A4VG90 EP4DM2/32L Rexroth Closed Circuit Piston Pump 90cc 400bar

Product Overview

The A4VG40 / A4VG45 / A4VG56 / A4VG71 / A4VG90 series (example: A4VG90 EP4DM2/32L-NSF02F00-1FP) is a Bosch Rexroth axial piston variable pump of swashplate design for hydrostatic drives in closed circuits. Flow is proportional to drive speed and displacement and is infinitely variable; swivelling the swashplate through neutral smoothly reverses flow direction. The unit offers 100% drop-in interchangeability with genuine Rexroth pumps—no piping or mounting modifications required. Every unit undergoes full simulated operating-condition testing to guarantee high volumetric efficiency and reliability under high pressure and speed.

Technical Specifications 

• Model: A4VG40 / A4VG45 / A4VG56 / A4VG71 / A4VG90 (example: A4VG90 EP4DM2/32L-NSF02F00-1FP, Series 32)
• Geometric displacement (Vg max): 40 / 45 / 56 / 71 / 90 cm³/rev
• Nominal pressure: 400 bar (Series 32)
• Maximum pressure: 450 bar (single operating period max. 10 s)
• Maximum continuous speed at Vg max: A4VG40 ≈ 4000 rpm; A4VG56 ≈ 3600 rpm; A4VG71 ≈ 3300 rpm; A4VG90 ≈ 3050 rpm
• Minimum speed: 500 rpm
• Control: Electric proportional EP4 (24 V proportional solenoid, current-controlled displacement); other options include HD, HW, DA, DG, EZ
• Boost pump (typical, at p = 20 bar): approx. 8.6–19.6 cm³/rev (size-dependent)
• Weight (approx., without through-drive): A4VG40 ≈ 31 kg; A4VG56 ≈ 38 kg; A4VG71 ≈ 50 kg; A4VG90 ≈ 60 kg
• Design features: Closed circuit, swashplate design, integrated high-pressure relief valves with boost function, standard pressure cut-off, optional through-drive

Key Technical Advantages

1. Precision-machined swashplate and valve plate ensure flow strictly proportional to speed and displacement; smooth flow reversal through neutral minimises shock and noise.
2. High volumetric and overall efficiency is maintained in the high-pressure range; integrated boost pump and high-pressure relief valves protect the system and reduce external piping complexity.
3. Electric proportional EP control (EP4 = 24 V) provides precise linear current-to-displacement response with fast dynamics, enabling seamless integration with BODAS and other electronic systems.
4. Long-life bearings and wear-resistant rotary group, combined with standard pressure cut-off, extend service life under high-pressure duty and enhance system safety.
5. 100% interchangeability plus full operating-condition testing ensures exact match of mounting dimensions, ports and control characteristics with original Rexroth A4VG units, minimising downtime.

Application Areas

Designed for closed-circuit hydrostatic drives in mobile machinery, including crawler excavators, wheel loaders, pavers, rollers, agricultural and forestry equipment, and other mobile machines requiring bidirectional flow, precise control and high power density for travel and working functions.

Expert Maintenance Tips

1. Before installation, verify rotation direction, shaft spline and flange match; ensure precise alignment and avoid radial or axial overloads. Observe torque distribution when using through-drive.
2. Fully bleed the system and check boost pressure before first start-up. Use mineral-oil-based hydraulic fluid meeting Rexroth specifications; recommended cleanliness ISO 4406 18/16/13 or better.
3. Periodically monitor case temperature, leakage and high-pressure relief-valve settings. Keep the boost-circuit filter clean to prevent cavitation.
4. When changing filters and oil, inspect the swashplate, pistons and valve plate for wear. Perform preventive maintenance at the end of design life or when efficiency decreases to maximise hydraulic-system longevity.