Teach you how to choose a four-wheel alignment device from four aspects

At present, there are mainly two types of four-wheel alignment instruments on the market: conventional and advanced. The conventional two-wheel alignment has 2D four-wheel alignment and the more advanced 3D four-wheel alignment.

Types of four-wheel alignment

There are several types of four-wheel alignment devices, such as toe ruler, optical level locator, cable locator, CCD locator, laser locator, and 3D image locator. Among them, 3D, CCD and laser products are the three mainstream products on the market. 3D products are the most advanced four-wheel positioning on the market. The measurement method is advanced and the measurement time is only one-fifth of the traditional locator. It has gradually matured. .

Beijing exhibition, major four-wheel alignment manufacturers have shown V3D four-wheel alignment products, and V3D has become the biggest highlight of the exhibition. The major four-wheel positioning manufacturers have launched their own V3D products one after another, and the V3D market war is bound to begin immediately. The V3D measurement capability surpasses the optical sensor in an all-round way. In addition to calculating the four-wheel positioning angle, it can also calculate the wheelbase, wheel difference, wheelbase, axle difference, friction radius, steering trajectory and other functions. Moreover, the optical sensor has many after-sales and the operation is cumbersome.

The emergence of V3D is very likely to replace the market segment of medium and high-end optical machines. Four-wheel alignment is based on the four-wheel parameters of the vehicle, and it is adjusted to ensure good driving performance and certain reliability of the vehicle. The installation of the steering wheel, the steering knuckle and the front axle of the car has a certain relative position. This installation with a certain relative position is called steering wheel positioning, also known as front wheel positioning. The front wheel positioning includes four contents: kingpin caster (angle), kingpin inclination (angle), front wheel camber (angle) and front wheel toe. This is for the two steering front wheels, and for the two rear wheels, there is also the relative position of the installation with the rear axle, which is called rear wheel positioning. Rear wheel positioning includes wheel camber (angle) and toe-by-wheel toe. In this way, the front wheel alignment and the rear wheel alignment are collectively called four-wheel alignment.

The installation between the steering wheel, the steering knuckle and the front axle of the car has a certain relative position. This kind of installation with a certain relative position is called steering wheel alignment, also known as front wheel alignment. The front wheel positioning includes four contents: kingpin caster (angle), kingpin inclination (angle), front wheel camber (angle) and front wheel toe.

The role of the car in four-wheel alignment

1. Increase driving safety;

2. Reduce tire wear;

3. Keep the steering wheel upright when driving straight, and keep driving straight;

4. The steering wheel automatically returns to the right after steering; l Increases the sense of driving control;

5. Reduce combustion consumption;

6. Reduce the loss of suspension parts.

When the vehicle is used for a long time, the user finds that the direction of the vehicle is heavy, trembling, off-track, incorrect, out of position, or unilateral wear of the tire, wavy wear, block wear, eccentric wear and other abnormal wear, as well as abnormal wear when the user is driving. When the phenomenon of floating, bumping, swaying, etc. occurs, you should consider checking the wheel alignment value to see if there is too much deviation and repair it in time. The front wheel positioning includes four contents: kingpin caster angle, kingpin inclination angle, front wheel camber angle and front wheel toe. Rear wheel alignment includes wheel camber and toe-by-wheel toe. In this way, the front wheel alignment and the rear wheel alignment are collectively called wheel alignment, which is often referred to as four-wheel alignment. The role of wheel alignment is to keep the car stable in a straight line and steer lightly, and to reduce the wear of the tires and steering parts of the car during driving.

Kingpin angle

Looking at the wheel from the side, the kingpin (the center of rotation when the wheel turns) tilts backward, which is called the caster angle. After setting the caster angle, there is a distance between the ground point of the center line of the kingpin and the ground projection point of the wheel center (called the kingpin pitch shift, which is the same as the principle of the front wheel fork beam of a bicycle tilting backward). The grounding point of the wheel is located at the rear end of the extension line of the steering kingpin, and the wheel is pulled back by the rolling resistance during driving, so that the direction of the wheel is naturally oriented toward the direction of travel. Setting a large caster angle can improve the straight line.

