As the car moves, the suspension stiffness varies with load and road surface. The car requires lowering the height of the car on a good road and increasing the speed of the car; increasing the height of the car on the bad road and increasing the passing capacity, thus requiring the height of the car to be adjusted according to the requirements of use. Air spring type non-independent suspensions can meet such requirements.
It consists of a compressor, a gas cylinder, a height control valve, an air spring, a control rod, etc., in addition to a damper, a guide arm, a stabilizer bar, and the like. The air spring is fixed between the frame (body) and the axle, and the height control valve is fixed on the vehicle body, wherein the end of the piston rod is hinged with the cross arm of the control rod, and the other end of the cross arm is hinged with the control rod, and the cross arm is The middle part is supported on the upper part of the air spring, and the lower end of the control rod is fixed on the axle. The components that make up the air spring are connected together via a pipe. The high-pressure gas generated by the compressor enters the air reservoir through the oil-water separator and the pressure regulator, and then exits the gas-storage cylinder and then enters the height control valve through the air filter. The gas flowing out of the height control valve flows through the air filter. The gas storage tank is connected to the air springs on the respective wheels, so that the gas pressure in each air spring increases with the increase of the inflation amount, and the body is lifted up until the piston in the height control valve is directed to the gas storage tank The inflated inflation port is blocked. As an elastic element, the air spring can alleviate the impact load acting on the wheel from the road surface when it is transmitted to the vehicle body via the axle. In addition, the air suspension can also automatically adjust the height of the car body. The piston is located between the inflation port and the venting port in the height control valve, and the gas from the air reservoir inflates the air reservoir and the air spring, and raises the height of the vehicle body. When the piston is in the upper position of the inflation port in the height control valve, the gas in the air spring flows back to the air outlet through the inflation port, and the air pressure in the air spring drops, so that the height of the vehicle body also drops. The lever and the cross arm on it determine the position of the piston within the height control valve.
The air suspension has a series of advantages such as good smoothness of the car, uniaxial or multi-axis lifting when needed, and changing the height of the car body and small damage to the road surface, but also has a complicated structure and strict sealing requirements. And so on. It is used in commercial buses, trucks, trailers and some passenger cars.