The working principle and structure of the hydraulic system are commonly used connectors. The hydraulic power transmission part of the rubber tube is a high-pressure rubber tube assembly, some of which are represented by a circuit diagram to show the relationship between different functional elements. 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 working oil; the executive part contains hydraulic cylinder or hydraulic motor, which can be selected according to the actual requirements.

In the analysis and design of practical tasks, the block diagram is generally used to display the actual operation status of the equipment.

White arrows represent signal flow, while black arrows represent energy flow.

Action sequence in basic hydraulic circuit - reversing and spring return of control element (two position four-way reversing valve), extension and retraction of executive element (double acting hydraulic cylinder) and opening and closing of overflow valve.

For the executive and control components, the presentation is based on the corresponding circuit diagram symbols, which also prepares for the introduction of circuit diagram symbols.

Depending on how the system works, you can number all circuits in turn. If an actuator number is 0, the control element identifier associated with it is 1. If the component identifier corresponding to the actuator extension is even, the component identifier corresponding to the actuator retraction is odd.

Not only the hydraulic circuit should be numbered, but also the actual equipment should be numbered in order to find the system fault.

DINISO 1219-2 standard defines the number composition of components, which includes the following four parts: equipment number, circuit number, component identifier and component number. If there is only one device in the whole system, the device number can be omitted.

In practice, another numbering method is to continuously number all components in the hydraulic system. At this time, the component number should be consistent with the number in the component list. This method is especially suitable for complex hydraulic control systems. Each control loop corresponds to its system number.