What is four-wheel alignment? Please talk about the principle of four-wheel positioning and dynamic balance.

The so-called four-wheel alignment means that the set positions of four tires deviate from a certain angle in the vertical and horizontal directions according to the design idea of the vehicle. Maybe you will ask, isn't the tire perpendicular to the ground? Actually, it's not. Go to the front of the car, squat down and observe the left and right front wheels carefully. Especially after lifting the vehicle, you will find that the two front wheels seem a little splayed, and the lower edges of the wheels are folded inward. This is camber. If you look further, you will find that the front wheels are not balanced, but the leading edge is slightly inward. This is called "toe-in".

Why is this happening? This is because when the vehicle is empty and loaded, the angle of the tire will change under the action of force, so the design deviation is certain, which can ensure that the tread can completely contact the ground when the vehicle is really loaded, and achieve the best grip and uniform wear. Due to the existence of camber and the soft rubber on the tread edge, the front tire always tends to spread outward and run off, so the toe-in should be designed to prevent the tire from running off. Both the front and rear wheels of the wheel have such angle setting problems, but the front wheel is responsible for steering function, so it is more important. Similarly, due to the mechanical complexity of the front wheel, the damage probability is much higher than that of the rear wheel, so the four-wheel positioning is mainly to locate the front wheel. On the hub edge of automobile wheels, some have one or more small lead blocks with different sizes. Compared with all kinds of beautiful wheels, these small lead blocks seem a little out of harmony. But it is these small lead blocks that play a very important role in the stability of high-speed driving.

The wheel of a car is a whole composed of tires and wheels. However, due to manufacturing reasons, the mass distribution of all parts of the whole can not be very uniform. When the automobile wheels rotate at high speed, it will form a dynamic imbalance state, which will cause wheel jitter and steering wheel vibration when the vehicle is running. In order to avoid or eliminate this phenomenon, it is necessary to correct the balance of each edge part of the wheel by adding counterweight under dynamic conditions. This correction process is usually called dynamic balance.

Tires should be regularly checked for dynamic balance and checked with a dynamic balance tester. Wheel balance can be divided into dynamic balance and static balance. Dynamic imbalance will make the wheels shake and make the tires wear in waves; Static imbalance can cause bumps and jumps, which often leads to flat spots on tires. Therefore, checking the balance regularly can not only prolong the service life of tires, but also improve the stability of cars when driving, and avoid traffic accidents caused by the tire swinging, jumping and out of control when driving at high speed.

According to the principle of mechanical movement, the owner turns the wheel on the shaft with the computer, and then embeds the wire in a certain part. For the wheel with high speed, the main inertia axis passing through the center of gravity of the wheel does not coincide with the rotation axis due to the inhomogeneity of the material structure, the size error of the part shape, the assembly size error and the structural shape error, so that the wheel will produce unbalanced centrifugal force when rotating, especially for the automobile wheel running at high speed. Rotating for more than ten times per second, even if there is a small eccentric torque, will cause great unbalanced force, which will lead to the continuous vibration of the wheel, especially the vibration of the steering wheel, which will lead to the shaking of the steering wheel, accelerate the wear of suspension and steering system components, and accelerate the wear of bearings in the wheel. It is also difficult to drive a car with strong vibration, and it is not safe to drive. So the wheel balance is a very important job for modern cars. Before leaving the factory or after running for a period of time, the wheels should be balanced and debugged, and the unbalance inside and outside the rim should be measured, and the balance weight should be embedded in the appropriate position on the rim to achieve the balance accuracy of the wheels.

The balance weight is made of lead alloy and weighs in grams, including 5g,10g,15g and up to15g and 6 specifications. There is a steel hook on the counterweight, which can be embedded in the rim edge and is very firm. Then the tire should be repaired and replaced with new tires for dynamic balance.