Modern cargo transportation cannot be imagined without strict control of the weight parameters of the vehicle. Installation of axle load sensors becomes not just a desire of the fleet owner, but a vital necessity for protection from huge fines from weight control. The integration of such systems allows the driver to see in real time the actual load on each group of wheels, preventing overload and damage to the chassis.
The installation process requires deep knowledge in the field of auto electrical and suspension mechanics, since the measurement error depends on the accuracy of the installation. Installation errors can lead to incorrect data, which will ultimately cause financial losses or accidents on the road. In this article we will analyze in detail all the stages of implementing a weighing system, choosing equipment and the subtleties of calibration.
Before starting work, it is necessary to decide on the type of sensors and where they will be integrated into the existing design of the truck or semi-trailer. The market offers many solutions, from simple analog systems to complex digital systems with GPS tracking. Choosing the right equipment initially will save time and resources in the future.
Selecting the type of sensors and weighing equipment
The first step to a successful upgrade is selecting the right equipment. Today the most common strain gauges, which convert mechanical deformation into an electrical signal. They are divided into several types depending on the design of the vehicle suspension: for pneumatic, spring and hydraulic systems.
For trucks with air suspension, pressure sensors are most often used, embedded in the air supply line to the cushions. Their work is based on the direct dependence of air pressure on the mass of the load. In the case of springs, applied strain gauges or systems are used that measure the deflection of the spring relative to the frame. Digital systems are characterized by higher accuracy and the ability to transfer data to a remote server.
⚠️ Attention: Using cheap analog sensors without temperature compensation can lead to errors of up to 10-15% when weather conditions change. For commercial use, choose equipment with a protection class of at least IP67.
When choosing a kit, you should pay attention to the presence of a certified display in the driver’s cabin. The screen should be readable in bright sunlight and have an intuitive interface. Some modern models allow you to output data to the driver’s smartphone via Bluetooth, which adds convenience to use.
Preparatory work and diagnostics of electrical wiring
High quality installation of sensors impossible without careful preparation. Before starting work, the vehicle must be driven onto a level area, and the cargo must be completely unloaded for calibration “to zero”. It is necessary to visually inspect the condition of the frame, springs and pneumatic elements for damage that could distort the scale readings.
Particular attention is paid to electrical wiring. You will need to find a 12V or 24V power source (depending on the vehicle's on-board network), which only works when the ignition is on. This will prevent the batteries from draining while parked. It is recommended to use corrugated cables and clamps for laying wires, protecting the cables from vibration, dirt and mechanical damage.
During the preparation process, it often becomes necessary to drill the frame or body elements. It is strictly forbidden to drill into frame side members in areas of maximum stress., as this can lead to cracks and structural failure. All holes after laying wires must be treated with anticorrosive and plugged with rubber bushings.
☑️ Preparation for installation
Technology for mounting sensors on various types of suspensions
The installation process directly depends on the design of the chassis. For air suspension, installation is usually the least labor intensive. The pressure sensor fits into the tube between the control valve and the air spring. It is important to ensure tight connections using quality thread sealant or fittings.
On leaf spring suspensions, installation is more complicated and requires attaching strain gauges directly to the spring or frame above it. Positioning accuracy is critical here: the sensor must read the compression force, but not interfere with the suspension during compression and rebound strokes. Special brackets that come with the equipment are often used.
- 🔧 For mounting on springs, use only high-strength bolts of class 8.8 and higher.
- 🔧 Lay the wires from the sensors to the control unit away from heat sources and moving parts.
- 🔧 When installing on hydraulics, make sure that the pressure sensor is designed for the operating pressure of the system (usually up to 300 bar).
After physical installation of all elements, it is necessary to check the reliability of the fastenings. Vibration can cause loose bolts to loosen, causing signal loss or damage to the sensor. It is recommended to use thread locker for all connections.
Connecting the control unit and display
The central element of the system is the control unit (CU), which processes signals from sensors. It should be placed in a protected location, preferably inside the cab or in a sealed box on the frame. The main requirement is the absence of direct contact with water and excessive heating.
Connecting the display in the cockpit requires care. It is best to conduct wiring along the standard vehicle harnesses, using existing technological holes. To connect wires, use soldering or special crimp sleeves, avoiding simple twists, which oxidize and lose contact.
Connection diagram (approximate):Red wire -> Battery positive (via 5A fuse)
Black wire -> Ground (body)
Yellow wire -> Ignition switch (ACC)
Blue/Green -> Signal from sensors
⚠️ Attention: Before connecting the power, be sure to “ring” all wires with a multimeter for short circuits. An error in polarity can instantly destroy an expensive control unit.
