A4VSO355EO2/30L-PPB25N00 German Rexroth A4VSO355 series piston pump

🔍 Model Code Breakdown

A4VSO  355   EO2  /   30   L   -   PPB25   N00
 │      │     │        │   │       │       └── No through-drive
 │      │     │        │   │       └── PPB25: SAE flanged / metric screws / Series 25 port plate
 │      │     │        │   └── L: Counter-Clockwise (CCW) viewed from shaft end
 │      │     │        └── 30: Series code (size group / design generation)
 │      │     └── EO2: Electro-hydraulic control, pilot-pressure dependent (external pilot port X required)
 │      └── 355 cm³/rev geometric displacement
 └── A4VSO: Open Circuit Variable Axial Piston Pump (Heavy-Duty Industrial)

💡 EO2 vs EO1:​ EO2 is a variant of the EO (electro-hydraulic pilot) control — typically differing in pilot piston area ratio, orifice size, or spring bias. Both require an external pilot pressure signal at port X to command swashplate angle. The exact pilot pressure vs. displacement characteristic should be verified in the A4VSO technical datasheet.

FAQ — Frequently Asked Questions (In-Depth)

Q1: What does "EO2" control mean? How is it different from DR, DFR, or LR2?

A:

• EO2 (Electro-Hydraulic / Pilot-Dependent):​ The pump has no internal spring setting a load-sense ∆p or fixed pressure. Displacement is governed entirely by pilot pressure Pₓ at port X​ (from a proportional reducing valve or electronic controller).

  • Pₓ = 0 (or below bias) → pump at min displacement / near zero delivery

  • Increasing Pₓ → swashplate angles proportionally → increases displacement up to max

  • A separate pressure limiter (mechanical DR element) is usually integrated to cap max pressure regardless of pilot signal.

• DR:​ Fixed-pressure compensator, local mechanical adjustment — no pilot, no LS.

• DFR / LR2:​ Hydraulic Load Sensing + Pressure Limiter with internal LS spring — needs LS line from valve bank.

• When to use EO2:​ You want electronic/discrete remote control of pump displacement or flow via a pilot valve, or integration into a digital/hybrid control architecture — not a standard LS system.

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.

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

• ❌ Running in reverse (Clockwise on an L pump):

  • Port plate alignment is directional → suction failure → cavitation/seizure

  • Internal lubrication channels are direction-specific → immediate loss of lube film

  • Damage occurs within seconds → total pump destruction

  • If rotation mismatches, either re-phase motor or order an "R" (clockwise) version.

Q3: What are the suction (inlet) requirements for this 355 cc pump?

A:​ Large displacement pumps need careful inlet design:

1. Minimum absolute inlet pressure ≥ 0.8–1.0 bar​ (gauge ≈ −0.2 to −0.1 bar vacuum max).

2. For sustained 1500 rpm or higher, consider a boost/charge pump​ providing 1.0–1.5 bar positive head.

3. Suction line:

   • Inner diameter ≥ DN65 (DN80 preferred)

   • Keep length < 1.5 m, minimize bends/restrictions

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

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

   Cavitation signs: high-pitched whine, valve plate pitting, flow drop, early 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 (e.g., gear pump for pilot/charge pressure), select a version with through-drive code such as K01, K02, K51, etc. For EO2 control you'll typically need a separate pilot pressure source anyway — plan accordingly.

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 blows out, valve plate distorts, bearings overheat → pump fails.

Q6: What drive motor power is required?

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

• Hydraulic power Pₕ = (355 × 10⁻⁶ × 350 × 1500) ÷ 600 ≈ 310 kW

• With ηₘₑcₕ ≈ 0.90 → shaft input ≈ 345 kW

➡ Recommended drive:​ 355 kW (≈475 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 pressure screw; run briefly to purge air from system.

5. Set pressure:​ Slowly turn DR adjustment screw clockwise to desired max pressure. EO2 pilot pressure from external valve will modulate displacement below that ceiling.

6. Lock & document:​ Tighten lock nut on DR adjuster; record settings.