9J5764-WS25KAA-251111 Hydraulic Gear Pump 231-6587 10R-7978 Excavator 9J5764

I. Technical Parameters
This gear pump belongs to the high-pressure quantitative gear pump specially designed for excavators and is a core power component of the hydraulic system in construction machinery. Its nominal displacement is 25ml/r, which is suitable for the flow requirements of the pilot system of excavators and medium and small load working circuits. The rated working pressure can reach up to 25MPa, and the short-term peak pressure can reach 35MPa, which can cope with the load impact during excavation operations. The rated speed is 2200r/min, and the maximum speed does not exceed 2500r/min. Within this speed range, the flow rate can be stably output.
The volumetric efficiency is no less than 92% under rated working conditions, and the total efficiency is no less than 82%. It can reduce energy loss and slow down the rate of oil temperature rise during operation. The pump body is made of high-strength gray cast iron, and the key sealing parts inside adopt secondary sealing technology. The viscosity range of the compatible hydraulic oil is 20-500mm ²/s. It is recommended to use 46# or 68# anti-wear hydraulic oil. The working temperature adaptation range is -20 ℃ to 80℃, which can adapt to most outdoor working environments. The installation method adopts flange connection, and the connection dimensions comply with SAE standards. The weight is approximately 15kg, which is convenient for integration with the hydraulic system of the excavator. In the model, 9J5764 is the series and basic model code, WS25 represents the compatible specification with a displacement of 25ml/r, KAA is the code for sealing and structural configuration, and 251111 is the exclusive code for the production batch and compatible model.Ii. Working Principle
This gear pump follows the core working principle of positive displacement pumps and relies on the rotation of a pair of intermeshing driving gears and driven gears within the pump body to complete the oil suction and pressure processes. Its internal structure includes key components such as the pump body, front and rear end covers, gear shafts, bearings and sealing devices. The driving gear is connected to the power output shaft of the excavator.
After startup, the driving gear drives the driven gear to rotate synchronously in the opposite direction. At this time, on one side of the oil suction chamber, the gears gradually disengage from the meshing state, and the volume of the closed space formed between the teeth continuously increases, thereby generating a local vacuum. The hydraulic oil in the oil tank is sucked in through the suction port under the action of atmospheric pressure and fills the gaps between the teeth. As the gears continue to rotate, the space between the teeth carrying the oil moves to the side of the oil pressure chamber, and the gears start to mesh. The volume between the teeth is gradually compressed, and the oil pressure rises after being squeezed. Eventually, it is conveyed to the hydraulic actuator system of the excavator through the oil pressure port. When the gears keep rotating, a continuous and stable supply of hydraulic oil is formed, providing power support for various movements of the excavator.

Iii. Product Features and Advantages
Strong pressure resistance and impact resistance: The side plate structure with special surface treatment, combined with high-strength pump body material, can effectively withstand the frequent load fluctuations and pressure impacts during excavator operation. Even under peak pressure conditions, it is less likely to cause shell deformation or internal component damage. The application of secondary sealing technology has further enhanced the sealing performance under high-pressure conditions and reduced the risk of oil leakage.
Outstanding anti-pollution and durability: The internal gears and bearings have undergone special wear-resistant treatment, which has a high tolerance for slight impurities in the hydraulic oil. It can adapt to the outdoor dusty and complex working environment of excavators and reduce the probability of failure caused by oil contamination. At the same time, special pressure-controlled rolling bearings are adopted. Compared with ordinary bearings, the service life can be significantly extended and the number of equipment shutdowns for maintenance can be reduced.
Stable operation and low noise: The optimized gear tooth profile design reduces mechanical shock during meshing. The operating noise at the rated speed does not exceed 66dB, which can improve the operating environment for excavator drivers. Moreover, the flow output pulsation is small, which can make the boom, bucket arm and other actuating components of the excavator move smoothly, avoiding the occurrence of jamming or shaking during operation.
Compact structure and easy adaptation: The overall structure is simple, with strong universality of components, and the installation dimensions comply with general standards. This not only facilitates installation and layout within the limited space of the excavator but also makes the disassembly and replacement of components relatively easy during subsequent maintenance, reducing the difficulty and time cost of maintenance.

