420 421 ADU62 421AK 420AK Series 421AK01229B Hydraulic High Pressure Piston Pump ADU049R32AB10AA4321000002AD000CD00A

I. Technical Parameters
Core performance parameters
– Pump type: Swash plate axial piston variable oil pump, with pressure compensation variable function, suitable for power supply in medium and high pressure and small and medium flow hydraulic systems.
– Pressure rating: Rated working pressure 31.5 MPa, continuous operating pressure ≤31.5 MPa; The instantaneous peak pressure is 35 MPa (lasting no more than 5 seconds). The variable pressure adjustment range is 10-31.5 MPa.
– Flow parameter: Rated displacement 49 mL/r (corresponding to model “049” marking); When the rated speed is 1500 r/min, the rated flow rate is approximately 73.5 L/min. The speed adaptation range is 800-2000 r/min, and the flow rate is linearly matched with the speed (approximately 39.2 L/min at 800 r/min and approximately 98 L/min at 2000 r/min).
– Efficiency and power: Under rated working conditions, the volumetric efficiency is ≥93%, and the total efficiency is ≥88%. At 1500 r/min, the input shaft power should be ≤40 kW, and the power of the matching motor is recommended to be 37-45 kW.
2. Structure and connection parameters
– Structural type: Horizontal installation swash plate structure, integrated pressure compensation variable mechanism; The cylinder block is splined to the input shaft. The six plungers are evenly distributed around the circumference, and the maximum inclination Angle of the swash plate is 15°.
– Core material: The plunger is made of alloy structural steel (20CrNiMoA, nitrided, surface hardness HV850-950); The swash plate is made of bearing steel (GCr15, quenched hardness HRC58-62). The pump body is made of cast steel (ZG35CrMo, quenched and tempered).
– Connection specifications: The diameter of the oil suction port (S port) is Φ 25mm, and the diameter of the oil pressure port (P port) is Φ 20mm. The thread specifications are all M30×2. The flange installation complies with the ISO 7005-2 standard, and the input shaft is connected by a flat key (keyway specification 10×8).
3. Medium and Environmental requirements
– Medium requirements: L-HM 46 anti-wear hydraulic oil is recommended. L-HV 46 is selected for low temperatures (below -20℃). The kinematic viscosity of the oil is 30-100 mm²/s, and the moisture content is ≤0.1%.
– Cleanliness standard: The oil cleanliness should reach ISO 4406 16/13 grade. An 80 μm coarse filter should be installed at the suction port, and a 10 μm fine filter (β10≥100) should be installed at the pressure port.
– Environmental parameters: Operating temperature -20℃ to 80℃, relative humidity ≤95%; The protection grade is IP54, suitable for working conditions with vibration acceleration ≤10 m/s².Ii. Working Principle
This pump is a swash plate type axial piston variable oil pump. It realizes the conversion of hydraulic energy and mechanical energy through “swash plate driving the piston to reciprocate – periodic change of sealed volume for oil suction and discharge – pressure feedback regulating flow”. The specific process is as follows:
1. Basic processes of oil absorption and oil pressure
The motor drives the input shaft to rotate the cylinder at high speed. Under the combined action of centrifugal force and the return spring, the six plungers are always in close contact with the end face of the swash plate. When the plunger rotates with the cylinder to the lower side of the swash plate (the oil suction area), the inclined surface of the swash plate pushes the plunger to extend outward. The sealed volume formed by the plunger and the cylinder gradually expands, generating a vacuum suction force. The hydraulic oil is sucked into the sealed cavity through the oil suction window of the distribution plate. When the plunger rotates to the upper side of the swash plate (the oil pressure area), the swash plate compresses the plunger to retract into the cylinder, rapidly reducing the sealed volume. The oil is pressurized by the compression and then output to the hydraulic system through the oil pressure window of the distribution plate. Each time the cylinder block rotates once, each plunger completes one oil suction and pressure action, achieving continuous and stable oil supply.
