A standard gas circuit layout is only the basis. Whether Trailer ABS is good or not depends largely on the system itself. So what problems are prone to occur in vehicles equipped with these inferior ABS assemblies?
1. ABS connection line is broken, wheel speed and control signal are lost
During the inspection process, we found that the ABS connection line of this trailer was broken in many places. The external protective cover was not found to be worn or scratched. It was broken from the inside. It was initially determined to be an inferior ABS connection line. The line core material is made of inferior materials. Metal fatigue and rust are very likely to occur during use, which leads to the line breaking from the inside, making it very difficult to inspect. Many car owners give up inspections because they cannot find the fault point after multiple repairs. If the detection line is broken, the wheel speed signal of ABS cannot be transmitted to the computer, and the computer cannot let the solenoid valve take braking measures according to the wheel speed signal. If the control line is broken, the braking command issued by the ABS host cannot be transmitted to the solenoid valve, and the solenoid valve cannot execute the braking command. In other words, no matter whether the control line or the signal line is broken, the ABS of the wheel position will become a decoration as long as it is broken.
2. Oxidation corrosion of inferior connectors cannot transmit signals normally
During the inspection process, we found that many connectors had oxidation corrosion. The contacts of inferior connectors were copper-plated, which was very easy to corrode when exposed to water during use. The contacts of genuine connectors are plated with silver oxide, which has better corrosion resistance and conductivity than copper-plated connectors.
The sealing performance of inferior connectors is basically invalid. It can be seen that a lot of mud has entered the top of the sealing ring in the picture, and there are no friction marks on the sealing ring during the plug-in and unplug process, which is obviously invalid. The sealing ring of the genuine connector is made of high-quality rubber. We can see that the rubber ring is quite thick and elastic. During the installation process, after the connector is plugged in and then unplugged, the rubber ring has very obvious friction marks, which proves that the sealing performance of the genuine connector is no problem.
3. Trailer ABS gear ring deformation cannot collect the correct signal
The installation of the gear ring of the car we encountered also had problems. The gear ring was not installed by heating according to regulations during installation, but was hit hard with a heavy object, resulting in the deformation of the gear ring. After the gear ring is deformed, the wheel speed sensor cannot correctly collect the wheel speed signal, and the following two situations may occur:
- The wheel speed sensor sends the collected error signal to the ABS host, and the ABS host issues an erroneous execution command to the wheel position after analysis.
- After the ABS host receives the signal and finds that the wheel speed data is abnormal, the system will default to the abnormal signal of the wheel position and will not send any execution command to it, which means that the ABS of the wheel position is ineffective.
When installing, the gear ring should be fully heated to about 180℃-200℃ and maintained at a temperature of 5-10 minutes, and then the gear ring and the wheel hub should be assembled. It is best to heat the gear ring to the point where it can be directly placed in the wheel hub flange slot and can be rotated, so as to ensure that the gear ring is directly installed in place without the need to use external force to correct the position of the gear ring. It is forbidden to impact the gear ring with metal objects to avoid damage and deformation of the gear ring, which will affect the accuracy of the sensor signal.
4. The wheel speed sensor is not installed properly and the distance is too large
The distance between the ABS wheel speed sensor and the gear ring should be kept within 0.3mm-0.5mm. Too far will affect the collection of wheel speed signals and the accuracy of wheel speed data. Whether the ABS wheel speed sensor is installed properly will directly affect the use effect of ABS.
The sensor installation method is to insert the wheel speed sensor into the clamping bushing, install it into the clamping body, and install it on the sensor bracket of the axle. Fuhua axle needs to use welding to fix the sensor bracket on the axle, while BPW axle reserves the installation position of the sensor bracket, and the sensor support can be directly fixed with screws. After fixing the sensor clamping body, the sensor and the gear ring are vertically aligned and keep a certain distance.
5. The brake light power supply is unreliable and the safety hazard is great
Now many trailer manufacturers directly connect the ABS power supply line to the brake light in order to save costs, but the ABS system will complete the self-check process in the initial stage of power-on, which usually takes 3-5 seconds. Since the brake light circuit is only powered on when braking, and ABS has a self-checking time of 3 to 5 seconds each time the circuit is connected.
