AT455737 83040488 AT428960 AT302661 AT353758 Hydraulic High Pressure Variable Piston Oil Pump AT354782

I. Technical Parameters
Core performance parameters
– Pump type: Swash plate axial piston variable pump, constant power + constant pressure compound control, right-rotating steering, open circuit design, suitable for medium and high-pressure hydraulic systems, providing adjustable hydraulic source for small and medium-sized actuators.
– Displacement and pressure parameters: Rated displacement 50 mL/r, variable range 8%-100% stepless adjustment; Rated working pressure: 31.5 MPa, maximum allowable pressure: 35 MPa (short-term ≤10 seconds); The rated speed is 1800 r/min, the maximum speed is 2200 r/min (short-term ≤5 minutes), and the minimum stable speed is 180 r/min.
– Flow and efficiency parameters: Rated flow at rated speed is 90 L/min, and the flow response time is ≤50 ms. Volumetric efficiency ≥93%, total efficiency ≥87%; The imported vacuum degree is ≤0.03 MPa (at rated speed).
– Operating characteristics: Continuous operating oil temperature ≤85℃, rated working condition noise value ≤83 dB (measured at 1 meter); The fault-free operating life under rated conditions is ≥ 12,000 hours.
2. Structure and connection parameters
– Structural type: Swash plate axial piston structure, integrating alloy cast iron pump body, stainless steel piston pair, tin bronze cylinder body, roller bearing and composite control valve group; The axial clearance compensation device is adopted, resulting in low leakage under high pressure.
– Core material: The plunger is made of stainless steel (surface hardened, hardness HRC60-63); The cylinder body is made of tin bronze ZCuSn10Pb5 (hardness HB220-250). The swash plate is made of alloy steel with a ceramic coating (hardness above HV850). The sealing part is a high-pressure resistant fluororubber combination (temperature resistance ≤110℃).
– Connection specifications: The oil suction port (P) is of G1.25″ thread, and the oil return port (T) is of G1″ thread. The drive shaft is spline connected (specification: 20×45). Install flange bolts with a center distance of 160×120 mm. The weight of the pump body is approximately 55 kg, and its external dimensions (length × width × height) ≈520×380×300 mm.
3. Medium and Environmental requirements
– Medium requirements: L-HM 46 anti-wear hydraulic oil is suitable for normal temperature, and L-HM 32 is selected for low temperature (below -20℃). The allowable medium viscosity is 15-350 mm²/s, with a moisture content of no more than 0.02%. Solid particles (particle size > 5 μm) are strictly prohibited.
– Cleanliness standard: The oil cleanliness should reach ISO 4406 15/12 grade. A 5 μm fine filter should be placed in front of the oil suction port. The filter should be replaced when the pressure difference of the filter is greater than 0.12 MPa.
– Environmental parameters: Operating environment temperature -25℃ to 90℃, relative humidity ≤95%; With a protection grade of IP65, it is suitable for small and medium-sized construction machinery, industrial high-pressure equipment and other scenarios.Ii. Working Principle
This pump is a swashplate axial piston variable pump. Its core achieves high-pressure adjustable hydraulic energy output through the mechanism of “swashplate driving the piston to reciprocate – cylinder volume change – compound control flow regulation”. The specific process is as follows:
1. Core process of oil suction and discharge
The drive shaft rotates the cylinder block, and the plunger tightly adheres to the swash plate under the action of the return spring. When the plunger rotates to the lower side of the swash plate (the oil suction zone), the inclined plane pushes the plunger to extend outward, increasing the volume of the plunger cavity and creating a negative pressure. The hydraulic oil is then sucked in through the oil suction port and the filter. When rotating to the upper side of the swash plate (oil discharge area), the plunger is compressed and retracted inward, reducing the volume. High-pressure oil is discharged to the system through the oil discharge port, and the cylinder body continuously rotates to achieve continuous oil suction and discharge.
2. Compound variable regulation mechanism
Constant power + constant pressure compound control is adopted: when the system pressure is lower than 31.5 MPa, the constant power control takes effect, and the flow rate automatically decreases according to the rule of “pressure × flow rate = constant power” as the pressure increases. When the pressure reaches 31.5 MPa, the constant pressure valve drives the variable mechanism to reduce the inclination Angle of the swash plate, and the flow rate drops to 8% of the rated displacement, avoiding overpressure and achieving the self-adaptation of “high pressure with small flow rate and low pressure with large flow rate”.
3. Pressure stability guarantee
Built-in high-pressure relief valve (opening pressure 33 MPa) and oil replenishment valve: The relief valve is urgently unloaded when the compound control fails. The oil replenishment valve replenishes oil when the pressure in the oil suction area is too low to prevent cavitation, and at the same time replenishes the leaked oil in the circuit to maintain stable efficiency.

