FAQ - Frequently Asked Questions

Q1: What is the main difference between the A4VSO and A10VSO series?

A:​ The A4VSO is a heavy-duty industrial pump​ designed for a continuous operating pressure of 350 bar. It features a more robust bearing and construction, making it suitable for high-pressure applications like metal forming and injection molding. The A10VSO series is typically used for 280 bar in general mobile or industrial applications.

Q2: How does the DR control work?

A:​ DR is a pressure-compensating control. When system pressure is below the set value, the pump delivers full flow at maximum displacement (71 cc). Once pressure reaches the set point (adjusted via the screw on the control cover), the pump automatically reduces the swashplate angle, delivering only the minimal flow needed to maintain that pressure (to compensate for leakage), thereby saving energy.

Q3: Can I mount a gear pump on the through-drive of this model?

A:​ No.​ The suffix N00​ explicitly indicates no through-drive capability. The shaft does not protrude from the rear cover. If an auxiliary pump (e.g., a charge pump) is required, you must select a model with a through-drive suffix like K01 or K02.

Q4: What are the suction (inlet) requirements?

A:​ At 1500 rpm, the absolute pressure at the suction port (S) should be ≥ 0.8 bar (approx. -0.2 bar gauge/vacuum). If the speed is increased to 2200 rpm, the inlet must be pressurized​ (e.g., using a boost pump) to prevent severe cavitation and pump damage.

Q5: How do I adjust the pressure setting?

A:​ Turn the large hex screw​ on the DR control cover (usually with a locknut). Clockwise rotation increases the pressure.​ It is recommended to adjust under load with the system at the desired pressure. Always tighten the locknut securely after setting.

Q6: How should the case drain (L port) be connected?

A:​ The case drain port (L) must be connected directly to the reservoir via a dedicated line​ with zero backpressure​ (maximum allowable is typically 0.5 bar). A blocked or pressurized drain line will immediately damage the shaft seal, causing oil leakage.

Q7: Can I use Water Glycol (HFC) fluid with this pump?

A:​ Yes.​ The standard NBR seals are compatible with Water Glycol (HFC). However, note that the pump's rated pressure and speed may need to be derated. Refer to the Rexroth catalog for the specific fluid compatibility and derating tables.

Q8: What is the required fluid cleanliness level?

A:​ The requirement is very high. Fluid cleanliness must be at least NAS Class 9 (ISO 4406 18/16/13) or better. A 10 μm high-pressure filter with βₓ≥75​ is strongly recommended on the pressure line. Contamination is the primary cause of wear on the piston/slipper assembly.