Operation of trucks is inextricably linked with the need to strictly comply with weight limits established by law. Axle load sensors It is not just an extra piece of equipment, but a vital tool for any carrier seeking to avoid multimillion-dollar fines and vehicle confiscation. Modern monitoring systems allow real-time tracking of the weight distribution along the axes and the total mass of the road train, which is critical when loading at various terminals and warehouses.
The introduction of such systems gives logistics companies transparency of processes and protects drivers from arbitrariness on weight complexes. Telematics solutions Integrate with navigation trackers and transmit data to the dispatcher server, allowing you to quickly adjust routes or download scheme. Ignoring weight control today is a direct path to financial losses and reputational risks, so understanding the principles of operation of these devices is necessary for every participant in the freight market.
Principle of operation and types of sensors
The basis of any weighting system in motion is the conversion of mechanical action into an electrical signal. Tensometer sensors (tensor sensors) are the most common type of sensors used in this field. The principle of their operation is based on a change in the electrical resistance of the conductor during its deformation: when the axis of the car presses on the spring or air suspension cushion, the sensitive element bends, and the system records the change in voltage, converting it into kilograms or tons.
There are several design versions of sensors, the choice of which depends on the type of suspension of the truck. For vehicles with air suspension Pressure sensors are often used that read readings from the pneumosystem, but they are less accurate at dynamic load compared to strain gauge analogues. Mechanical systems installed on spring suspensions require more complex installation, since it is necessary to ensure direct contact of the sensor with the deformable element without violating the regular geometry of the chassis.
⚠️ Note: Using cheap analog sensors without digital signal processing can lead to errors of up to 15-20% when driving on uneven road surfaces, making them unsuitable for legally significant weighing.
Modern digital systems are equipped with built-in microprocessors that filter noise and vibrations that occur when moving. The critical parameter is the degree of protection IP67 or IP68.As the equipment is constantly exposed to moisture, reagents and dust. The reliability of the insulation of the compounds determines the durability of the entire system, especially in harsh climatic conditions of operation.
Legal aspects and fines for overload
Weight control is particularly important in light of the tightening of the administrative code. Axis overload or tsng weight of the car is the basis for imposing fines, the amount of which is hundreds of thousands of rubles. The legislation clearly regulates the maximum permissible loads, and the presence of an on-board weighing system is often considered as proof of the carrier's good faith, although it does not completely relieve liability for obvious violations.
Control systems help to avoid situations when the driver, not knowing the exact weight of the cargo, goes to the line with excess of norms. Automatic Weight Control (AWC) It records violations on the roads with high accuracy, and it is difficult to dispute such data. Therefore, the presence of own data from load sensors allows you to conduct an independent examination and, in some cases, prove the serviceability of the cargo or the error of stationary scales.
- 🚛 Penalties for congestion can exceed the cost of the transportation itself several times.
- ⚖️ Data from certified sensors can be used in court as evidence.
- 📉 Monitoring systems help optimize logistics and eliminate downtime at weighing.
It is important to understand the difference between static and dynamic weighting. Static is carried out on a stationary car and is the reference, while dynamic (in motion) has an allowable error. Sizing The onboard systems should be carried out regularly to minimize discrepancies with the reference weights.
Keep a log of sensor calibration and save the acts of weighing at the terminals - this will help protect your interests in controversial situations with traffic police.
Installation of equipment: step-by-step instructions
Installation of load sensors is a technically complex process that requires qualification and a special tool. The first step is always to diagnose the suspension and select the installation points. For spring suspensions, sensors are mounted between the frame and the stepladder of the spring or crash into the spring itself, which requires accuracy so as not to disturb the integrity of the metal. On air suspension, pressure sensors crash into the highway between the pillow and the floor level crane.
The construction of cable lines requires special attention. All wires must be protected by corrugated and securely secured by clamps to prevent rubbing against moving parts of the chassis. Sealing compounds It is performed using specialized shrink tubes with adhesive layer. Errors in the installation phase, such as poor contact or inadequate moisture protection, are the main cause of system failures in the first year of operation.
☑️ Checklist before installation
After physical installation, it is necessary to connect the system to the on-board network of the car and the satellite monitoring unit. Often, you need to set the thresholds at which the system will signal the driver. Data processing unit It is usually installed in the cabin where access is provided for maintenance and visual monitoring of indicators.
⚠️ Warning: When drilling frames or springs, strictly observe the technology so as not to create stress concentration points that can lead to the destruction of the element under load.
