First, hydraulic knowledge 1) Basic knowledge of hydraulic transmission and control. There are three main problems here. First, a large part of the books you can see now are relatively classic and old, and most of the new developments have not been reflected. This requires readers to find some targeted information to supplement. For example, many books still use the controlled sequence valve for balance valves used in engineering machinery. Who dares to use it now? And the new balance valve can only be found in samples and papers. Secondly, people generally have a good understanding of hydraulic transmission, but many people don’t know much about electro-hydraulic control technology. Today’s hydraulic system not only has the content of hydraulic transmission, but also the content of hydraulic control, such as proportional valves, servo valves, high-speed switch valves, servo cylinders, amplifiers, etc. People who only master general hydraulic transmission need to supplement in this regard. Thirdly, general textbooks introduce more industrial hydraulic devices and systems, and less introduction to walking machinery (engineering machinery, etc.). There are a number of books on engineering machinery hydraulic technology on the market, but most of the content comes from samples and host operating instructions, lacking unnecessary analysis. Another point is that the terminology that is different from general hydraulic technology is often used, which is quite a headache. For example, single-way steady flow valve, priority valve, distribution valve, etc., are actually fixed flow valve, fixed differential relief valve, proportional directional valve. To understand the original system diagram, you must also overcome this obstacle.
Second, I don’t need to say more about the importance of practical experience in understanding the system schematic diagram. It is difficult to really understand it based on book knowledge alone.
Third, graphic symbols. There are many types of hydraulic technology components and a wide range of applications. In addition, the technology is constantly developing. Although there are relevant international and national standards for graphic symbols, one is that the standards always cannot keep up with the development, and the other is that some manufacturers are just unconventional. Therefore, on the current hydraulic system oil circuit diagram, some seemingly inexplicable symbols often appear, which even hydraulic veterans sometimes feel troubled and headache. There are two solutions. One is to analyze its function from the overall perspective, and the other is to find out the rules of unconventionality from the sample. For example, the cartridge valve sample of oil control has many tricks, and you can understand it after careful analysis. For example, the symbol of the overflow valve always has to lead a line back from the outlet like the pressure reducing valve, which actually indicates the influence of back pressure, and there is nothing new. Fourth, the host requirements must be made clear, so that the analysis can have the right direction and not be blindly guessed. Fifth, if the system is relatively complex, it is recommended:
1) Divide the oil circuit diagram into three major parts: actuator, oil source, and control. First, according to the host requirements, clarify the actions and requirements of the actuator.
2) Clarify the oil source: single pump, multiple pumps; quantitative, variable; single supply, confluence.
3) Starting from the actuator, find the oil source pump in reverse and sort out the corresponding relationship;
4) Then analyze the control part of each pump and actuator chain.
5) If necessary, copy the oil circuit diagram of each basic action level (process) (mark the part of the oil circuit used in the process with color).
