A4VSO355EO1/30L-PPB25N00 Rexroth hydraulic pump, German made piston pump

FAQ — Frequently Asked Questions

Q1: What does "EO1" control mean on an A4VSO pump?

A:​ EO1​ is an electro-hydraulic control version​ — typically a load-sensing / pressure-limiting control that accepts an external pilot pressure signal (and optionally an electrical command via a separate proportional valve or Rexroth RC/VT type controller). Unlike DFR (built-in spring-controlled LS), EO1 relies on an external pilot circuit to define the pump's displacement demand. The exact function (LS-only, LS+DR, remote pressure) depends on the pilot valve/block used with it.

Q2: The rotation code is "L" (30L) — what does that mean practically?

A:​ "L" = Counter-Clockwise​ when viewed from the drive shaft end. This is the opposite of the more common "R" (Clockwise). The pump must be driven in this direction — running it in reverse will cause immediate failure due to loss of lubrication and improper suction. Always verify your prime mover / coupling rotates counter-clockwise from the shaft side.

Q3: What are the suction (inlet) requirements for this large displacement pump?

A:​ With a 355 cc displacement, proper inlet conditions are critical:

• At 1500 rpm, inlet absolute pressure should be ≥ 0.8–1.0 bar​ (supercharge preferred for sustained high speed).

• For speeds >1500 rpm, a boost pump​ is strongly recommended to prevent cavitation.

• Keep inlet line short, generously sized, and avoid restrictions. Use a 149 µm (100 mesh) suction strainer.

Q4: Can I mount an auxiliary pump (gear pump) on the rear?

A:​ No.​ The suffix N00​ indicates no through-drive shaft. The rear of the pump housing is blanked. If you need a through-drive for a charge / pilot gear pump, select a version with a through-drive code such as K01, K02, etc.

Q5: How should the case drain (L port) be handled?

A:​ Connect one case drain port​ directly to the tank with a dedicated line — zero backpressure​ (max 0.5 bar). The second drain port must be plugged. The case drain line should be positioned above the tank oil level or looped to prevent air ingestion. A blocked drain = shaft seal failure.

Q6: What drive motor power is required?

A:​ At 1500 rpm, 350 bar, and 355 cc:

• Theoretical hydraulic power ≈ (355 × 10⁻⁶ × 350 × 1500) / 600 ≈ 310 kW

• Including mechanical losses (~90%), input power ≈ 345 kW

  Recommend a 355 kW (≈475 HP)​ prime mover with adequate starting torque reserve for 400 bar peak conditions.

Q7: Is the standard NBR seal okay for water glycol (HFC) or phosphate ester (HFD)?

A:​ Standard NBR is compatible with HFC (water glycol) with pressure/temp derating. It is NOT compatible with HFD (phosphate ester)​ — for HFD you need FKM (Viton) seals, which would be a custom order (typically with /V suffix on the shorter code). Confirm with Rexroth if your fluid is not mineral oil.