load cell helps improve truck scale stability, but real accuracy must still be controlled as a complete weighing system.
Key point: legal verification is necessary, but it is not enough. To protect profit, a truck scale must be stable, repeatable, and monitored for drift over time.
I. What is tolerance?
>. Tolerance is the permissible error of a scale at a specific test load. It is not one fixed value for all load levels. It is normally determined by the accuracy class of the scale, the verification scale interval, and the number of scale intervals corresponding to the test load.
n = Test load / verification scale interval e
For example, if the scale has e = 20kg and is tested at 20,000kg, the number of scale intervals at that load is:
n = 20,000 / 20 = 1,000 scale intervals
>. To understand permissible error, you must first know the scale accuracy class, the verification scale interval e, and the number of scale intervals at the actual test load.
II. Why can a scale within tolerance still lose money?
>. Assume a truck carries 20 tons of material. If the truck scale has a verification scale interval of e = 20kg and the permissible error at that load can reach 2 scale intervals, the corresponding error is:
2 x 20kg = 40kg
>. If this deviation is random, sometimes positive and sometimes negative, part of the commercial risk may balance out. But if the error repeats in one direction, for example the scale always reads 40kg lower than the true weight on each outbound truck, the business may lose 40kg of material per truck without noticing it.
| Number of weighments | Error per truck | Accumulated material loss |
| 100 trucks | 40kg | 4,000kg = 4 tons |
| 500 trucks | 40kg | 20,000kg = 20 tons |
| 1,000 trucks | 40kg | 40,000kg = 40 tons |
KALA sees a truck scale as a mass management system, not only a weighing display. The key question is not only whether the scale has passed verification, but whether it is producing repeated one-direction error that causes material loss.
III. Common causes of truck scale drift
>. Truck scale error usually does not come from one single cause. It is often the result of multiple factors accumulating during operation.
| Cause group | Practical effect |
| Local overload or long-term eccentric load on load cells | Changes the signal from individual corners and reduces repeatability. |
| Foundation settlement, mechanical binding, or incorrect anti-sway gap | Creates unwanted mechanical force and may cause directional error. |
| Moist junction box, degraded signal cable, poor grounding or lightning protection | Causes noise, signal drift, or unstable errors under different weather conditions. |
| Insufficient calibration load or incorrect corner adjustment | The scale may be correct in one load range but inaccurate in the real operating range. |
| Weighing data is not monitored | Repeated error, parameter changes, or abnormal operation can be missed. |
IV. Class II, Class III and Class III L: how should tolerance be read?
>. Scale documents may classify instruments as Class I, II, III, III L or IIII depending on the standard. For truck scales, an international reference often uses Class III L or equivalent groups for vehicle scales, axle-load scales, railway track scales, crane scales and large hopper scales.
| Step | How to check |
| 1 | Identify the accuracy class of the scale. |
| 2 | Identify the verification scale interval e. |
| 3 | Calculate the number of intervals at the test load: test load / e. |
| 4 | Look up permissible error according to accuracy class and number of intervals. |
| 5 | Distinguish acceptance tolerance and maintenance tolerance if the applicable standard defines them separately. |
Key point: tolerance depends on test load, accuracy class and verification scale interval. You cannot judge actual accuracy only by looking at the maximum capacity of the scale.
V. Why do digital load cells help manage error better?
With analog load cells, the signals from multiple load cells are usually summed in a junction box and then sent to the weighing indicator. When one corner is off, one load cell drifts, or the junction box becomes moist, troubleshooting can take time.
With digital load cells, each load cell can be individually identified and monitored. This helps technicians check corner load, detect abnormal points, monitor drift trends, identify communication faults, and support preventive maintenance.
For high-traffic truck scales, monitoring both weighing data and load cell status helps the business go beyond periodic verification and control scale performance in daily operation.
VI. KALA controls accuracy as a complete system
KALA does not treat accuracy as a load-cell-only specification. Real truck scale accuracy comes from the complete system: load cells, foundation, weighbridge structure, anti-sway system, junction box, signal cable, lightning protection, indicator, software, calibration, and operating procedure.
