The three stage hydraulic gear pump, with its efficient, durable and easy-to-maintain features, has become a reliable power core for high pressure hydraulic systems. It is commonly used in construction machinery, metallurgical equipment, mining machinery, and other fields. This page will introduce the working principle of the three stage hydraulic gear pump, helping you quickly understand and make a choice.
Core Components and Functions
Pump Housing and End Covers
The gear pump housing contains three independent and connected gear chambers, each accommodating a set of gears. The end cover is installed on both sides of the pump body to seal the gear chambers, prevent oil leakage, and provide installation support for the bearings. At the same time, on the end cover, an inlet port and an outlet port will be reserved to ensure that the oil flows in the path of “first stage → second stage → third stage”.
Three Stage Gear Sets—Core Working Component
Each gear set consists of 1 driving gear and 1 driven gear. You can see three gear sets are driven by the same driving shaft or achieve synchronous operation through gear transmission. The outlet of the previous gear set is directly connected to the inlet of the next gear set. The meshing clearance of the gear set needs to be strictly controlled. It is necessary to ensure that the hydraulic oil can pass through the clearance for lubrication, and also to avoid pressure loss and flow leakage due to excessive clearance.
Bearings and Sealing Components
Bearings support the high speed rotation of the gear shaft. They can reduce friction and wear between the shaft and end cover, ensuring stable meshing of the gear pair. The sealing assembly includes shaft end seals and static seals between the pump body and end cover. Shaft end seals prevent fluid leakage from the drive shaft extension end, while static seals block fluid pathways between the gear chamber and the external environment. They also isolate dust and contaminants from entering the pump body, protecting the gear pair from contamination.
How does a Three Stage Gear Pump Work?
Step 1: Oil Suction and Initial Boost
When the motor drives the rotating shaft, the driving gear of the first gear set drives the driven gear to rotate in the opposite direction. In the suction chamber of the gear set, the volume between the teeth increases as the gears separate, creating a local vacuum. Under the action of atmospheric pressure, the hydraulic oil in the oil tank is drawn into the suction chamber through the inlet.
Then, the sucked oil is carried into the pressure chamber along with the rotation of the gears. As the volume between the teeth decreases with the meshing of the gears, the oil is compressed and enters the suction chamber of the second gear set. At this point, the output pressure P1 of the first stage is obtained.
Step 2: Secondary Boosting
The oil entering the second-stage oil intake chamber undergoes the same “volume change” process as in the first stage under the meshing operation of the second-stage gear set. The oil pressure rises again, and then it is pushed into the oil intake chamber of the third-stage gear set to complete the “secondary boosting”. At this point, the output pressure P2 of the second stage is obtained.
Step 3: Final Boost and Output
The medium-pressure oil output from the second stage enters the third-stage oil suction chamber. Under the compression effect of the third-stage gear set, the pressure undergoes a third superposition, ultimately reaching the rated high pressure P3 of the pump.
At this point, the high-pressure oil in the third-stage oil pressure chamber is transported through the pump body outlet to the hydraulic system, such as high pressure hydraulic cylinders and hydraulic motors. It provides power to the actuating elements to meet the high-load requirements. After the system actuating elements complete their actions, the oil flows through the return pipeline back to the oil tank, waiting for the next cycle.
The Ideal and Actual Pressure
Ideal pressure: If your parameters of the three-stage pump cores are exactly the same and there is no leakage, the theoretical output pressure ≈ P1 + P2+ P3.
Actual pressure: The latter two pump cores are in a high pressure environment, especially the third stage. You will find that the leakage of the oil through the gap will be greater. Therefore, the actual output pressure is slightly lower than the ideal pressure.
Conclusion
The three stage gear pump is an important mechanical component in the hydraulic system. We are here to explain the structure and work principle, hope you can choose the gear pump which is suitable for you. If you need to purchase a three stage hydraulic pump, please feel free to contact Target. From model selection consultation to after sales support, we will provide you with an appropriate solution throughout the process.