Iii. Product Features and Advantages
– Precise and efficient medium and high pressure variable: With a rated pressure of 31.5 MPa and a displacement of 50 mL/r, the rated flow rate is 90 L/min, and the flow regulation accuracy is ≤2%. Compound control saves more than 28% energy compared to quantitative pumps and is suitable for variable load scenarios (such as the main circuit of excavators).
– Long wear resistance and service life: The design of hardened plunger and ceramic coating on the swash plate improves the wear resistance by 60% compared with ordinary plunger pumps. The axial clearance compensation device keeps the volumetric efficiency stable at over 93% for a long time, with a rated service life of ≥ 12,000 hours and low operation and maintenance costs.
– Strong load adaptability: The compound control can achieve dynamic balance of flow and pressure without external components. The torque fluctuation is ≤3% at the minimum stable speed of 180 r/min, making it suitable for precision high-pressure operations (such as hydraulic forming).
– Good installation compatibility: Standardized flange and spline connection, which can directly replace old pumps of the same specification; With an IP65 protection rating, it can resist dust and water splashing, making it suitable for complex outdoor and workshop environments. The installation and commissioning efficiency is increased by 40%.

Iv. Usage Functions and Purposes
1. Core usage functions
– Medium and high-pressure variable oil supply: It provides 31.5MPa adjustable oil source for small and medium-sized actuators (high-pressure hydraulic cylinders, high-torque motors), with flow rate adjustable from 8% to 100% in a stepless manner, replacing the “fixed displacement pump + relief valve” combination and reducing energy consumption.
– Intelligent load adaptation: It responds in real time to changes in load pressure and automatically adjusts the flow rate, such as switching the loader from “lifting heavy load (31.5 MPa, 15 L/min) to traveling light load (20 MPa, 90 L/min)” without manual intervention.
– Multi-actuator collaborative drive: Through the valve group, oil can be supplied to 2-3 actuators simultaneously. The flow rate is distributed as needed, and the pressure fluctuation is ≤ 0.6MPa, which is suitable for the multi-action scenarios of “mixing + unloading” of concrete mixer trucks.
2. Main application fields
In the field of small and medium-sized construction machinery: 20-30 ton excavator main pumps, 15-25 ton loader lifting circuits, 10-15 ton roller vibration drives, suitable for infrastructure and light-load operations in mines.
In the field of industrial high-pressure equipment: 800-1200 ton hydraulic forming machines, injection circuits for medium-sized die-casting machines, and power sources for high-pressure test benches, suitable for precision manufacturing scenarios.
– Special fields: Luffing circuits for small cranes in ports, drives for small roadheaders in mines, power sources for high-pressure cleaning equipment, suitable for intermittent high-pressure operations.

V. Applicable Machines and Scenarios
1. Adapt to the core machine
– Small and medium-sized construction machinery: 20-30 ton excavators, 15-25 ton loaders, 10-15 ton rollers.
– Industrial equipment: 800-1200 ton hydraulic forming machines, medium-sized die-casting machines, high-pressure hydraulic test benches.
– Special equipment: Small port cranes, small mine roadheaders, high-pressure water jet cleaning machines.
2. Typical application scenarios
– Excavator main pump scenario: As the main pump of a 25-ton excavator, the compound control enables the switching between “excavation heavy load (31.5 MPa, 18 L/min) – rotation light load (22 MPa, 90 L/min)”, completing 45 excavation cycles per hour. With IP65 protection, it is suitable for the dusty environment of mines.
– Hydraulic forming machine scenario: It is equipped with a 1000-ton forming machine. The constant pressure is controlled at 31.5 MPa for 8 minutes (the flow rate is reduced to 5 L/min), ensuring the forming accuracy of metal parts. The volumetric efficiency is ≥93%, which is 30% more energy-efficient than the fixed displacement pump.
– Loader lifting scenario: Drive the lifting cylinder of a 20-ton loader, output a pressure of 30 MPa and a flow rate of 85 L/min, and drive the bucket to complete the “lifting – unloading” cycle, with 35 operations per hour, suitable for earthwork transportation on construction sites.