Some advanced systems allow you to connect additional modules, such as GPS trackers or external antennas. This allows the dispatcher to see the weight of the cargo in real time on the map. Integration of such functions requires the configuration of appropriate data transfer protocols.
What should I do if the display does not turn on?
If the display does not respond after installation, check the fuse in the power supply. If it is intact, measure the voltage at the input to the control unit. Often the problem lies in poor ground contact or a wire break where the corrugation is bent. Also make sure the ignition switch is sending a signal to the ACC wire.
System calibration and weighing accuracy adjustment
The most important stage is calibration. Without it, sensor readings will be random. The procedure is carried out on certified vehicle scales. The system is first calibrated empty, then weighed with a known load to construct a calibration curve.
The setup process usually looks like this: drive the car onto the scales, record the scale readings, then enter these values into the control unit menu. The system remembers the correspondence between pressure or deformation and real mass. For high accuracy, it is recommended to do several calibration points (for example, 0%, 50% and 100% load).
| Parameter | Description | Recommended value |
|---|---|---|
| Measurement accuracy | System error | ± 3-5% (depending on model) |
| Temperature range | Operating temperatures | -40°C to +85°C |
| Polling frequency | Data Update | 1 time per second |
| Supply voltage | On-board network | 12V/24V |
After the initial calibration, test runs must be carried out. Load the vehicle with different weights and compare the on-board system readings with reference scales. If the error is outside the permissible limits, the calibration procedure is repeated. Regular verification It is recommended at least once a year.
When calibrating, take into account the weight of the fuel in the tanks and the driver. For maximum accuracy, perform adjustments with a full tank so that changes in fuel level do not affect the sensor readings.
Typical installation errors and their elimination
Even experienced craftsmen sometimes make mistakes that ruin all the work. One of the most common problems is the incorrect choice of location for installing the sensor on the spring. If you attach it too close to the edge or center, the readings will be incorrect due to the uneven distribution of metal stress.
Another common mistake is ignoring the quality of connection insulation. Trucks operate in conditions of high humidity, dust and chemicals on the roads. Poor insulation leads to oxidation of contacts, the appearance of “floating” readings or complete system failure.
- ⚡ Lack of signal damping: without setting signal filtering, the readings on the screen will jump when driving over uneven surfaces.
- ⚡ Using too long wires without shielding: may lead to interference from the generator or walkie-talkie.
- ⚡ Ignoring the threshold setting: the system may not signal an overload if the threshold is set incorrectly.
To eliminate problems with a “noisy” signal in the settings of the control unit, the smoothing coefficient should be increased. This will make the readings more stable, although it will add a slight delay in updating the data. In difficult cases, it may be necessary to install an additional shielding casing for the wiring.
⚠️ Attention: If after installation the system shows negative weight or incorrect values even after calibration, check the polarity of the load cells. Confused "+" and "-" are a common cause of incorrect operation.
Legal aspects and data use
It is important to understand that on-board weighing systems are for reference only. In the event of a dispute with traffic police officers or weight control, the readings of certified stationary or mobile scales take precedence. However, data from sensors can serve as evidence of the driver’s integrity in court.
Some fleets integrate weighing systems with tachographs and monitoring systems. This allows you to automatically record facts of overload and identify the driver who committed the violation. Such measures discipline staff and reduce risks for the company.
An on-board weighing system is a preventative control tool that helps avoid fines and breakdowns, but does not legally replace government scales.
Legislation is constantly changing, and the requirements for the accuracy of weight control are becoming more stringent. Installing quality equipment is an investment in the safety and legal protection of your business. In the future, it is possible to introduce mandatory telemetry of weight parameters for trucks of a certain category.
FAQ: Frequently asked questions
Is it possible to install sensors yourself without special service?
Theoretically, yes, if you have electrical skills and an understanding of suspension design. However, calibration will still require a visit to an accurate scale. Installation errors may result in damage to the chassis.
Does installing sensors affect the vehicle warranty?
Tampering with the standard electrical wiring and drilling the frame may result in denial of warranty service from an authorized dealer. It is recommended to clarify this issue before starting work.
How often should the system be calibrated?
Manufacturers recommend calibration at least once a year or after replacing suspension elements (springs, cushions). Calibration is also needed if you notice a significant discrepancy in readings.
Does the system operate at sub-zero temperatures?
High-quality industrial sensors are designed to operate at temperatures down to -40°C and below. However, in severe frosts, the pneumatic system may be delayed, which should be taken into account when interpreting the data.