Hydraulic shock absorber
The best solution is variable suspension characteristics, which use shock absorbers with variable damping force, such as hydraulic shock absorbers.
At the beginning of the XNUMXth century, more and more manufacturers are trying to offer customers more and more advanced cars. Now, safety and driving comfort are a priority, and these two factors are not easy to combine.
It is not possible to find the optimal characteristics of suspension damping elements (for example, shock absorbers and springs) for all road conditions. When the suspension is too soft 
Ride comfort is adequate, but when cornering, the vehicle body may lean and the road wheels may lose contact with the road surface. Then the safety factor of the car is at stake. To counteract this, the shock absorbers can be replaced with stiffer ones, but the car's occupants can get driving comfort comparable to that provided by a ladder car. The best solution is variable suspension characteristics depending on the type of road, speed and direction of travel. The suspension is then called active. It is quite simple and effective to use shock absorbers with variable damping force.
These shock absorbers use an additional valve to close or open additional oil flow. In this way, the performance characteristics of the shock absorber can be changed.
The opening or closing of the valve is controlled by a microprocessor, which receives signals from numerous sensors, such as steering wheel angle, vehicle speed or engine torque. In extensive systems, such as the new Porsche 911, the damping force can be adjusted individually for each of the four dampers on each wheel. In the Porsche 911, you can also change the damping force using a button located on the dashboard. There are two operating modes: normal and sports. When driving a Porsche in sport mode, the German highway becomes as uneven as the Polish roads, and the car becomes as stiff as if it had lost its suspension. But this is, of course, an extreme case.
So far, active suspension is used in expensive cars, but it will definitely gain popularity.
The variable damping hydraulic damper has a valve to close or open additional oil flow. The opening and closing of the valve is electronically controlled depending on the current road conditions and speed.