Iv. Usage Functions and Purposes
Its core function is to provide a stable high-pressure oil source for the hydraulic system of the excavator. As a power core component, it controls the output and delivery of hydraulic oil, thereby driving the excavator’s boom lifting and lowering, boom extension and retraction, bucket digging, and rotation of the rotary platform, etc. At the same time, it can be coordinated with the control valve group in the excavator’s hydraulic system to achieve the action switching and collaborative work of different actuating elements, such as the linkage action between the bucket and the boom during excavation operations.
In addition, this gear pump can also serve as an auxiliary power source, providing low-pressure control oil for the pilot control circuit of the excavator to ensure the precise transmission of operation instructions. In some modification scenarios, it can also be used to drive the additional devices of the excavator, such as the high-frequency impact action of the breaker, which is a key power component to ensure that the excavator can complete various earthwork and crushing operations.

V. Applicable Machines and Scenarios
Core compatible machines: Mainly compatible with medium and small-sized excavators, covering general-purpose excavators of 10-20 tons. It can also be compatible with multi-functional construction machinery of the same tonnage such as excavators and loaders, and is compatible with the main working circuit or pilot control circuit of such equipment.
Outdoor excavation scenarios: In foundation pit excavation and foundation leveling operations during construction, it can stably provide power for excavation actions. In the pipeline laying and road repair operations of municipal engineering, it can meet the operation requirements of precise speed control and ensure smooth movements. In light stripping operations in mines or quarries, its impact resistance and anti-pollution properties can cope with harsh working conditions with a lot of dust and high loads.
Other extended scenarios: Besides excavators, it can also be adapted to the hydraulic systems of small loaders, crawler cranes and other construction machinery, and is used to drive the working devices of such equipment. It can also be applied to the hydraulic circuits of auxiliary equipment in mines, providing power support for the opening, closing and action execution of the equipment.

Six. Similar models
Model of the same series but different displacement: 9J5764-WS33KAA-251112. The displacement of this model has been increased to 33ml/r, with a larger rated flow rate, making it suitable for the main working circuit of large excavators. 9J5764-WS18KAA-251110, with a displacement of 18ml/r, is more suitable for the pilot control circuit of excavators or the power supply of small operation devices.
Model of the same specification but different configurations: 9J5764-WS25KAB-251111, equipped with FKM seals resistant to high and low temperatures, suitable for operation in high-altitude or extremely cold regions. 9J5764-WS25KAC-251111, featuring an axial clearance floating compensation structure, offers higher volumetric efficiency and is suitable for long-term continuous operation conditions.
Cross-series compatible models: For instance, the CBZ2-25WS gear pump suitable for loaders, with displacement and pressure parameters similar to this pump but slightly different structures, can be used for auxiliary circuit modification in excavators. There is also a gear pump with a displacement of 25ml/r in the P7600 series, which features high pressure and can be used as an alternative to this pump in the hydraulic systems of similar construction machinery.

Vii. Precautions for Use
Installation specification: During installation, it is necessary to ensure that the coaxiality error between the pump shaft and the power output shaft does not exceed 0.05mm to avoid bearing wear and abnormal gear meshing caused by eccentricity. The flange connection bolts should be evenly tightened to prevent oil leakage due to poor adhesion of the installation surface. The diameter of the oil suction pipe must not be less than the inlet diameter of the pump, and the length of the oil suction pipeline should be shortened as much as possible to reduce the oil suction resistance and prevent cavitation.
Oil control: Before the first installation and use, the hydraulic oil tank and pipelines of the excavator must be thoroughly cleaned to prevent welding slag, iron filings and other impurities remaining during the installation process from entering the pump body and scratching the gears and seals. The cleanliness of the hydraulic oil should comply with the 20/18/15 grade as stipulated in ISO 4406. The oil condition should be checked regularly on a daily basis. If emulsification, deterioration or excessive impurities occur, it should be replaced immediately. At the same time, keep the oil temperature within the appropriate range to prevent the oil temperature from being too high to accelerate the aging of the sealing parts, and too low to affect the flexibility of the valve core’s operation.
Operation: When starting the excavator, it is necessary to idle to preheat the hydraulic system, and gradually increase the system pressure to avoid damaging the internal structure of the pump body due to sudden high-pressure impact. During operation, avoid keeping the pump in peak pressure condition for a long time to reduce overload operation time. If abnormal heating of the pump body, increased noise or oil leakage is detected, the machine must be stopped immediately for inspection. Do not force operation.
Maintenance and care: Regularly clean the surface of the pump body on a daily basis to prevent the accumulation of dust and oil stains that may affect heat dissipation. Every 2000 hours of operation, check the gear meshing clearance and the wear of the bearings. If the clearance exceeds the standard or the bearings make abnormal noises, the components should be replaced in time. A comprehensive disassembly and maintenance should be carried out every 5,000 hours. Replace the seals and worn vulnerable parts. When reassembling, apply an appropriate amount of hydraulic oil to lubricate the moving parts to ensure smooth operation after assembly.