King pin inclination angle

When the tire is viewed from the front and rear direction of the car, the kingpin axis is inclined to the inside of the car body. This angle is called the kingpin inclination angle. When the wheel rotates centered on the kingpin, the lowest point of the wheel will sink below the road surface, but in fact, the lower edge of the wheel cannot sink below the road surface. Instead, the steering wheel and the entire front of the car are raised to a corresponding height. In this way, the gravity of the car itself has the effect of returning the steering wheel to the original intermediate position, so the steering wheel is easy to reset. In addition, the inclination angle of the kingpin also reduces the distance from the intersection of the axis of the kingpin and the road to the intersection of the center plane of the wheel and the ground, thereby reducing the driver’s force on the steering wheel during steering, making the steering easier and reducing The impact force transmitted from the steering wheel to the steering wheel. However, the inclination angle of the kingpin should not be too large, otherwise it will accelerate the wear of the tire.

front wheel camber

When the wheel is viewed from the front and rear direction, the tire is not installed vertically, but slightly tilted and opened in a “eight” shape, which is called negative camber, and when it is opened in the opposite direction, it is called positive camber. In the heyday of using diagonal tires, the camber angle was set to be relatively large because the tires were inclined to touch the ground to facilitate the operation of the steering wheel. Cars generally set the camber angle to be very small, close to vertical. Flat radial tires used in automobiles continue to spread. Due to the characteristics of radial tires (the tire pattern is rigid and the tread is wide), setting a large camber angle will cause the tire to wear out and reduce tire friction. Also, due to the continuous use of the power steering mechanism, the camber angle has been continuously reduced. Nevertheless, setting a small camber angle can apply appropriate lateral thrust to the wheel bearings on the axle.

front wheel toe

The toes point inward, the so-called “inner stilt foot” means that the left and right front wheels are inward respectively. The purpose of adopting this structure is to correct the outward rotation of the wheel caused by the aforementioned front wheel camber angle. As mentioned earlier, due to the camber, steering wheel operation becomes easy. On the other hand, due to the tilt of the wheels, the left and right front wheels rotate to the outside respectively. To correct this problem, if the left and right wheels have an inward angle, the positive and negative values ​​are zero, and the left and right wheels can keep straight and reduce tire wear. The above four positioning values ​​are indicators of front wheel positioning. The rear wheel positioning value is similar to the front wheel positioning value, but the rear wheel positioning of most cars is not adjustable.

What is the need for a four-wheel alignment device

If the data suggested in your vehicle manual is the same as the data in the four-wheel alignment computer, it is universal. Generally speaking, four-wheel alignment is required in the following situations. 1. After replacing a new tire or repairing in a collision accident; 2. Unilateral wear of the front and rear tires; 3. The steering wheel is too heavy or floating and trembling when driving; 4. When driving straight, the car runs to the left or right; 5. Although there is no above However, for maintenance purposes, it is recommended that the new car be driven for 3 months and then once every six months or 10,000 kilometers.

The benefits of four-wheel alignment

Four-wheel alignment is one of the necessary tasks for vehicle maintenance. Unless there are obvious problems related to it before the four-wheel alignment, such as poor straight running stability, etc., you can feel it immediately after the four-wheel alignment, otherwise it is difficult for you to judge whether it is good or not. Due to the uneven quality of the auto repair industry, the quality of maintenance varies greatly, so it is recommended that you try to maintain the quality of the four-wheel alignment and ensure the safety of driving. Its benefits are: 1. Enhance driving comfort; 2. Reduce gasoline consumption; 3. Increase tire service life 4. Ensure straight-line stability of the vehicle; 5. Reduce the wear of chassis suspension parts; 6. Enhance driving safety

Misunderstanding

Misunderstanding 1: Think that the four-wheel alignment is to adjust the toe of the front wheels “four-wheel alignment”

As the name implies, it is necessary to consider the positioning state of the four wheels of the car. Toe is an angle concept, which is technically called toe angle. In the past, when the maintenance master in the repair shop did not have technical data and wheel alignment equipment, he could only use his experience to measure the difference between the front and rear ends of the two front wheel diameters with a meter. It is the concept of length. In fact, the front wheels not only have toe angles, but also camber, kingpin casters, and kingpin inclination angles; the rear wheels also have toe angles, as well as main positioning angles such as wheel camber angles and propulsion angles. When doing four-wheel alignment, the positioning angle of the rear wheels is more important. The belief that “four-wheel alignment is to adjust the toe of the front wheels” is one-sided or even wrong.

