Product Overview
The A4VG140EP4D1/32R-NAF02F021DP is a Bosch Rexroth A4VG Series swashplate-type axial piston variable displacement pump with a displacement of 140 cm³, belonging to the Series 32 closed-circuit high-pressure pump family. Featuring EP (electric proportional) control, it operates at a nominal pressure of 400 bar and can withstand peak pressures up to 450 bar, purpose-built for hydrostatic transmission systems in construction machinery, mining equipment, and heavy vehicles.
Manufactured to original Bosch Rexroth specifications with guaranteed drop-in interchangeability, this pump directly replaces the OEM A4VG140 series pump without modification to mounting interfaces or hydraulic plumbing. Critical rotating components — including the cylinder block, pistons, valve plate, and drive shaft — are precision-machined to OEM tolerances. The mounting flange, spline configuration, and port locations are identical to the original. Every unit undergoes 100% simulated working-condition dyno testing prior to shipment, including rated pressure cycling, EP control response verification, and leakage inspection, ensuring volumetric efficiency, pressure stability, and dynamic response meet OEM-equivalent standards.
Technical Specifications
Model: A4VG140EP4D1/32R-NAF02F021DP
Series: Rexroth A4VG Series 32
Type: Swashplate axial piston variable displacement pump (closed circuit)
Displacement: 140 cm³/rev
Nominal Pressure: 400 bar
Maximum Pressure: 450 bar
Maximum Speed: 2,500 rpm
Maximum Flow (at nmax): 350 L/min
Maximum Torque (Δp=400 bar): Approx. 890 N·m
Control Type: EP electric proportional control (with pressure control)
Rotation: Clockwise (R = right-hand, viewed from shaft end)
Mounting Flange: SAE standard flange
Shaft: ISO standard splined shaft
Weight: Approx. 106 kg (standard configuration)
Charge Pump: Integrated
Pressure Cut-off: Standard integrated
Case Drain Port: Standard
Hydraulic Fluid: Mineral-based hydraulic oil (ISO VG 32–68)
Filtration: ISO 4406 cleanliness level 20/18/15 or better
Key Technical Advantages
1. Swashplate Design for Efficient Closed-Circuit Transmission
The A4VG140 utilizes a swashplate-type axial piston variable pump design, optimized for closed-circuit hydrostatic transmission. The swashplate angle varies steplessly from the zero position in both directions, with flow increasing linearly with swashplate angle. Zero flow output is achieved at the neutral position. When the swashplate crosses the zero position, flow direction changes smoothly without the need for directional valves, making it ideal for bidirectional speed control in propel drive systems.
2. EP Electric Proportional Control — Precise Remote Control
EP control receives electrical signals through proportional solenoids (solenoids a and b), combined with a pressure control valve for precise displacement regulation. The control method supports remote electronic operation and seamlessly integrates with machine electronic control systems (such as propel controllers), enabling fine control, closed-loop speed control, and engine-pump power matching. The standard integrated pressure cut-off automatically reduces pump displacement to zero when system pressure reaches the set value, effectively protecting hydraulic components from overpressure damage.
3. Integrated Charge Pump and High-Pressure Relief Valves
An integrated charge pump maintains positive pressure in the closed circuit, preventing cavitation and compensating for system leakage. The charge pump shares the drive shaft with the main pump, requiring no additional mounting space or drive interface. Two high-pressure relief valves protect the high and low pressure sides respectively, and also function as feed valves — automatically supplying charge oil when circuit pressure drops below charge pressure. Charge pressure is limited by the built-in charge pressure relief valve for safe system operation.
4. Through Drive and Modular Auxiliary Mounting
The pump features a through drive, allowing a second auxiliary pump (such as an equal-size A4VG pump or gear pump) to be mounted directly on the rear of the pump, forming a compact tandem assembly without separate support brackets or additional drive interfaces. This modular design significantly reduces axial installation length, reducing system complexity and installation costs.
5. High-Strength Cast Iron Housing and Long-Life Bearing System
The pump housing is cast from high-strength iron with wall thickness distribution optimized through finite element analysis, balancing 400 bar pressure capability with compact construction. The drive shaft is supported by large-diameter bearings capable of withstanding both the axial forces from swashplate displacement and radial loads from the drive end. Bearing preload is precisely calculated to maintain stable running clearance across the full speed range, extending service life.
Application Areas
The A4VG140EP4D1/32R-NAF02F021DP is widely used in the following equipment:
Vibratory roller propel drive systems
Motor grader propel hydraulic circuits
Wheel loader hydrostatic transmissions
Concrete pump truck hydraulic drives
Mining LHD propel circuits
Agricultural machinery (tractor hydraulic drive systems)
Heavy forklifts and material handling equipment
Municipal specialty vehicle hydraulic transmissions
Expert Maintenance Tips
Pre-Installation Checks: Verify that the pump shaft spline matches the drive end configuration before installation. Apply a light coating of grease to the spline surface. Ensure full contact between the mounting flange and the mounting pad. Never force the pump into position by tightening the fixing bolts, as this may cause abnormal bearing preload or housing deformation. Confirm that the rotation direction (R = right-hand, viewed from shaft end) matches the drive end.
Oil Cleanliness Control: A4VG series pumps are sensitive to fluid contamination. System oil cleanliness should be maintained at ISO 4406 level 20/18/15 or better. Under high-pressure operating conditions (400 bar), a cleanliness level of 19/17/14 is recommended. Suction filters should be rated at 10 μm or finer; charge pressure filters at 10 μm or finer are recommended. Check suction line sealing before first start-up to prevent air ingress.
EP Control Module Maintenance: Periodically inspect the electric proportional control module wiring and connectors for tightness. Control signal lines should be routed away from high-voltage ignition lines and other electromagnetic interference sources. If sluggish displacement response or system oscillation is observed, first inspect the control module electrical connections, proportional solenoid operation, and pressure control valve settings.
Case Drain Management: The case drain line must remain unrestricted; case pressure must not exceed the rated value. Route the drain line directly to the reservoir below the oil level to avoid backpressure affecting pump displacement control. Periodically inspect the drain line for loosening or wear caused by vibration.
Start-Up and Break-In: During initial start-up, operate at low speed and low pressure for 10–15 minutes to purge air from the system and check all connections for leakage. Fill the pump case with clean hydraulic oil through the case drain port before starting to prevent dry-start damage to the rotary group. Ensure the suction line is filled with hydraulic fluid before charge pump start-up.