2. Pressure compensation variable regulation mechanism
– Low-load high-flow mode: When the system load is low and the pressure is less than the set value, the thrust of the pressure oil on the variable piston is less than the spring preload force. The variable mechanism remains stationary, the swash plate maintains the maximum inclination Angle, and the pump outputs the maximum displacement (49 mL/r), which is suitable for the rapid action requirements of the equipment (such as the rapid advance of the hydraulic cylinder).
– High-pressure low-flow mode: When the system pressure rises to the set value, the thrust of the pressure oil is greater than the spring force, which drives the variable mechanism to reduce the inclination Angle of the swash plate, shorten the plunger stroke, and the pump displacement decreases accordingly. The flow rate decreases linearly with the increase in pressure, achieving “high-pressure flow limiting” and reducing energy loss.
– Overpressure protection mechanism: When the system pressure reaches a peak of 35 MPa, the swash plate inclination Angle suddenly drops to nearly 0°, and the displacement drops to a level that can only compensate for leakage, achieving automatic unloading and preventing damage to the pump body and system components due to overpressure.

Iii. Product Features and Advantages
– Medium and high pressure compatibility, precise power matching: With a rated pressure of 31.5MPa and a rated flow rate of 73.5L /min, it is suitable for medium and small-sized heavy-duty equipment. Compared with gear pumps of the same flow rate, the pressure is more than doubled, and it can directly drive medium and high pressure actuators (such as small hydraulic presses) without the need for a pressure increase device.
– Variable energy saving and low operating cost: Flow regulation range 12%-100%, pressure fluctuation ≤±0.3 MPa; When the equipment operates under pressure or at a low speed, the flow rate automatically drops to the minimum, saving 25% to 35% energy compared to a fixed displacement pump. Long-term operation can significantly reduce electricity expenses.
– Compact structure and high reliability: The symmetrical distribution design of the 6 plungers ensures even force distribution on the cylinder body and low operating vibration. The plunger nitriding and swash plate quenching treatment enhance the wear resistance. Under rated working conditions, the trouble-free operation life reaches 10,000 hours, which is 30% longer than that of ordinary plunger pumps.
– Wide working condition compatibility and flexible installation: A wide speed range of 800-2000 r/min can be matched with standard three-phase asynchronous motors; The horizontal installation structure is compact in size (approximately 300×200×180 mm in length × width × height) and weighs no more than 50 kg, making it suitable for scenarios with limited installation space.
– Easy maintenance and universal wear parts: The modular pump core design allows for the replacement of wear parts such as the plunger and seals by removing the front cover. The vulnerable parts are compatible with those of the same series of small-displacement pumps, with low procurement costs and a replacement time of no more than 1.5 hours.

Iv. Usage Functions and Purposes
1. Core usage functions
– Variable flow regulation: Automatically ADAPTS to compound working conditions such as “fast advance – working advance – pressure holding – fast retreat”, with a flow range of 8.8-73.5 L/min. No additional flow control valve is required, simplifying the system pipeline design.
– Medium and high-pressure power supply: It provides a stable oil source of 31.5MPa for small and medium-sized hydraulic cylinders and hydraulic motors, driving heavy-duty actions (such as workpiece pressing and material grasping), with a pressure control accuracy of ± 0.5MPa.
– Overpressure automatic protection: Automatic unloading at a peak pressure of 35 MPa, replacing an external relief valve and reducing system integration costs; The variable pressure can be set steplessly by adjusting the screw to adapt to different load requirements.
– Load adaptive operation: When there is a sudden load change (such as when an excavator is digging hard soil), the flow rate is quickly adjusted within 0.3 seconds to avoid pipeline vibration or component damage caused by pressure shock, thereby enhancing operational stability.
2. Main application fields
– Construction machinery: Main working system of 5-10 ton small excavators, lifting mechanism of 3-5 ton loaders, vibration drive system of small rollers, steering assistance system of forklifts.
– Light industry manufacturing equipment: 100-300 ton small CNC hydraulic press, 100-200 ton injection molding machine clamping system, precision bending machine hydraulic system, fully automatic tablet press power source.
– Agricultural and forestry machinery: Large tractor suspension and lifting systems, combine harvester header drive mechanisms, forestry logging machine grasping devices.
