A4VTG090 A4VTG071 Rexroth Axial Piston Pump 400 bar

Product Overview

The A4VTG090HW100/33MRNC4C92F0000AS-Y and A4VTG071HW100/33MRNC4C82F0000AS-0 are the 90 cc-class and 71 cc-class core models within the Bosch Rexroth A4VTG series 33 axial piston variable pumps with swashplate design. The A4VTG series is specifically engineered as a high-pressure pump for the drum drive in mobile concrete mixers, operating as a closed-circuit pump with a nominal pressure of 400 bar and maximum pressure of 450 bar.

Model Code Breakdown (for procurement and engineering reference):

• A4VTG: Rexroth swashplate axial piston variable pump, closed circuit, for concrete mixer drum drive

• 090 / 071: Nominal size (NG), geometric displacements of 90 cm³/rev and 71 cm³/rev respectively

• HW100: HW = proportional control hydraulic, mechanical servo, hexagon shaft with lever at rear; 100 = control variant code

• /33: Series 33

• MRNC4: M = mounting flange code; R = clockwise rotation (viewed from shaft end); N = NBR seals; C4 = port and filtration configuration code

• C92 / C82: Control module variant codes

• F0000AS: Additional configuration code

• -Y / -0: Factory calibration and version identifier

Drop-in Replacement Advantage: Manufactured to exact Rexroth OEM specifications, these pumps are dimensionally matched for SAE J744 4-hole mounting flange, shaft dimensions, port layout, and HW control module interface, achieving complete drop-in interchangeability with the original A4VTG series 33. Every pump undergoes 100% simulated load testing prior to shipment, validating 400 bar pressure loading, HW control response, and volumetric efficiency under conditions replicating real-world duty cycles.

Technical Specifications 

Model A4VTG090HW100/33MRNC4C92F0000AS-Y:

• Model Code: A4VTG090HW100/33MRNC4C92F0000AS-Y

• Series: Rexroth A4VTG Series 33 (Closed Circuit, Swashplate Design)

• Nominal Size: NG 90

• Geometric Displacement (Variable Pump): 90 cm³/rev

• Auxiliary Pump Displacement: Approx. 25.7 cm³/rev (at p = 20 bar)

• Nominal Pressure: 400 bar (continuous)

• Peak Pressure: 450 bar (intermittent)

• Maximum Speed (at Vg max): 3050 rpm

• Maximum Flow (at Vg max and n nom): 275 L/min

• Maximum Power (at Δp nom): 183 kW

• Maximum Torque (at Vg max and Δp nom): 573 N·m

• Control Type: HW — Proportional control hydraulic, mechanical servo, hexagon shaft with lever at rear

• Control Angle Range: 0° to ±29° (stepless 0–100%)

• Rotation: Clockwise (R code, viewed from shaft end)

• Mounting Flange: SAE J744 4-hole flange (D code)

• Seal Material: NBR (nitrile rubber)

• Housing Material: High-strength cast iron

• Weight: Approx. 53 kg

• Operating Temperature: 30–90°C

• Fluid Cleanliness: ISO 4406 18/15/12 or better

Model A4VTG071HW100/33MRNC4C82F0000AS-0:

• Model Code: A4VTG071HW100/33MRNC4C82F0000AS-0

• Series: Rexroth A4VTG Series 33 (Closed Circuit, Swashplate Design)

• Nominal Size: NG 71

• Geometric Displacement (Variable Pump): 71 cm³/rev

• Auxiliary Pump Displacement: Approx. 18.7–19.6 cm³/rev (at p = 20 bar)

• Nominal Pressure: 400 bar (continuous)

• Peak Pressure: 450 bar (intermittent)

• Maximum Speed (at Vg max): 3300 rpm

• Maximum Flow (at Vg max and n nom): 234 L/min

• Maximum Power (at Δp nom): 156 kW

• Maximum Torque (at Vg max and Δp nom): 452 N·m

• Control Type: HW — Proportional control hydraulic, mechanical servo, hexagon shaft with lever at rear

• Control Angle Range: 0° to ±29° (stepless 0–100%)

• Rotation: Clockwise (R code, viewed from shaft end)

• Mounting Flange: SAE J744 4-hole flange (D code)

• Seal Material: NBR (nitrile rubber)

• Housing Material: High-strength cast iron

• Weight: Approx. 51 kg

• Operating Temperature: 30–90°C

• Fluid Cleanliness: ISO 4406 18/15/12 or better

Key Technical Advantages

1. Closed-Circuit Design Optimized for Concrete Mixer Drum Drive
The A4VTG series is specifically engineered for the drum drive in mobile concrete mixers as a closed-circuit high-pressure pump. Compared to open-circuit systems, closed-circuit designs offer compact structure, higher efficiency, and smaller reservoir volume — ideal for space-constrained mobile equipment like concrete mixers. Pump flow is proportional to drive speed and displacement, with flow increasing smoothly as the swashplate angle adjusts from zero to maximum. Flow direction changes smoothly when the swashplate is moved through the neutral position.

