A11VLO260LRDS Rexroth Axial Piston Pump 260cc 350 bar

Product Overview

The A11VLO260LRDS/11R-NZD12N00 (Material No. R902233959) is the 260 cc-class core model within the Bosch Rexroth A11VLO series 1x of swashplate axial piston variable displacement pumps. The A11VLO series is Rexroth’s flagship platform for open-circuit mobile hydraulics, spanning displacements from 40 to 260 cm³/rev with a nominal pressure of 350 bar, peak pressure of 400 bar, and swashplate design for open-circuit hydrostatic drives.

A11VLO Series Core Features: Swashplate axial piston variable pump for open-circuit operation; output flow proportional to drive speed and displacement, steplessly variable between maximum and zero; self-priming capability with optional tank pressurization or charge pump; extensive control and regulation options with power setting externally adjustable (even during machine operation); 100% through-drive capable for mounting gear pumps and axial piston pumps up to the same nominal size.

Model Code Breakdown (for procurement and engineering reference):

• A11VLO: Rexroth swashplate axial piston variable pump, open circuit, with charge pump (impeller) version

• 260: Nominal size (NG), geometric displacement 260 cm³/rev

• LRDS: Constant power control (LR) + pressure cut-off (DS), composite control

• /11R: Series 11, clockwise rotation (viewed from shaft end)

• NZD12N00: N = mounting flange and port code; ZD = shaft configuration; 12 = design variant; N00 = additional configuration (without through drive)

• R902233959: Rexroth material number

LRDS Control Function Details:
The LRDS control combines two functions: LR (Constant Power Control, Leistungsregler) and DS (Pressure Cut-Off, Druckabschneidung). The LR controller ensures pump input power does not exceed the setpoint, automatically reducing displacement as system pressure rises to maintain P×Q constant. The DS pressure cut-off function rapidly reduces pump displacement to zero (maintaining only leakage compensation flow) when system pressure reaches the setpoint, maintaining system pressure at the set value. This control method is particularly suitable for mobile hydraulic systems requiring prime mover overload protection under variable load conditions while protecting the system from overpressure damage.

About A11VLO vs. A11VO: The A11VLO is the version with charge pump (impeller), enabling very high self-priming speeds through the integrated impeller charge pump, effectively preventing cavitation and ensuring stable pump operation at high speeds. The A11VO is the standard version without charge pump.

Drop-in Replacement Advantage: Manufactured to exact Rexroth OEM specifications, this pump achieves complete drop-in interchangeability with the original A11VLO series for SAE J744 4-hole mounting flange, shaft dimensions, SAE main port layout, and LRDS control module interface. Every pump undergoes 100% simulated load testing prior to shipment, validating 350 bar pressure loading, LRDS composite control response, and volumetric efficiency under conditions replicating real-world duty cycles.

Technical Specifications 

A11VLO260 Series General Specifications:

• Series: Rexroth A11VLO Series 1x (Open Circuit, Swashplate Design)

• Nominal Size: NG 260

• Geometric Displacement (Vg max): 260 cm³/rev

• Geometric Displacement (Vg min): 0 cm³/rev

• Nominal Pressure: 350 bar (continuous)

• Peak Pressure: 400 bar (intermittent)

• Maximum Speed (at Vg max): 1800 rpm

• Maximum Speed (at Vg ≤ Vg max): 2300 rpm

• Minimum Speed: 500 rpm

• Maximum Flow (nmax, Vg max): 468 L/min

• Maximum Power (Δp = 350 bar): 273 kW

• Maximum Torque (Vg max, Δp = 350 bar): 1448 N·m

• Volumetric Efficiency: ≥94% (rated conditions)

• Control Type: LRDS — Constant Power Control + Pressure Cut-Off

• Rotation: Clockwise (viewed from shaft end, R code)

• Mounting Flange: SAE J744 4-hole flange

• Shaft: ANSI B92.1a–1976 splined shaft (for single pump)

