Analysis of wheel balance and four wheel positioning technology

Category:Brake system foundation - Date:2015-10-29

wheel balance and positioning, as a routine inspection item in the maintenance, the wheel balance instrument, the four wheel locator and some auxiliary equipment should be used for the necessary inspection. When vehicle is running, steering wheel jitter, braking deviation and excessive or insufficient steering are needed. Based on the main line of vehicle entry and maintenance process, the equipment and related inspection technology for wheel balance and location are analyzed.

1 confirmed the symptoms of the malfunction through a question and a road test

the interrogation is very important. The driver provides a comprehensive and real fault time, condition, cause and the accompanying malfunction, which can provide a lot of important reference for the maintenance work. The maintenance personnel should understand the situation scientifically and reasonably, and also be good at communicating with drivers. The following questions should be asked, such as the time of the first failure, and the changes of the performance, the history of maintenance and the specific conditions (such as the replacement of the parts, etc.). The information obtained in inquiry is also coarse and refined, and reasoning with its key points often leads us to find out the correct way of eliminating trouble.

road test can confirm the customer's complaint and further confirm the fault symptoms. The road test before the four wheel positioning and dynamic balance can provide the maintenance clues for the wear of the control arm shaft sleeve or the support bearing, the strength attenuation of the support damper or the damper, the loosening of the installation of the steering gear, the loosening of the wheel bearings, and the failure of the tires. If possible, it's best to have a road trial with the driver. If there are obvious faults before the location, the driver's attention is noticed. These links are very important. For example, the vibration of steering wheel and vehicle floor is often caused by static imbalance of front tire or radial vibration of tire. The maintenance personnel should try to make a preliminary analysis of the possible causes of the failure in the process of road trial, and determine the correct direction of maintenance.

necessary inspection for.2 before maintenance

check carefully before moving balance or four wheel positioning, and find out the reasons that affect the four wheel alignment and dynamic balance. The following parts are generally required to be checked.

(1) test fetal pressure

only when the tire pressure is kept at the best value, tire life, vehicle power and fuel consumption can be in the best condition. When the performance and quality of pointer tire pressure gauge can't satisfy people's needs gradually, electronic tire pressure gauge arises at the historic moment. When the electronic tire pressure meter is used, pressure gauge gas nozzle is used to press the tire valve valve, so that the butt between the gas nozzle and the valve is well sealed, and the leakage sound can not be produced. The electronic switch will automatically turn on, and the tire pressure value is locked and displayed on the screen. After the pressure gauge leaves the tire nozzle, the tire pressure will continue to display 6~12 s on the monitor, then the gauge will automatically return to zero and the measurement will be finished. Compared with the existing pointer type tire pressure gauge in the domestic market, the electronic tire pressure is high precision, beautiful and practical, and easy to carry. It has the following advantages: 1. When inflation, ensure high accuracy of air pressure and make multiple wheels balance.
The operation is fast and convenient. (3) to keep the tire pressure and the balance of tire pressure, it is helpful to prolong the service life of the tire, improve the safety of the driving, enhance the comfort of the ride, and carry out the wheel dynamic balance and four wheel positioning test during the maintenance of the vehicle.

(2) check the tread

the tread depth scale visual inspection can provide more accurate indication of the tread state, and the tread depth ruler can be placed in the tread groove to measure the tire wear. The operation of these depth rulers is similar to that of the pencil type tire pressure gauge, and the way of reading data is also the same.

(3) check chassis and suspension parts.

visual inspection is a very important link. In maintenance, we need to use lifting machine to check the following parts: (1) hub and bearing. Wheel hub and bearing are the potential causes of vibration. Excessive bearing wear will cause vibration and pendulum phenomenon. The wheel and hub flange is rusty or with foreign objects, and it can also cause excessive vibration. If the wheel hub bolt installation holes are not properly positioned, the wheel hub double head bolt vibration pendulum may exceed the limit. The examination of the ball head. Check whether there is a crack or a crack in the ball seal. If part of the oil seal is difficult to observe, you can use your fingers to touch the oil seal with incision or cracks. If there is a lot of grease, it will prove that the oil seal is cracked. If a notch or crack is found, the ball head should be replaced. 3. Turn to the cross bar. The steering tie rod must have zero degree free clearance, but it can still allow the suspension to rotate and move. The wear of steering tie rod will lead to too much steering query. The rack and pinion steering mechanism and the steering tie bar on the standard recirculating ball system are checked in the same way. (4) shock absorber. A comprehensive check is made for mechanical damage or liquid leakage of shock absorber. If there is mechanical damage or excessive liquid leakage, the shock absorber should be replaced. If the absorber appears to be in good condition, it can detect the shock absorber. It is common practice to test the workbench, some of the shock absorbers need to remove the lower bracket from the vehicle during the inspection, while the upper bracket is still connected to the vehicle and then inspected.

3 uses the wheel balance to move the balance

When a vehicle runs at high speed, the steering wheel jitter, or a certain rhythmic abnormal sound of the wheel, may be the balance of the wheel. In addition, the wheel must be balanced when the tire, the hub or the wheel have been repaired, the wheel has a big impact and the bump is caused by the loss of the balance block. The wheel balance instrument is used to carry out dynamic balancing equipment. With the improvement of the R & D level of the steam protection equipment, some high-end equipment not only carry out the dynamic balance of the wheel, but also have the vibration control system and the road condition simulation test system. This kind of equipment generally has a road condition simulation drum, which can bear the quality of the wheel, truly reflect the imbalance of the tire during the driving process, and give the revised value recommended by the system according to the needs, avoiding the unnecessary trouble in many maintenance diagnosis processes.

what should be noticed is that when the unbalanced volume exceeds the maximum counterweight, more than 2 counterweights can be used side-by-side in the process of dynamic balancing. But at this time to pay attention to more weight occupy a large fan, the effective mass is less than the actual quality. In addition, dynamic balancing for high speed vehicle wheels, such as racing cars, requires checking and proofreading. That is to say, after balancing the wheels with ordinary wheel balancer, it is best to confirm with the car wheel balancer.

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