Model Code Breakdown

• A10VSO: Axial piston variable pump (Open circuit).

• 100: Geometric displacement 100 cm³/rev.

• DRS: Control type (Pressure cut-off + Load Sensing).

• 32R: Series 32, Right-hand rotation.

• VPB12N00: Mounting and connection.

  • VPB12: SAE flange, suction and pressure ports opposite.

  • N00: No through-drive​ (This model cannot​ be used in a tandem configuration).

• S1439: Special manufacturing code (typically refers to a specific seal/bearing package or factory batch).

FAQ

1. How does DRS control work?

DRS is a combined Pressure cut-off + Load Sensing (LS)​ control.

• Pressure Cut-off: When system pressure reaches the set value (e.g., 280 bar), the pump automatically reduces its displacement to maintain constant pressure.

• Load Sensing (LS): The pump automatically senses the flow required by the actuator and delivers only the matching flow, maintaining a constant pressure differential (Δp, typically 10-20 bar) between the pump outlet and the load pressure. The advantage is energy savings and reduced heat generation from overflow.

2. Can this pump be used in a tandem configuration to drive a second pump?

No.

The N00​ code in the model number explicitly indicates that this pump has no through-drive. The drive shaft is enclosed within the rear cover and cannot extend to drive a second pump. If you need to mount a gear pump or another piston pump in series, you must select a variant with a through-drive code, such as VPB22U....

3. What is the most common installation mistake?

• Case Drain Port (L Port): Must be connected separately and directly​ to the tank, with a backpressure not exceeding 0.5-2 bar. It is strictly forbidden​ to connect it in series with the main return line (T port) or downstream of a return line filter. Doing so will cause shaft seal leakage and pump overheating.

• Suction Conditions: The absolute pressure at the suction port (S port) must not fall below -0.8 bar (vacuum) to prevent cavitation. It is recommended to use a short, large-diameter suction line, and monitor the pressure drop across the suction filter.

4. What could be the cause of excessive pump noise or overheating?

• Noise (Cavitation): Check for air leaks in the suction line, clogged suction filter, or oil temperature being too low (causing excessively high viscosity).

• Overheating: The most common causes are excessive case drain backpressure​ (undersized or restricted drain line) or prolonged operation at high pressure with small displacement (high power loss).

5. How do I adjust the pressure setting on the DRS control?

1. Locate the pressure adjustment screw on the control head (usually with a locknut, under a cap).

2. Always adjust with the system running under controlled conditions and a pressure gauge installed.

3. Loosen the locknut.

4. Turn the screw clockwise to increase​ pressure, counterclockwise to decrease.

5. Tighten the locknut and recheck the setting.

6. Do I still need an external relief valve?

Yes, absolutely.​ While the DRS control limits pressure, it is a control function, not a safety device. You must install a separate system safety relief valve​ (e.g., a DB/DBW type) in the main pressure line as a backup in case of control failure.

Disclaimer:​ For precise installation, commissioning, and maintenance, always refer to the official Rexroth technical documentation, specifically the data sheet RE 25700​ for the A10VSO Series.