• Housing Material: High-strength cast iron

• Seal Material: NBR, suitable for mineral oil-based hydraulic fluid

• Fluid Cleanliness: ISO 4406 18/15/12 or better

• Operating Temperature Range: -25°C to +115°C (housing)

• Working Fluid Temperature Range: 30–90°C

• Case Drain Pressure: Normal <2 bar, maximum 0.8–30 bar

• Weight: Approx. 125 kg

• Through Drive Capability: 100% through drive, supports mounting of subsequent pumps up to the same nominal size

Model A11VLO260LRDS/11R-NZD12N00 Configuration:

• Model Code: A11VLO260LRDS/11R-NZD12N00

• Material Number: R902233959

• Control Type: LRDS — Constant Power + Pressure Cut-Off

• Rotation: Clockwise (viewed from shaft end, R code)

• Series: 11

• Configuration: NZD12N00 shaft and port configuration

A11VLO Series Displacement Size Reference:

• A11VLO130: 130 cm³/rev, max speed 2100 rpm, max flow 273 L/min, max power 159 kW, weight approx. 66 kg

• A11VLO145: 145 cm³/rev, max speed 2200 rpm, max flow 319 L/min, max power 186 kW, weight approx. 76 kg

• A11VLO190: 190 cm³/rev, max speed 2100 rpm, max flow 405 L/min, max power 236 kW, weight approx. 95 kg

• A11VLO260: 260 cm³/rev, max speed 1800 rpm, max flow 468 L/min, max power 273 kW, weight approx. 125 kg

Key Technical Advantages

1. LRDS Constant Power and Pressure Cut-Off Composite Control
The A11VLO260LRDS/11R-NZD12N00 is equipped with the LRDS composite control module, integrating constant power control (LR) and pressure cut-off (DS) functions into a single unit. The LR controller’s core is precise control based on a power setting curve — as system pressure rises, the LR controller automatically reduces pump displacement, ensuring pump input power never exceeds the setpoint (P×Q=constant), achieving precise matching between hydraulic system power and prime mover output power while effectively preventing engine overload stall. The DS pressure cut-off function rapidly reduces displacement to zero when system pressure reaches the setpoint, maintaining only leakage compensation flow to protect the system from overpressure damage. This composite control method enables optimal energy utilization and overload protection across the entire operating range.

2. Swashplate Design with High Power Density
The A11VLO series employs a swashplate axial piston rotary group design where swashplate inclination angle determines piston stroke and displacement. The 260 size delivers maximum power of 273 kW, maximum torque of 1448 N·m, and maximum flow of 468 L/min at 350 bar nominal pressure, achieving a power density of approximately 2.2 kW/kg, leading its displacement class. The swashplate configuration offers compact axial dimensions suitable for space-constrained mobile hydraulic applications. Output flow is steplessly variable between maximum and zero, with smooth flow direction changes as the swashplate passes through the neutral position.

3. Integrated Charge Pump (Impeller) with High Self-Priming Speed
The “O” in A11VLO indicates the version with charge pump (Impeller). The integrated impeller charge pump significantly improves the pump’s self-priming capability, effectively preventing cavitation and enabling stable operation at high speeds. The charge pump provides stable boost pressure, ensuring the piston slippers remain in contact with the valve plate, extending pump service life.

4. 100% Through Drive and Modular System Expansion
The A11VLO series supports 100% through drive, allowing direct mounting of gear pumps or same-size axial piston pumps on the rear of the main pump for single-motor multi-pump compound hydraulic systems. The through-drive end shaft specification is SAE J744 101-2 (B) flange with 7/8 inch splined shaft hub. Modular control designs enable field conversion and upgrade, with standardized mounting interfaces (SAE J744 4-hole flange) requiring no adaptation for replacement, significantly reducing equipment downtime.

5. High Volumetric Efficiency with Low Energy Consumption
The A11VLO260 employs precision-ground pistons and cylinder bores with micron-level clearances, and a precision port plate design, achieving volumetric efficiency of ≥94%. The advanced swashplate design and manufacturing processes enable the pump to save more energy than other pump types when conveying the same flow rate. The LRDS control method achieves on-demand flow delivery, effectively reducing throttling losses and system heat generation, improving overall energy efficiency.

