AP2D28 Hydraulic Pump Used For DX55/60
1. Product Overview
AP2D28 is a swashplate type variable displacement tandem axial piston pump. It acts as the main hydraulic power source for Doosan DX55 and DX60 mini crawler excavators.
This pump adopts dual-pump integrated structure, generally integrated with built-in pilot gear pump. It supplies pressurized hydraulic oil to control boom, arm, bucket, slewing and traveling movements. High-quality interchange aftermarket pump can directly replace the original pump for machine maintenance and overhaul.
Model Definition
- AP2D: Series code of variable axial piston pump
- 28: Single pump theoretical displacement: 28 cc/rev
- Suitable Equipment: Doosan DX55, DX60 Mini Excavator
2. Main Technical Parameters
Item Specification
Pump Type Tandem Variable Displacement Axial Piston Pump
Single Pump Displacement 28 cc/rev
Control Mode Negative flow control
Rated Working Pressure 25.5 MPa
Maximum Peak Pressure 30 MPa
Rated Rotating Speed 2100 rpm
Max Self-priming Speed 2600 rpm
Rotation Direction Clockwise
Built-in Component Integral pilot pump
Applicable Hydraulic Oil ISO VG46 anti-wear hydraulic oil
Operating Temperature -20℃ ~ +85℃
Seal Material NBR; FKM sealing kit optional
Approximate Weight 35 kg
3. Working Principle
Driven by the engine, the main shaft and cylinder block rotate synchronously. The reciprocating movement of pistons realizes oil suction and high-pressure oil discharge.
The built-in servo piston adjusts the tilt angle of swashplate automatically according to system load signals, changes pump displacement and regulates output flow.
The integrated pilot pump provides stable pilot pressure for pilot control circuit, driving pilot joysticks and foot valves to realize all operation actions of excavator.
4. Core Advantages
1. Compact integrated structure with main pump and pilot pump together, saving installation space for 5–6 ton mini excavators.
2. Precisely machined internal friction pairs, low internal leakage, high volumetric efficiency during continuous operation.
3. Stable negative flow control, good power matching with engine, effectively reducing fuel consumption.
4. Cast high-strength pump housing, shock-resistant and anti-vibration, adaptable to various construction conditions.
5. Mounting flange, spline shaft, oil port layout fully consistent with OEM pump, plug-and-play direct replacement.
6. Cost-effective aftermarket replacement solution with short delivery cycle.
5. Application Range
Main hydraulic pump for Doosan mini excavators:
Doosan DX55, Doosan DX60
Widely used in urban construction, landscaping, pipeline engineering and small earthwork projects.
6. Common Faults & Replacement Suggestion
Typical failures: Weak digging force, slow working actions, high oil temperature, abnormal knocking noise, shaft seal oil leakage.
Completely flush hydraulic pipelines and replace all hydraulic filter elements before installation. Keep hydraulic oil clean to prevent impurities from scratching piston and valve plate. Replace whole pump assembly if internal components suffer severe wear.