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Misunderstanding 2: Wherever the fee is low, do four-wheel alignment

Since the beginning of the new century, with the rapid increase in the number of domestic vehicles, many domestic and foreign four-wheel alignment manufacturers have competed to occupy the market. Various forms of production and different quality positioners have sprung up to the market. This is unprecedented. Competition in the market has greatly reduced the profit margins of manufacturers and distributors. Positioner manufacturers with no intellectual property rights and no technical content are competing against each other. The relative popularity of locators has intensified the competition among maintenance companies, and many maintenance companies offer users a lower price. The low fees are not because the productivity of maintenance companies has increased, but more because of the low technical content and measurement accuracy of the equipment. In order to survive, some maintenance companies can only lack two things in positioning, and the positioning of vehicles is problematic. Naturally, there is no fundamental solution.

Misunderstanding 3: Practitioners lack the necessary knowledge

The majority of employees in four-wheel alignment maintenance companies are rarely able to receive professional knowledge and skills training, and most of them stay in the state of self-learning while doing.

Misunderstanding 4: Maintenance personnel omit key operations

To deceive users Most users know very little about four-wheel alignment. It is difficult to question when positioning a car’s wheel, and it is even more difficult to give their own opinions. Some maintenance personnel avoid the key positioning operation steps in order to reduce the workload when doing four-wheel positioning, which makes the positioning detection result far from the actual situation. In addition, some maintenance personnel are not responsible, and do not perform pre-positioning inspections before positioning, and even the cracks of the half-axle rubber sleeve and the lower swing arm hinge joint rubber sleeve cannot be detected in time or the user is not notified, which will cause the user to be more serious in the future. Loss, repeated positioning and repeated charges.

Misunderstanding 5: I think it is the same with what kind of four-wheel alignment device

The qualification of the four-wheel alignment mainly depends on the skill of the maintenance personnel and the quality of the locator. Domestic four-wheel alignment devices can be described as complete categories, ranging from low-end 20,000 to 50,000 yuan, mid-end 50,000 to 100,000 yuan, to high-end 100,000 yuan. The price of low-end products is cheap, but users respond to more problems: low technical content, poor accuracy, and high failure rate. The market share of mid-range products is relatively large and can basically meet the needs of general users. High-end products are mostly imported products with high-tech, some are world-renowned brands, and the technology is excellent. Its positioning software and hardware are complete, more humane, and more efficient, and solve more problems for enterprises and users. , It can not only complete excellent wheel alignment work, but also help diagnose chassis faults. Have better economic and social benefits.

How to choose a four-wheel alignment instrument

In the domestic market, there are many brands and types of four-wheel positioning equipment. Due to its relatively high technical content, many users do not know much about its technical performance and measurement principles. Faced with the diverse and intricate product introductions of manufacturers, they are often at a loss when purchasing equipment. The following provides some reference suggestions on the main aspects:

How to make a price-performance ratio

The price difference of four wheel positioning of different brands is extremely different. Since the country has no corresponding regulations on the production of four-wheel positioning products, domestic products are mixed. For example, although some brand equipment is equipped with a computer, the computer is only used for the management of model data. The sensor is not connected to the computer, and the sensor data cannot be The computer showed that the user was cheated after purchasing.

Some equipment is used as an imported flag to deceive users, and some equipment cut corners; some manufacturers use imported low-end sensors for simple assembly, and their lack of sensor maintenance technology makes users’ equipment failures unable to be timely and effectively eliminated: popular positioning equipment * cheap You can buy more than 20,000 to 30,000 yuan, while expensive equipment (generally speaking, imported equipment) costs hundreds of thousands or even hundreds of thousands. Generally speaking, you get what you pay for. However, the price of imported equipment is relatively high due to factors such as tariffs and layered price increases by agents.

Different brands of equipment have different costs due to their advanced technology, production technology, configuration, etc., so the market sales prices are also different.

Technically, users can identify the technical performance of the equipment from the following aspects:

A, whether to use DSP technology

DSP or Digital Signal Processor (DigitalSignalProcessor) is a dedicated processor for high-speed real-time processing of digital signals, and its processing speed is 10-50 times faster than the fastest CPU. In the early days, DSP was mainly used in military products. Later, with the continuous development of large-scale integrated circuits and the continuous reduction of cost, it was gradually applied to civilian products. Because DSP has powerful computing power, the use of DSP in the sensor not only improves the data measurement speed and measurement accuracy, but also greatly improves the anti-interference ability of the measurement.

