Resealing a Bosch Rexroth A4VG variable pump without shipping it out for a rebuild is the job the 42 pages of repair manual RDE 92 003-21-R/01.06 are written for, across four nominal sizes of the series. Most of the book goes to exchanging external assembly groups on the A4VG 71, 90, 125 and 180: the shaft seal, positioning piston covers, low- and high-pressure valves, pressure cut-off, control valve O-rings, the backing pump and the complete control unit. A closing section walks you through checking charge pressure, high pressure, and mechanical and hydraulic zero stroke before the pump goes back into service. Run the high-pressure valves down to 150 Nm on NG 71 and 90 or 200 Nm on NG 125 and 180, then hold the control unit screws at 10.4 Nm. A weeping shaft seal can leave a machine parked for days. The PDF is bookmarked and text-searchable, so you reach the right page quickly and your machine can be moving again the same shift.
What's Inside This Repair Manual
| System | Pages | Key Topics |
|---|
| About This Manual | 2-6 | Contents, Validity of This Manual, Important Documents, Danger Labels and Pictograms |
| Safety | 7-10 | Basic Safety Information, Requirements on the Personnel |
| Product Description | 11-14 | Name Plate, Functional Description, Technical Data |
| Exchanging the Shaft Seal | 16-17 | Mounting Sleeve, Circlip, Shaft Seal, Drive Shaft |
| Exchanging Seals | 18-23 | Positioning Piston Covers, Low-Pressure Valve, High-Pressure Valve, Pressure Cut-Off, Control Valve, O-Rings |
| Exchanging the Backing Pump | 24-25 | Auxiliary Pump, Cover, O-Rings, Fixing Plugs, Port Plate |
| Exchanging the Control Unit | 26-32 | Control Unit, Gasket, O-Rings, Fastening Screws, Auxiliary Screws, Cover |
| Checking | 33-42 | Checking Low Pressure (Charge Pressure), Checking High Pressure, Checking the Mechanical Zero Stroke, Checking the Hydraulic Zero Stroke |
Quick Reference Specifications
| Specification | Value | Page |
|---|
| All Models |
| Control unit fastening screw (f) tightening torque | 10.4 Nm | p. 30 |
| Control unit assembly screw (f) tightening torque | 10.4 Nm | p. 30 |
| Low pressure valve tightening torque | 70 Nm | p. 23 |
| Pressure cut-off locking screw tightening torque | 35 Nm | p. 24 |
| Pressure cut-off sealing nut tightening torque | 25 Nm | p. 24 |
| Control valve tightening torque | 50 Nm | p. 25 |
| Pole tube tightening torque | 19 Nm | p. 28 |
| Control unit solenoid tightening torque | 5+1 Nm | p. 28 |
| Control unit fifth screw tightening torque | 10.4 Nm | p. 30 |
| A4VG 71, A4VG 90 |
| High-pressure valve tightening torque (NG 71-90) | 150 Nm | p. 24 |
| A4VG 125, A4VG 180 |
| High-pressure valve tightening torque (NG 125, 180) | 200 Nm | p. 24 |
| A4VG 90, A4VG 125, A4VG 180 |
| Control unit assembly screws tightening torque (NG 90-180) | 10.4 Nm | p. 32 |
