One end of the valve spring is supported on the cylinder head or cylinder block, while the other end is pressed against the spring seat at the end of the valve rod, and the spring seat is fixed at the end of the valve rod with a locking piece. In order to prevent the spring from resonating, a cylindrical spring with variable pitch (such as the valve spring of the 8V100 engine of the Hongqi sedan) can be used. Most high-speed engines have a valve with two inner and outer valve springs installed concentrically. In this way, the reliability of the valve spring can be improved, that is, not only can resonance be prevented, but also when one spring is broken, the other can maintain operation. In addition, the height of the valve springs can be reduced. When two valve springs are installed, the helical directions of the spring coils should be opposite. This prevents a broken coil from getting caught in another coil. The 680Q engine, 492Q engine and CA6102 engine all use dual valve springs.Decentralized systems have become the preferred structure when designing production plants. These systems are in contrast to older centralized systems where all machines and equipment were connected to one control panel and one room. Decentralized systems are much more efficient by allowing decisions to be made at the application site (or edge). By placing controls close to the application, various parts of the system can operate independently. This is very important when flexibility is required.