6. High-Strength Cast-Iron Housing with Wide Temperature Adaptability
The pump body is precision-cast from high-strength cast iron, with the material’s damping characteristics effectively suppressing structural vibration and fluid-borne noise. The working fluid temperature range is 30–90°C, and the housing operating temperature range reaches -25°C to +115°C, accommodating conditions from cold outdoor environments to high-temperature industrial applications. The drive shaft features high rigidity design with a Z-type torsional stiffness of 686465 Nm/rad, ensuring stable operation at high speeds.

Application Areas

• Concrete Pump Trucks: Main hydraulic pump systems (A11VLO260 is widely used in concrete pump trucks)

• Concrete Wet Shotcrete Machines: Hydraulic main pump systems for high-dust, high-intensity continuous operation

• Excavators: Medium to large excavator main hydraulic systems (A11VLO series is a core hydraulic pump for excavators)

• Rotary Drilling Rigs: Main hydraulic pump systems for high-torque drilling operations

• Tunnel Boring Machines: Thrust and cutterhead drive hydraulic systems

• Cranes: Truck crane hydraulic systems, crawler crane main hydraulic pumps

• Hydraulic Drilling Rigs: High-power hydraulic transmission systems

• Aluminum Extrusion & Casting: Industrial hydraulic power unit main pumps

Expert Maintenance Tips

1. Hydraulic Fluid Cleanliness
The A11VLO series LRDS control spool operates with extremely tight clearances and is highly sensitive to particulate contamination. System fluid cleanliness must meet ISO 4406 18/15/12 or better. Recommended fluids are ISO VG46 anti-wear hydraulic oils (HLP mineral oil). Install a 10 μm absolute-rated filter element at the pump inlet. Replace elements at 500 hours after first commissioning, then every 1,000 operating hours or 6 months, whichever comes first.

2. LRDS Composite Controller Commissioning Procedure
The LRDS controller should be adjusted in the following sequence: first set the LR constant power controller’s power control curve start point, determining at what pressure the pump begins reducing displacement; then set the DS pressure cut-off value to ensure system pressure does not exceed the 350 bar nominal pressure. Mechanical adjustment of the LR power control start point should be performed with the pump at neutral (zero displacement). Adjust only with the system at zero load. Rotate the adjustment screw slowly and verify stable pressure gauge readings before proceeding. Power setting is externally adjustable even during machine operation.

3. Case Drain Line Requirements
The case drain line must return directly to the reservoir. Maximum permissible back pressure is 2 bar (0.2 MPa), with a maximum allowable range of 0.8–30 bar. The drain outlet must terminate below oil level at all times to prevent air ingestion. The drain line diameter must not be smaller than the pump case drain port size. For 260 cc class large displacement pumps, case drain flow is substantial — drain line design must fully account for flow demand to avoid excessive case pressure from pipe resistance.

4. Pre-Start Priming and Air Bleeding
Before first start, fill the pump housing with clean hydraulic fluid through the case drain port. After installation, turn the drive shaft by hand several revolutions to confirm free rotation without binding. Position the control at neutral (zero displacement) and run at low speed for 5–10 minutes. Verify continuous bubble-free flow from the case drain. Only then apply load.

5. Splined Shaft and Coupling Maintenance
The A11VLO260 uses an ANSI B92.1a–1976 standard splined shaft (for single pump). Ensure drive shaft alignment during installation, employing a flexible coupling. Apply appropriate grease to the spline connection to prevent fretting wear. Inspect coupling alignment and spline wear at 500 hours after first commissioning, then recheck every 2,000 operating hours.

6. Through Drive End Maintenance
If equipped with through drive, regularly inspect rear pump mounting bolt tightness and spline connection wear. The through-drive end bearing is lubricated by the pump’s internal case drain circuit — no additional maintenance required. However, the rear pump’s power demand must not exceed the through-drive rated torque capacity (100% through drive). Inspect through-drive end bolt torque at 500 hours after first commissioning, then recheck every 2,000 operating hours.