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 demanding on oil cleanliness, cheaper in price; however, the pump shaft is subject to unbalanced forces, severe wear and tear, and large 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: has high volumetric efficiency, small leakage, can work under high pressure, and is mostly used in high-power hydraulic systems; but it has a complex structure, high requirements for materials and processing accuracy, is expensive, and requires high oil cleanliness.
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.
