A4VSO355LR2/30L-PPB13N00 Hydraulic piston pump, German Rexroth original A4VSO355

Model Code Decoded:

• A4VSO = Open‑circuit swashplate variable pump

• 355 = 355 cm³/rev displacement

• LR2 = Hydro‑mechanical constant power (hyperbolic) control

• /30 = Series 30

• L = CCW rotation

• P = Keyed shaft

• P = NBR seals

• B = ISO 4‑bolt flange

• 13 = Side ports with BSPP (G) threads (vs. 25 = SAE flange)

• N00 = No through‑drive

Frequently Asked Questions (FAQ)

Q1: What is the function of the "LR2" control and when should I choose it over DR or DFR1?

A: LR2 = Constant Power (Hyperbolic) Control.​ It senses pressure and automatically reduces displacement so that Pump Power ≈ p × Q ≈ constant. This prevents oversizing the electric motor — the motor can be sized for the rated power, not peak pressure × full flow.

• DR / DRG​ = Pressure compensator — holds constant pressure; pump flow goes to zero at pressure setpoint. Use for constant‑pressure systems.

• DFR1​ = Pressure + Flow (Load Sense) — maintains constant Δp for energy‑saving flow control. Use for variable‑flow load‑sensing systems.

• LR2 (this model)​ = Use when driving with a fixed‑power electric motor and you want to fully utilize motor HP without overload at high pressure.

⚠ LR2 does not​ give pressure‑holding like DR — system pressure can rise to the spring‑set limit if flow demand drops.

Q2: This model is "L" (counter‑clockwise). Can I use an "R" (clockwise) version instead?

A: Only if your electric motor or engine can be reversed. "L" = CCW when looking at the shaft end; "R" = CW. Pump body and port positions are the same, but rotation direction is not interchangeable​ once ordered. Always confirm motor rotation direction before specifying.

Q3: Is a case drain line required? How exactly should it be plumbed?

A: Yes — mandatory.​ The A4VSO has internal leakage that must be returned to tank:

• Connect the L‑port (case drain)​ directly to the tank, preferably above the oil level​ or via a standpipe ≤ 0.5 bar backpressure.

• Do NOT​ tee it into the suction line (risk of aeration and seal blow‑out).

• Route it to the tank before the suction strainer or to a clean‑side tank return header.

• Fill the pump case with clean hydraulic oil before first start‑up to prevent dry start damage.

Q4: What is the difference between port code "13" and "25"? What fittings do I need?

A:

• "13" (this model)​ = Side ports with metric BSPP (G‑thread)​ — Pressure B = G1½, Suction S = G2. Needs BSPP bonded‑seal adaptors or male G‑thread fittings.

• "25"​ = Side ports with SAE 4‑bolt flanges​ (Pressure = SAE Code 61 / 6000 psi, Suction = SAE Code 62 / 3000 psi). Needs SAE split‑flange halves + O‑rings.

Confirm your hose/hardline termination matches BSPP G‑threads before ordering.

Q5: Can this pump be used in a closed‑loop hydrostatic transmission?

A: No.​ The A4VSO series is designed exclusively for open‑circuit​ applications. For closed‑loop travel/winch drives, use Rexroth A4VG (variable) or A2FM/A6VM (motors) with a charge pump.

Q6: What are the critical installation & commissioning steps?

A:

① Filtration​ — Maintain system cleanliness ≤ NAS 9 (ISO 4406 code 17/15/12). Install 10 µm or finer full‑flow return filter.

② Suction Line​ — Keep short (<1.5 m if possible), generously sized (≥ 1.25× pump inlet area), with 100–150 mesh suction strainer. Min. inlet pressure 0.8 bar abs — use flooded suction if pump is above tank.

③ Alignment​ — Use a flexible coupling; pump shaft must not​ carry radial or axial loads from the motor.

④ Bleeding​ — Crack open the case drain or highest bleeder to purge air before running. Manually rotate shaft 2–3 turns if accessible.

⑤ Initial Run​ — Start at low pressure/no load for a few minutes to verify quiet operation, correct rotation, and case drain flow, then gradually bring to working pressure.