This results in the ABS starting to connect the circuit and start self-checking when the driver steps on the brake pedal, missing the best time to brake. If the driver takes the brake pedal, the ABS system will repeatedly connect the power for self-checking. Frequent power-on self-checking may also cause the ABS computer box to burn, and the ABS system has no effect at all during frequent power-on self-checking.
Because there are hidden dangers in the method of drawing power from the ABS brake light, the new regulations require that the ABS power supply system of the semi-trailer must be powered by an ISO7638 independent socket. After the ABS is independently powered by ISO7638, after the vehicle is started, the ABS system is powered on for self-checking, and then it is always on standby to monitor the vehicle dynamics in real time. When the driver steps on the brake pedal, the ABS can participate in the work to ensure driving safety at all times.
6. Trailer ABS sensor layout is unreasonable
The layout of trailer ABS also has a great impact on the braking effect. If the ABS sensor of trailer 4S/2M adopts the 2/3 bridge layout method, that is, the sensor and solenoid valve are arranged on the second and third bridges of the trailer. This layout is very unreasonable. Due to the height of the saddle, the first bridge of the trailer is often subjected to the least force and the friction with the ground is also the smallest, and the first bridge wheel is prone to lock when braking.
Since the first bridge is subjected to the least force and is prone to lock, what will happen if the sensor is arranged in 1/2 bridge? The answer is also no. Since the load of domestic semi-trailers is much higher than that of European and American countries, the forward shift of the center of gravity during braking causes the bowing phenomenon to be more serious. Braking under heavy load will move the center of gravity forward, the body sinks forward, the force on the third bridge is reduced, and the friction between the tires of the third bridge and the ground is greatly reduced, which is very easy to lock.
We know that the first bridge is prone to lock when the vehicle is empty, and the third bridge is prone to lock when the vehicle is heavy. Only the second bridge is the most evenly stressed. Therefore, the ABS sensor of trailer 4S/2M adopts the 1/3 bridge layout method to control the 1/3 bridge that is most likely to lock, so as to achieve the best braking effect.
What kind of layout method should be adopted for the ABS sensor of trailer 4S/2M to achieve the best braking effect.
Common reasons for the Trailer ABS light on a Semi-trailer.
The ABS light on a semi-trailer usually indicates that the vehicle’s anti-lock braking system is faulty. The following are some common reasons that may cause the ABS light to light up:
Speed sensor failure: The sensing part of the ABS speed sensor is covered by impurities such as dirt and mud, which affects the sensor’s sensing of the corresponding speed signal, making it impossible for the ABS computer to determine the speed, the slip rate of the wheel, and thus unable to issue corresponding action instructions to adjust the brakes
System line connection problem: Poor contact of the ABS relay causes poor signal and causes system failure. The most common cause of failure is that the speed sensor wire plug is loose.
The system power supply voltage of the ABS is too low: if the wire head is not in contact or the grounding is poor, the ABS warning light will light up intermittently, and the ABS warning light will go out when accelerating. When using a variety of vehicle electrical appliances, the battery voltage drops below 10.5v, the engine speed increases, the voltage increases, and the ABS indicator light goes out.
ABS or ABS/ASR computer failure: The ABS warning light stays on after the engine is started and does not go out until the engine IGFF: The ABS hydraulic valve body grounding circuit has poor contact; The ABS hydraulic valve body wire connector has poor contact; The ABS computer fails.
Incorrect tire specifications or incorrect rim specifications: The ABS warning light comes on when driving at high speed: When driving at high speed, the ABS computer calculates the speed signal and the rear wheel speed is too different from the front wheel speed; incorrect tire specifications or incorrect rim specifications.
Poor internal contact of the brake light: Improper adjustment of the brake light switch and poor internal contact of the brake light. This will cause the ABS warning light to light up intermittently.
ABS pump and pressure regulating solenoid valve failure: Due to loose connections between ABS circuits, internal failures of the ABS pump, etc., the ABS light will also light up. This failure requires a comprehensive inspection.
When the ABS indicator light is on, be sure to pay attention and solve it in time, because it is related to the braking performance in an emergency. Do not ignore it, ensuring driving safety is the top priority.