Six. Similar models
1. Alternative models of the same series
-AT455735: A small-displacement model of the same structure, with a rated displacement of 40 mL/r and a rated flow rate of 72 L/min. The pressure parameters are consistent, suitable for 15-20 ton equipment (such as 20-ton loaders), and the cost is 20% lower.
-AT455739: A large-displacement model of the same series, with a rated displacement of 63 mL/r and a rated flow rate of 113.4 L/min, and the same pressure. It is suitable for equipment ranging from 30 to 35 tons (such as 30-ton excavators), but the cost is 30% higher.
2. Cross-series alternative models
-AT455737-D: Constant voltage single control model, with constant power function removed, suitable for constant load (such as high-voltage holding system), consistent parameters, and 15% lower cost.
-AT455737-M: Medium-pressure model, rated pressure 25 MPa, consistent displacement and flow rate, suitable for medium-pressure systems (such as 600-ton molding machines), with a 25% lower cost.
-AT455737-L: Left-hand rotating model, with the same structural performance, compatible with left-hand power sources, and the cost is the same.

Vii. Precautions for Use
1. Medium management
– Select L-HM 32/46 anti-wear hydraulic oil. Mixing is strictly prohibited. Before using the new pump, flush the pipeline with clean oil for more than 60 minutes to ensure that the cleanliness meets ISO 4406 15/12 grade.
– Check the filter pressure difference weekly (replace the filter element when it exceeds 0.12 MPa), measure the oil moisture content monthly (≤0.02%), and measure the cleanliness every two months. When the oil emulsifies or contains grinding debris, stop the machine immediately, change the oil and clean it.
2. Installation and commissioning
– Confirm that the drive shaft is rotated to the right. Reverse rotation is strictly prohibited. The coaxiality error between the drive shaft and the motor should be no more than 0.05mm to avoid uneven load wear.
Before debugging, manually turn the wheel 2-3 times to ensure no jamming. The first start-up involves replenishing oil at 5 MPa and running it no-load at 500 r/min for 25 minutes. Gradually increase the rated parameters. A flow error of ≤2% is considered normal.
Outdoor installation with a protective cover ensures IP65 protection; The pump body is horizontally fixed, with a heat dissipation space of ≥ 150mm reserved. A cooler is added when the oil temperature exceeds 85℃.
3. Operation and Maintenance
Monitor the pump body temperature (normal ≤80℃, maximum ≤90℃), pressure and variable response; When the temperature rises sharply above 18℃ or the pressure fluctuates by more than 1 MPa, the machine should be shut down to check the cleanliness of the oil or the wear of components.
– Maintenance every 6,000 hours: Clean the pump body and check the plunger cylinder clearance (replace if > 0.015mm). Replace the sealing parts and bearings, and test the pressure and flow rate to meet the standards before use.
It is strictly prohibited to run the machine without oil (> 3 seconds for sintering), under long-term overpressure (> 35 MPa), or at excessive speed (> 2200 r/min). Before shutting down, run at low speed without load for 8 minutes. Only when the oil temperature is ≤60℃ should the power be cut off.
4. Storage protection
For long-term storage, seal the oil port, add anti-rust oil and apply grease to the shaft. Store in a dry warehouse with a temperature range of 0-45℃ and a humidity of no more than 60%. Rotate the vehicle once a month.
Before being put into use after being idle for more than 18 months, clean the inner cavity and replace the sealing parts. After low-pressure flushing, conduct a 20-minute trial run. Only when it meets the standards can it be connected to the system.