A4VSO250DRG/30L-PPB13N00 Rexroth Germany original A4VSO250 series hydraulic piston pump

A4VSO250DRG/30L-PPB13N00 — Variable Displacement Axial Piston Pump (A4VSO Series, Open Circuit)

⚠️ Important:​ A4VSO is a hydraulic pump (not a motor)​ for mineral oil hydraulic systems only. It cannot pump water and must not be run dry or in reverse rotation.

📋 Parameter Specification Table

🔍 Model Code Br

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A4VSO  250   DRG  /   30   L   -   PPB13   N00
 │      │     │        │   │       │       └── No through-drive
 │      │     │        │   │       └── PPB13: SAE flanged / metric screws / Series 13
 │      │     │        │   └── L: Counter-Clockwise (CCW) viewed from shaft end
 │      │     │        └── 30: Series code (size group / design generation)
 │      │     └── DRG: Pressure Compensator + Remote Pilot Port X (local adj. sets max; pilot can lower it)
 │      └── 250 cm³/rev geometric displacement
 └── A4VSO: Open Circuit Variable Axial Piston Pump (Heavy-Duty Industrial)

FAQ — Frequently Asked Questions (In-Depth)

Q1: What is "DRG" control and how is it different from plain "DR" or "DFR"?

A:

• DR (basic):​ Pressure compensator with local mechanical adjustment only. Set screw determines the cutoff pressure; no external influence possible.

• DRG (this model):​ Same pressure compensator PLUS a pilot port (X). The local screw sets the maximumpressure; an external pilot signal (e.g., from a hand pump, pneumatic pilot valve, or proportional reducing valve) can reduce the effective setting​ — i.e., pilot pressure at X subtractsfrom the local spring setting. Useful when you need to change the pump's pressure cap electrically/pneumatically or from a remote station.

• DFR / LR2:​ Adds Load Sensing (LS)​ function — pump tracks valve-bank LS signal with a fixed ∆p. DRG has no LS; it's purely a remotely-influenceable pressure limiter.

• When to choose DRG:​ You need a simple pressure-limited pump but also want the ability to remotely lower/modulate the pressure setpoint (e.g., energy save mode, multi-stage pressure system) without a full LS setup.

Q2: The rotation code is "L" (30L) — how do I verify and what if it's wrong?

A:

• L = Counter-Clockwise (CCW):​ Face the drive shaft end (coupling side looking into the pump); the shaft must rotate counter-clockwise.

• Check motor rotation arrow or perform a brief jog test before final coupling.

• ❌ Running in reverse on an L pump:

  • Port plate suction/pressure windows are asymmetrical → suction failure → cavitation/seizure

  • Internal lubrication galleries are directional → immediate loss of lube film

  • Damage is near-instantaneous → total pump destruction

  • Correct by re-phasing motor or ordering an "R" (clockwise) version — never force reverse run.

Q3: What are the suction (inlet) requirements for this 250 cc pump?

A:

1. Minimum absolute inlet pressure ≥ 0.8 bar​ (gauge ≈ −0.2 bar vacuum max).

2. For sustained 1500+ rpm, a boost pump​ providing 1.0–1.5 bar positive head is recommended for margin.

3. Suction line:

   • Inner diameter ≥ DN50 (DN65 preferred)

   • Length as short as possible (< 1.5 m), minimize elbows

   • 100 mesh (149 µm) suction strainer with < 0.05 bar pressure drop

4. Tank outlet submerged ≥ 300 mm or above pump inlet.

   Cavitation symptoms: high-pitched whine, valve plate pitting, flow drop, premature bearing failure.

Q4: Can I mount a gear pump on the rear for charge/pilot pressure?

A:​ No.​ The suffix N00​ = no through-drive shaft. Rear housing is blanked. If you need a through-drive for an auxiliary pump, select a version with through-drive code such as K01, K02, K51, etc. For DRG you typically still need a separate pilot pressure source for port X if remote control is used.

Q5: How must the case drain (L port) be plumbed?

A:

• Connect one case drain port​ via a dedicated line directly to the tank​ (above oil level or looped to prevent siphon).

• Backpressure ≤ 0.5 bar (ideally 0 bar). Plug the unused drain port.

• ❌ Never:​ block it, tie it into a pressurized return line, or share a small-bore return with other valves.

• Result of neglect:​ Housing pressurizes → shaft seal blowout, valve plate distortion, bearing overheating → pump fails.

Q6: What drive motor power is required?

A:​ At 350 bar / 1500 rpm / full displacement:

• Hydraulic power Pₕ = (250 × 10⁻⁶ × 350 × 1500) ÷ 600 ≈ 219 kW

• With ηₘₑcₕ ≈ 0.90 → shaft input ≈ 243 kW

➡ Recommended drive:​ 250 kW (≈335 HP)​ electric motor, S1 duty, with adequate starting torque for 400 bar peak. Avoid prolonged operation below ~750 rpm minimum continuous speed.

Q7: Are NBR seals OK with HFC or HFD fluids?

A:

• ✅ HFC (Water Glycol):​ NBR acceptable with pressure/temperature derating per Rexroth (typically ×0.8 pressure factor, watch Tmax).

• ❌ HFD (Phosphate Ester):​ NBR will swell → must specify FKM (Viton) seal version​ (/V suffix or explicit FKM option).

• Standard mineral oil (HL/HLP) → no issue with NBR.

Q8: What are the key commissioning steps?

A:

1. Fill & bleed:​ Loosen case drain and HP port bleed screw. Hand-rotate shaft while filling till oil flows bubble-free.

2. Verify case drain line​ is open to tank.

3. Jog-test rotation​ — confirm CCW (L), no abnormal noise.

4. Low-pressure run-in:​ Back off DR adjustment screw (minimum pressure); run briefly to purge air from system and lines.

5. Set pressure:​ Slowly turn DR screw clockwise to desired max pressure. If using pilot port X, verify remote lowering function.

6. Lock & document:​ Tighten lock nut on DR adjuster; record both local and (if applicable) pilot-influenced settings.