– Specialized equipment: small and medium-sized hydraulic test benches, power pumps for high-pressure cleaners, hydraulic systems for ship deck machinery (small cranes).

V. Applicable Machines and Scenarios
1. Adapt to the core machine
– Construction machinery: 5-10 ton crawler excavators, 3-5 ton wheel loaders, small vibratory rollers, 3-5 ton internal combustion forklifts.
– Industrial equipment: 100-300 ton hydraulic presses, 100-200 ton injection molding machines, small CNC bending machines, fully automatic tablet presses.
– Agricultural and forestry equipment: Tractors with over 120 horsepower, self-propelled combine harvesters, and small and medium-sized forestry harvesters.
– Specialized equipment: Small and medium-sized hydraulic test benches, high-pressure cleaning equipment, small deck cranes for ships.
2. Typical application scenarios
– Small excavator operation: During the combined action of the 8-ton excavator boom and bucket, the variable pressure is set at 28 MPa, and the output flow rate is 73.5 L/min when fast-advancing without load (boom lifting speed 0.8 m/s). When the pressure of hard soil excavation rises to 31.5 MPa, the flow rate should be reduced to 15-20 L/min to maintain a stable excavation force and prevent engine overload.
– Small hydraulic press pressing: When a 200-ton hydraulic press presses metal workpieces, it outputs a flow rate of 73.5 L/min at a speed of 1500 r/min to achieve rapid downward flow (speed 1.2 m/s). During the pressing stage, the pressure is raised to 31.5 MPa, and the flow rate is reduced to 8-12 L/min, ensuring that the forming accuracy of the workpiece is ≤±0.05 mm. The energy consumption in the holding pressure stage is reduced by 80%.
– Tractor suspension operation: When a 150-horsepower tractor is suspended with a plough for farming, the pump output pressure is 25-30 MPa, and the flow rate is adjusted according to the lifting speed of the suspension (10-50 L/min), which can meet the requirements of different farming depths. It can operate continuously in the field for 10 hours without failure.

Six. Similar models
1. Alternative models of the same series
-ADU035R32XXXX: A small-displacement model of the same structure, with a rated displacement of 35 mL/r (1500 r/min flow rate approximately 52.5 L/min), a rated pressure of 31.5 MPa, and installation dimensions fully compatible with the original model. It is suitable for light-load scenarios (such as small bending machines), and the cost is 15% lower.
-ADU063R32XXXX: A large-displacement model of the same series, with a rated displacement of 63 mL/r (1500 r/min flow rate approximately 94.5 L/min), a rated pressure of 31.5 MPa, and the same structural materials. It is suitable for medium and large-sized scenarios (such as 10-ton excavators), but the cost is 20% higher.
2. Cross-series alternative models
-ADU049R32-H: A high-pressure upgraded model, with a rated pressure of 35 MPa and a displacement of 49 mL/r. The materials of the plunger and pump body have been upgraded (the surface of the plunger is coated with ceramic), suitable for high-pressure precision scenarios (such as hydraulic test benches), and the cost is 30% higher.
-ADU049R32-P: Constant power variable model, with a total efficiency of ≥89%, suitable for scenarios with large fluctuations in load power (such as the luffing mechanism of small cranes). Its energy-saving effect is 5% to 8% higher than that of pressure compensation type, but the cost is 25% higher.
-ADU050R30XXXX: A similar displacement alternative model, with a rated displacement of 50 mL/r, a rated pressure of 31.5 MPa, compatible installation dimensions, a flow deviation of ≤2%, can be used as an emergency alternative model, and the cost is similar.

Vii. Precautions for Use
1. Oil management
It is mandatory to use L-HM 46 anti-wear hydraulic oil. In low-temperature environments (below -20℃), it should be replaced with L-HV 46 hydraulic oil. Different grades and types of oil must not be mixed. The oil of the new pump must be replaced after the first 500 hours of operation. Subsequently, it should be replaced every 1500 hours. Before changing the oil, the oil tank and pipelines should be flushed with new oil. After flushing, the cleanliness of the oil should reach ISO 4406 17/14 grade.
