Hydraulic system working principle and structure commonly used connectors, rubber hose hydraulic power transmission parts for high pressure rubber hose assembly, part of the circuit diagram, to show the relationship between different functional components. The hydraulic source includes hydraulic pump, motor and hydraulic auxiliary components; The hydraulic control part contains various control valves, which are used to control the flow, pressure and direction of the working oil; The actuator contains hydraulic cylinder or hydraulic motor, which can be selected according to actual requirements. When analyzing and designing practical tasks, block diagrams are generally used to show the actual running status of equipment. Hollow arrows represent signal flow, while solid arrows represent energy flow.

The sequence of action in the basic hydraulic circuit - reversing and spring return of the control element (two-position four-way reversing valve), extending and retracting of the actuator element (double-acting hydraulic cylinder) and opening and closing of the relief valve. The presentation is based on the corresponding circuit diagram notation for both the actuator and the control element, which also prepares for the introduction of circuit diagram notation.

According to the working principle of the system, you can number all loops in turn. If each actuator is numbered 0, its associated control element identifier is 1. If the element identifiers corresponding to actuator extension are even, the element identifiers corresponding to actuator retraction are odd. Not only hydraulic circuits should be numbered, but also the actual equipment should be numbered to detect system failures.