The four-wheel alignment products using DSP have the following characteristics:

Toe beam measurement has strong anti-light interference ability: In the four-wheel aligner that adopts light measurement, infrared or laser transceiver sensors are generally used to measure the toe beam data of the vehicle. Since sunlight or ordinary light sources have components with the same wavelength as the measured light, the data measured by light will be affected by this and deviate from the correct measurement result. For this reason, some positioning devices use filters to reduce the influence of external light, but they cannot completely eliminate the influence of external light. This is the reason why many four-wheel aligners need to draw the curtains when measuring under the sun. However, if you use curtains to block the outside light at night or in other weak light environments, it will be difficult to use curtains. If the DSP technology is used to modulate the measurement light line, the modulated infrared light has different characteristics from sunlight or other light sources, and the modulated measurement light is demodulated and filtered when receiving, so that it can be guaranteed The measurement result is not interfered by other light. The cost of DSP technology equipment for DSP is relatively high, and the price of advanced technology is relatively high.

B. Is the electronic level used?

In order to achieve the designed measurement accuracy, the popular four-wheel aligner must ensure that the four probes are always level at the same time during the measurement process. The non-level state of any probe may cause erroneous measurement results. For the four-wheel aligner that adopts the blister type indicator, the operator must pay careful attention to whether each probe is in a horizontal state, which not only distracts the operator’s energy, but also inevitably prevents mismeasurement. If an electronic level is installed on all four probes, the level status data of the sensor probes will be transmitted to the computer in time. The computer monitors the level data of each sensor probe and prompts the operator in time when a probe is not level. In this way, not only the work intensity of the operator is reduced, but also the mis-measurement operation is easily avoided. Among the imported equipment, the Hunter of the United States and Bossh of Germany have adopted electronic level in their positioning equipment, and their prices are also relatively expensive.

C. Is an electronic turntable used?

In the positioning parameters, the caster angle and the caster angle of the kingpin cannot be directly measured, and can only be measured indirectly based on the geometric relationship: turn the front wheel 20 degrees to the left and right, and measure the camber and caster angles respectively. Calculate the caster angle and the inclination angle of the kingpin according to a certain functional relationship. Therefore, the measurement of the caster angle and the inclination angle of the kingpin is closely related to the measurement of the steering angle. Steering angle When the steering angle is 20 degrees and 20.5 degrees, the relative error of the detected kingpin angle results is 2.39%, which far exceeds the requirements of the detection accuracy. It can be seen that the error of the turntable has a huge impact on the detection result. Therefore, the forthcoming national industry standard stipulates that in 2005, the four-wheel aligner must use an electronic corner plate. In addition, the use of the electronic corner plate greatly improves the automation of the measurement process and shortens the measurement time. All foreign high-end four-wheel aligners use electronic turntables.

D. Is the data communication method infrared or radio?

E. Transmission technology: The cost of radio communication equipment is higher than that of infrared transmission equipment; the 8-to-beam system is higher than the 6-to-beam measurement system, and the electronic level is higher than that of the water bubble type.

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F, measurement accuracy;

G, measurement repeatability;

H, measure the reaction speed.

In addition, equipment stability, repeatability, failure rate, maintenance price, etc. are also very important factors, but it is difficult to obtain this information from the manufacturer properly, correct and objective information, and users need to obtain it from the side.

After sales service

In the automotive inspection and maintenance products, the after-sales service of the four-wheel alignment device has a more important meaning, and the after-sales service content is more abundant and complex. Due to its relatively high price, timely maintenance services must be provided after the equipment fails. Due to its high technical content, only those manufacturers with technical development capabilities can provide the highest quality maintenance services. For manufacturers without technical capabilities, they often use the method of replacing large parts such as sensor probes and main control boards to repair customer equipment. Not only is the maintenance cost high, the user is unbearable, and the time is often not timely.

The operation of four-wheel positioning equipment is more complicated, and manufacturers are required to provide high-quality operation training services. For those users who are not very familiar with the car chassis, the manufacturer must also have the ability to locate the fault and adjust the car. In addition, due to the continuous emergence of new models, manufacturers are also required to update the vehicle positioning data in a timely manner.

In summary, users must carefully verify the manufacturer’s after-sales service capabilities in the above-mentioned aspects before purchasing four-wheel alignment equipment.

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