A hydraulic component that provides pressurized fluid for hydraulic transmission and is a type of pump. Its function is to convert the mechanical energy of the power machine (such as electric motor and internal combustion engine, etc.) into the pressure energy of the liquid. There are many factors that affect the service life of hydraulic pumps. In addition to the design and manufacturing factors of the pump itself, it is also related to the selection of some components related to the use of the pump (such as couplings, oil filters, etc.), and the operation during the test run.

The working principle of a hydraulic pump is that movement brings about a change in the volume of the pump chamber, thereby compressing the fluid so that the fluid has pressure energy.

The necessary condition is that the pump chamber has a sealed volume change.

Types of commonly used hydraulic pumps:

1. According to whether the flow can be adjusted, it can be divided into: variable pump and quantitative pump. The output flow can be adjusted according to the needs is called the variable pump, the flow can not be adjusted called the quantitative pump.

2. According to the pump structure commonly used in the hydraulic system, it is divided into three types: gear pump, vane pump and plunger pump.

Gear pump: Smaller in size, simpler in structure, less strict on oil cleanliness, and cheaper in price; but the pump shaft is subjected to unbalanced forces, causing serious wear and leakage.

Vane pump: divided into double-acting vane pump and single-acting vane pump. This kind of pump has uniform flow, stable operation, low noise, higher operating pressure and volumetric efficiency than gear pumps, and more complex structure than gear pumps.

Piston pump: high volumetric efficiency, small leakage, can work under high pressure, and is mostly used in high-power hydraulic systems; but the structure is complex, the requirements for materials and processing precision are high, the price is expensive, and the cleanliness of the oil is high.

Generally, the plunger pump is used when the gear pump and the vane pump cannot meet the requirements. There are also some other forms of hydraulic pumps, such as screw pumps, etc., but their applications are not as common as the above three.