2. HW Hydraulic Proportional Control with Stepless Displacement Adjustment
The HW100 control is a proportional control hydraulic, mechanical servo with a hexagon shaft and lever at the rear. Pump output flow can be steplessly varied from 0 to 100%, proportional to the rotation of the control lever between 0° and ±29°. The control unit supplies control pressure to the pump’s stroke cylinder via pilot pressure, driving the swashplate to change its inclination angle for precise displacement adjustment. A feedback lever connected to the stroke piston maintains pump flow for any given current within the control range. This control method offers intuitive operation and rapid response, particularly suitable for concrete mixer operators controlling drum speed directly from the cab.

3. Integrated Auxiliary Pump and Closed-Circuit Charge System
The A4VTG pump incorporates an integrated auxiliary pump (boost pump) that serves as both feed pump and control pressure supply. Auxiliary pump displacement: approximately 25.7 cm³/rev for size 90 and 18.7–19.6 cm³/rev for size 71 (at p = 20 bar). The auxiliary pump provides cooling and leakage compensation flow for the closed circuit while supplying control oil pressure to the HW control module. Maximum boost pressure is limited by a built-in boost pressure-relief valve. The high-pressure relief valves also function as boost valves, protecting the hydrostatic transmission from overload.

4. Swashplate Design with High Power Density
The A4VTG employs a swashplate axial piston variable pump design where piston stroke is determined by swashplate inclination angle. The size 90 achieves maximum power of 183 kW and maximum torque of 573 N·m at 400 bar nominal pressure; the size 71 achieves 156 kW and 452 N·m respectively. The high power density delivers large displacement output in a compact envelope, satisfying the mixer drum drive power requirements under fully loaded conditions.

5. Drop-in Interchangeability with High-Strength Cast-Iron Housing
The A4VTG090HW100/33MRNC4C92F0000AS-Y and A4VTG071HW100/33MRNC4C82F0000AS-0 are dimensionally matched to the original Rexroth A4VTG series 33 specification for SAE J744 4-hole mounting flange, shaft dimensions, port layout, and HW control module interface, achieving complete drop-in interchangeability. The high-strength cast-iron housing provides superior structural damping, effectively suppressing structural vibration and fluid-borne noise.

Application Areas

• Concrete Mixer Trucks: Drum drive in mobile concrete mixers (the core application of the A4VTG series)

• Concrete Transport Equipment: Batching plant mixer hydraulic drives, concrete pump truck auxiliary hydraulic systems

• Construction Equipment: Other mobile equipment requiring closed-circuit high-pressure hydraulic drives

• Energy-Saving & Environmental Equipment: Closed-circuit hydrostatic drive systems for energy-efficient construction equipment

Expert Maintenance Tips

1. Hydraulic Fluid Cleanliness
The A4VTG series HW control unit spool operates with extremely tight clearances and is highly sensitive to particulate contamination. The control unit slide valve can be blocked in an undefined position by internal contamination (impure hydraulic fluid, foreign matter). System fluid cleanliness must meet ISO 4406 18/15/12 or better. Install a filter in the boost pump suction line (F code designation). Replace filter elements at 500 hours after first commissioning, then every 1,000 operating hours or 6 months, whichever comes first.

2. HW Control Lever Operating Procedure
HW control adjusts displacement via the rear hexagon shaft and control lever, with a lever rotation range of 0° to ±29°. Operate the lever smoothly, avoiding rapid large-angle movements that cause system pressure spikes. With the lever at neutral (0°), pump displacement is zero and the pump delivers only leakage compensation flow. After extended shutdown, position the lever at neutral before restarting, allow the system to build boost pressure, then slowly adjust to the working position.

3. Closed-Circuit Charge Pressure Monitoring
The A4VTG pump’s integrated auxiliary pump provides charge pressure for the closed circuit, with maximum boost pressure limited by a built-in boost pressure-relief valve. Regularly check that charge pressure is normal (typically 15–20 bar). Insufficient charge pressure causes piston slippers to lose contact with the valve plate, resulting in dry wear. Excessive charge pressure increases system heat generation. Inspect the boost pressure-relief valve setting and sealing condition every 2,000 operating hours.

4. High-Pressure Relief Valve Inspection and Maintenance
The pump’s built-in high-pressure relief valves (pilot-operated, fixed setting, with bypass) protect the hydrostatic transmission from overload and also function as boost valves. Inspect the relief valve setting pressure every 2,000 operating hours to confirm it remains below the 450 bar peak pressure and that the bypass function operates correctly. Replace relief valve components if frequent opening or setting drift is observed.

5. Pre-Start Priming and Air Bleeding
Before first start, fill the pump housing with clean hydraulic fluid through the case drain port. After installation, turn the drive shaft by hand several revolutions to confirm free rotation without binding. Position the HW control lever at neutral (zero displacement) and run at low speed for 5–10 minutes. Verify continuous bubble-free flow from the case drain. Only after confirming adequate lubrication and charge pressure should the pump be loaded.