R910945253 AA10VSO140DFR1/31R-VPB12N00 German Rexroth Variable Axial Piston Pump

FAQ - Frequently Asked Questions

Q1: What is the main difference between DFR and DFR1 control?

A:​ Both are Load Sensing (LS) + Pressure Limiting (DR)​ controls. The key difference is that DFR1​ has an internally plugged X port​ (external control line connection). This makes it simpler for standard applications where remote pressure control via an external pilot line is not needed. The pressure cutoff is adjusted directly on the pump's control cover.

Q2: How does the DFR1 control work in practice?

A:​ It operates in two stages:

• Flow Control (Load Sensing):​ The pump automatically adjusts its displacement to maintain a constant Δp (pressure differential)​ between the pump outlet (P) and the load sense signal (LS), typically ~14 bar. This delivers only the flow demanded by the system.

• Pressure Limiting:​ If the system pressure reaches the set value on the DR control cover, the pump de-strokes to maintain that maximum pressure, preventing overload.

Q3: Why is the case drain important and how should it be plumbed?

A:​ This pump has two case drain ports. You must connect one​ of them directly to the tank (reservoir) with a dedicated line. The second port must be plugged. The drain line must have zero backpressure​ (max 0.5 bar) to prevent damage to the shaft seal. Do not connect both drains to different points.

Q4: Can I use this pump with a diesel engine?

A:​ Yes, it is common in mobile machinery. Ensure:

• Rotation is correct​ (Clockwise 'R' when viewed from the shaft end).

• The engine's SAE housing may require an adapter flange (this pump has an ISO flange).

• Check that the engine's torsional vibration levels are within Rexroth's limits to avoid premature failure.

Q5: What is the maximum recommended speed?

A:​ The standard nominal speed for the 140 size is 1500 rpm. While the catalog may list a maximum of 1800-2000 rpm, running at higher speeds requires excellent suction conditions (pressurized inlet > 0.8 bar abs) and may reduce service life. Always consult the performance curves for your specific viscosity.

Q6: What does the "V" in the code mean for seals?

A:​ V​ stands for FKM (Viton)​ seals. This is suitable for a wider range of fluids, including certain biodegradable oils (HEES) and high-temperature applications. If you are using standard mineral oil, NBR (code 'P') is also acceptable, but 'V' offers better chemical resistance.