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

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

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.

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.

Large displacement pumps need careful inlet design:

• Minimum absolute inlet pressure ≥ 0.8-1.0 bar (gauge ≈ −0.2 to −0.1 bar vacuum max)
• For sustained 1500 rpm or higher, consider a boost/charge pump providing 1.0-1.5 bar positive head
• Suction line requirements:
  • 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
• Tank outlet submerged ≥ 300 mm or above pump inlet

Cavitation signs: high-pitched whine, valve plate pitting, flow drop, early bearing failure

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.

• Connect one case drain port via a dedied 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

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.

• 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

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