708-2L-31114 7082L31114 excavator PC128-8UU hydraulic main pump

Commonly used types of hydraulic pumps:
1. According to whether the flow rate can be adjusted, it can be divided into: variable pump and fixed pump. The output flow can be adjusted according to needs is called a variable pump, and the flow cannot be adjusted is called a fixed pump.
2. According to the commonly used pump structures in hydraulic systems, they are divided into three types: gear pump, vane pump and plunger pump.
Gear pump: smaller in size, simpler in structure, less demanding on oil cleanliness, and cheaper in price; however, the pump shaft is subject to unbalanced forces, severe wear, and large leakage.
Vane pump: divided into double-acting vane pump and single-acting vane pump. This kind of pump has uniform flow, smooth operation, low noise, higher operating pressure and volumetric efficiency than the gear pump, and the structure is more complex than the gear pump.
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, a plunger pump is used when the gear pump and vane pump cannot meet the requirements. There are some other forms of hydraulic pumps, such as screw pumps, etc., but their appliTQions are not as common as the above three.