When selecting CASC/South-Ocean or CURIOTEC load cells for truck scales, KALA checks not only nominal capacity. Key factors include OIML R60 accuracy class, certified divisions, overload capacity, IP rating, material, mounting type, output signal, indicator compatibility, environmental conditions, and serviceability.
For better transparency, customers should request the load cell model, datasheet, label, serial number, and corresponding OIML certificate. For high-traffic truck scales, KALA often prioritizes clear technical records such as KDS/GF-1 OIML C4, CURIOTEC NDSB-A OIML C6, or CURIOTEC RPWB-A OIML C3, depending on the scale configuration and verification requirement.
| Load cell model | OIML class reference | Strength for truck scale use | Link |
| KDS/GF-1 30T CASC / South-Ocean | OIML C4 R60/2017-A-NL1-23-28 | Double-ended shear beam load cell for truck scales, rail scales and silo weighing; CASC/South-Ocean technical background, precision mechanics and stable signal performance in heavy industrial environments. | GF-1 page OIML certificate |
| NDSB-A 30T CURIOTEC Korea | OIML C6 6,000 divisions | High accuracy, IP68, 20m cable, suitable for truck scales requiring good stability, small technical display division and repeated-error control. | Vietnamese page English page |
| RPWB-A 30T CURIOTEC Korea | OIML C3 3,000 divisions | Canister column load cell, stainless steel, IP68, surge protection, suitable for truck scales, tank weighing and applications requiring high mechanical durability. | RPWB-A page OIML R60 |
Transparency note: OIML R60 is the recommendation for load cells. An OIML certificate helps confirm that the load cell type has been evaluated for metrological characteristics, but the complete truck scale must still be installed, calibrated and verified as a system.
CASC/South-Ocean has a technical foundation linked with aerospace engineering thinking: precision mechanics, load testing, signal stability and industrial durability. CURIOTEC focuses on load cells for truck scales, tank weighing and industrial force measurement applications from Korea.
Learn more about GF-1 30tf OIML C4 load cell and OIML certificate R60/2017-A-NL1-23-28.
KALA’s goal is to help customers not only pass verification, but also reduce repeated deviation, reduce scale downtime and protect profit in real operation.
VII. Link with the 3x18m 80T truck scale example
For a 3x18m 80T truck scale, if the display division is set to 5kg, the user must clearly distinguish whether 5kg is d or e. If 5kg is used as the verification scale interval e, the number of scale intervals will be:
80,000 / 5 = 16,000 scale intervals
This is a very high configuration for a normal commercial truck scale. A more practical solution is usually to use 5kg as the technical display division d, while the verification scale interval e should be defined according to the equipment file and legal verification requirement, for example 10kg or 20kg.
From a system viewpoint, KALA’s recommended configuration for a 3x18m 80T truck scale is 8 load cells x 30T, using load cells with suitable accuracy class and certificates, combined with a proper indicator, junction box, lightning protection, calibration and corner adjustment.
A good truck scale is not only a scale with a verification certificate. It is a scale that is stable, repeatable, resistant to drift over time, and able to help the business control material quantity correctly.
VIII. Useful internal references
- CURIOTEC RPWB-D digital load cell
- Load cell GF-1 30tf OIML C4
- CURIOTEC RPWB-A 30tf OIML C3
- CURIOTEC NDSB-A 30tf OIML C6
- OIML Certificate GF-1 R60/2017-A-NL1-23-28
- OIML R60-1:2021 Load Cells
- South-Ocean (CASC)
- Weighing Accuracy
KALA supports truck scale error checking, CASC/South-Ocean and CURIOTEC load cell selection, and weighing system configuration review for factories, mines, raw material yards, ports, logistics and high-traffic truck scale applications.
If you need to check a drifting truck scale, replace load cells, evaluate OIML accuracy class, or build a periodic error-monitoring procedure, contact KALA for technical support.
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