When the pressure difference of the oil suction filter exceeds 0.2 MPa and that of the oil pressure filter exceeds 0.5 MPa, the filter element should be replaced immediately. The moisture content (≤0.1%) and acid value (≤ 0.15mgKOH /g) of the oil should be tested monthly. When they exceed the standards, dehydration or replacement with new oil should be carried out in a timely manner. It is strictly prohibited to use emulsified, deteriorated or oil containing metal impurities to prevent abnormal wear of the plunger and swash plate.
2. Installation and commissioning
When installing, the coaxiality error between the pump shaft and the motor shaft should be no more than 0.1mm (for rigid connection) or no more than 0.3mm (for elastic connection), the flatness of the installation flange surface should be no more than 0.05mm /m, and the bolts should be evenly tightened with a torque of 150 N·m to ensure good sealing and no leakage. The height from the oil suction port to the oil surface of the oil tank shall be no more than 0.6m, and the diameter of the oil suction pipeline shall be no less than Φ 25mm to reduce the oil suction resistance and prevent cavitation.
Before the first start-up, the pump body should be filled with hydraulic oil (added through the oil filling port), and the pump body should be manually turned 3 to 5 times to ensure that the plunger moves flexibly without jamming. When starting, it should run no-load for 10 minutes (at a speed of 1000 r/min). Wait until the oil temperature rises above 30℃ before gradually loading. The pressure increase rate should be no more than 1 MPa/ minute to avoid damage to the plunger and distribution plate caused by high-pressure impact.
Variable pressure adjustment should be carried out through a dedicated adjusting screw. Turning the screw clockwise increases the set pressure, while turning it counterclockwise decreases the pressure. When adjusting, a pressure gauge should be used for real-time monitoring. After adjusting 1/4 turn, it should be stabilized for 1 minute. It is recommended that the set pressure does not exceed 90% of the rated pressure (i.e., ≤28.35 MPa). After adjustment, it should be fixed with a lock nut to prevent loosening.
3. Operation monitoring and maintenance
During operation, real-time monitoring of the pump body temperature (normal ≤75℃, maximum ≤85℃), inlet and outlet pressures (P port ≤ 31.5MPa, suction port vacuum degree ≤ 0.03MPa), and operating noise (≤ 82dB) is conducted. If a sudden temperature rise of ≥10℃, abnormal pressure fluctuations, or “unusual sounds” are detected, the machine should be immediately shut down for inspection. The key points to check are the cleanliness of the oil, the wear of the plunger or the jamming of the variable mechanism.
Regular maintenance should be carried out every 2,000 hours: replace seals, return springs and filter elements. Check the wear on the surface of the plunger (replace if it exceeds 0.02mm) and the flatness of the working surface of the swash plate (grind and repair if the error is greater than 0.005mm). Disassemble and inspect the wear of the cylinder block holes every 4,000 hours (if the roundness error is greater than 0.01mm, the cylinder block needs to be replaced).
Maintenance should be carried out in an environment with a cleanliness level of ≥1000. Before assembling parts, they should be cleaned with aviation kerosene and evenly coated with hydraulic oil. When assembling the plunger, handle it gently to avoid colliding with the working surface of the swash plate. After the variable mechanism is debugged, no-load and load tests should be conducted to ensure that the linearity error of flow regulation is ≤3%.
4. Storage and Idle protection
When stored for a long time, use a special metal plug to seal the oil suction port and the oil pressure port. Inject L-TSA 46 anti-rust oil into the pump body (the oil injection volume is 90% of the pump body volume). Place it in a dry and well-ventilated area (ambient temperature 5-35℃, relative humidity ≤60%). Manually turn the pump by hand twice a month to prevent the plunger from adhering to the cylinder body and the metal parts from rusting.
Before putting the pump into use after being idle for more than 6 months, drain the anti-rust oil from the pump body, flush the pump body twice with L-HM 46 hydraulic oil, and after each flush, introduce 2-3 MPa low-pressure oil to test the flexibility of the plunger. After installation, gradually load to 50%, 75%, and 100% of the rated pressure. Run each stage for 15 minutes. After confirming that the flow rate and pressure are stable and there is no leakage, put it into formal use.