Calibration and system setting
Proper calibration is the key to the accuracy of the readings. The adjustment process begins with the introduction of the container (self weight) of the car. For this purpose, the vehicle must be fully refueled, equipped with a driver and not loaded. Zero point. It is fixed in the system, and all subsequent measurements are relative to this value. Errors at this stage will result in a systematic distortion of all future weighing results.
The next step is calibration for reference cargo. It is necessary to load the car with a known weight (for example, by passing through a certified scale) and enter this data into the system. Sensor software, such as Wabco Optilev or analogues from other manufacturers, allows you to adjust the signal gain coefficients. The process may require multiple iterations of loading and unloading to achieve high accuracy.
| Parameter | Description | Impact on accuracy |
|---|---|---|
| Temperature compensation | Correction of readings when temperature changes | High (metal changes properties) |
| Vibration filtering | Smoothing of surges in motion | Critical for dynamic weighing |
| Linearization | Calculating the signal dependence on weight | Provides accuracy throughout the range |
This requires periodic recalibration of the system, especially after major chassis repairs. Regular verification This allows to maintain the accuracy of measurements within the declared manufacturer 3-5%.
What affects the drift of testimony?
The drift of indications (zero change) is often caused by thermal expansion of the metal frame or spring fatigue. Also, the cause may be the oxidation of contacts in the sensor connectors. Regularly checking the “zero” on an empty car helps to notice the problem in time.
Integration with monitoring systems and GLONASS
Modern load sensors rarely operate autonomously. Their main value is realized when integrated with telematics platforms and satellite monitoring systems. Data transmission protocols, such as EGTS Proprietary formats of tracker manufacturers allow you to transfer real-time weight data to the company's server. The dispatcher sees not only the location of the machine, but also its loading, which prevents attempts to steal cargo or unauthorized dispensing of fuel (indirectly, through weight change).
Integration allows you to automate the workflow. Weight data may be automatically inserted into travel lists and consignment notes. This eliminates the human factor and manipulation of numbers. APIs Most platforms allow you to embed weight data into the corporate ERP systems of logistics companies.
- 📡 The data is transmitted via GSM/GPRS or satellite communications.
- 🖥️ The controller sees disturbing events (overload) instantly on the map.
- 📊 Formation of fleet load reports for efficiency analysis.
When setting up integration, it is important to correctly match sensor identifiers with the car’s axes in monitoring software. An error in the mapping (for example, when the weight of the rear cart is assigned to the front axle) will make the data useless. Tracker configuration It should be performed by a qualified specialist who knows the specifics of working with the CAN bus of the car.
⚠️ Note: When connecting to a CAN bus, use only certified adapters to avoid conflicts in the onboard network and possible failure of electronic control units (ECUs).
Frequent malfunctions and diagnostic methods
Despite its high reliability, weight control systems are subject to aggressive environments. The most common problem is a cliff or short circuit in cable tracks due to vibration and moisture. Diagnostics It begins with a visual inspection of the integrity of the wires and connectors. The multimeter allows you to check the resistance of the sensors: it must correspond to passport values (usually 350 or 700 ohms per bridge).
If the system shows unstable values or "floats" zero, the cause may be a violation of the geometry of the sensor installation or damage to the strain cell. In the case of pneumatics, condensation in airways becomes a frequent problem, which gets into the pressure sensor. Regular purging of the system and installing moisture separators help to avoid this.
Software failures of the processing unit are also possible, especially when voltage surges in the onboard network. System restart or reset to factory settings often help restore performance. If software methods do not help, a faulty component must be replaced.
90% of load sensor malfunctions are due to mechanical damage to the wiring or oxidation of the contacts, not to the failure of the sensors themselves.
How often should load sensors be changed?
The service life of high-quality strain gauges is 5-7 years or more. However, in conditions of intensive operation and aggressive environment, it is recommended to carry out their full diagnosis annually, and replace them when the error exceeds the permissible limits that cannot be eliminated by calibration.
Can I install the sensors myself?
Theoretically, it is possible if you have the skills to work with electricity and welding. However, to obtain the legal significance of the indications and preserve the warranty for the car, it is better to contact a specialized service that will issue the installation passport and calibration factors.
Does the installation of sensors affect the warranty of the car?
Interference with the design of the frame or springs can cause a denial of warranty on these units. The use of overhead sensors and connection through standard connectors minimizes risks. Always agree the installation with the dealer.
What if the sensor shows different weights?
A comparative analysis is needed. If the difference is between 3 and 5 percent, this is an acceptable margin of error. If more, recalibration is required on certified weights with reference load. Also check the tire pressure that affects the weight distribution.