AP2D18LV3RS7-883-2 Rexroth Uchida Piston Pump 2x18cc 280bar

Product Overview

The AP2D18LV3RS7-883-2 is a Rexroth Uchida (formerly Uchida-Rexroth, Japan) AP2D Series swashplate-type tandem variable displacement axial piston pump with a per-section displacement of 18 cm³/rev, total tandem displacement of 36 cm³/rev, maximum working pressure of 280 bar (4060 psi), maximum speed of 3500 rpm, total flow of approximately 93.6 L/min, and weight of approximately 19 kg. The pump features a single cylinder block dual-pump design in which a single drive shaft simultaneously drives two independent variable piston pump sections, providing dual-flow independent supply for mini excavator travel and work equipment circuits — the classic main pump configuration for 3–6 ton class mini excavator hydraulic systems.

The AP2D18 series is equipped with a Total Horsepower Control regulator, dynamically adjusting pump displacement so that total hydraulic system power consumption remains below the engine output power curve, effectively preventing engine lugging and stalling under heavy digging conditions while fully unleashing engine horsepower for increased machine speed and power output. This control characteristic enables the AP2D18LV3RS7-883-2 to maintain stable and efficient power matching under the frequent load changes of mini excavator operations.

The pump features a compact lightweight design in which the single cylinder block structure makes the overall tandem pump installation dimension approximately half that of conventional dual-pump solutions, particularly suitable for the limited engine compartment space of mini excavators. The SAE two-bolt mounting flange and standard splined shaft ensure 100% drop-in interchangeability with original Rexroth Uchida AP2D18 pumps. The AP2D18LV3RS7-883-2 is directly compatible with Kubota KX91-3, Komatsu PC30/PC35/PC45, CAT 303/E303.5 and other 3–6 ton mini excavators, installing directly without modifying mounting interfaces or plumbing layouts.

The AP2D Series covers AP2D12 (2×12 cm³/rev), AP2D16 (2×16 cm³/rev), AP2D18 (2×18 cm³/rev), AP2D21 (2×21 cm³/rev), AP2D25 (2×25 cm³/rev), AP2D28 (2×28 cm³/rev), and AP2D36 (2×36 cm³/rev) displacement sizes, offering multiple displacement ratings and control options within a shared mounting flange system to meet the hydraulic system configuration requirements of different tonnage excavators.

Every AP2D18LV3RS7-883-2 undergoes 100% simulated duty-cycle testing prior to shipment — covering pressure holding, flow output, control response, and internal leakage — ensuring complete drop-in interchangeability with original Rexroth Uchida products.

Technical Specifications

AP2D18LV3RS7-883-2 Main Model Specifications:

• Model: AP2D18LV3RS7-883-2

• Brand: Rexroth Uchida (formerly Uchida-Rexroth, Japan)

• Series: AP2D Series

• Pump Type: Swashplate-type tandem variable displacement axial piston pump

• Per-Section Displacement: 18 cm³/rev

• Total Tandem Displacement: 36 cm³/rev (2×18)

• Maximum Working Pressure: 280 bar (4060 psi)

• Maximum Speed: 3500 rpm

• Rated Speed: 2600 rpm

• Total Flow at Rated Speed: Approx. 93.6 L/min

• Total Flow at 2200 rpm: Approx. 79.2 L/min

• Control Type: Total Horsepower Control

• Direction of Rotation: Left-hand (L, counter-clockwise viewed from shaft end)

• Mounting Flange: SAE two-bolt flange

• Shaft Type: 13-tooth or 15-tooth splined shaft

• Housing Material: High-strength cast iron

• Weight: Approx. 19 kg

• Volumetric Efficiency: 92–94% (ISO VG46 clean oil, 20℃)

• Mechanical Efficiency: 88–90% (at rated pressure)

• Recommended Oil Viscosity: 22–46 cSt (ISO VG32–VG46)

• Critical Viscosity Range: 10–500 cSt

• Port Thread: G1/2″ (BSPP) or G3/4″ (BSPP)

• Fluid Compatibility: Mineral-based hydraulic oil

• Operating Temperature Range: 30–90 ℃

AP2D Series Same-Family Displacement Reference (nominal conditions):

• AP2D12: 12 cm³/rev per section, 24 cm³/rev total, max 2800 rpm, total flow 67.2 L/min, max power 16 kW, weight approx. 14 kg

• AP2D16: 16 cm³/rev per section, 32 cm³/rev total, max 2800 rpm, total flow 89.6 L/min, weight approx. 17 kg

• AP2D18: 18 cm³/rev per section, 36 cm³/rev total, max 2600 rpm, total flow 93.6 L/min, max power 19 kW, max torque 75.5 N·m, weight approx. 19 kg

• AP2D21: 21 cm³/rev per section, 42 cm³/rev total, max 2600 rpm, total flow 109.2 L/min, weight approx. 22 kg

• AP2D25: 25 cm³/rev per section, 50 cm³/rev total, max 2600 rpm, total flow 130 L/min, max power 36 kW, weight approx. 27 kg

• AP2D28: 28 cm³/rev per section, 56 cm³/rev total, max 2400 rpm, total flow 134.4 L/min, weight approx. 30 kg

• AP2D36: 36 cm³/rev per section, 72 cm³/rev total, max 2200 rpm, total flow 158.4 L/min, max power 37 kW, weight approx. 45 kg

Key Technical Advantages

1. Single Cylinder Block Tandem Design — Compact Structure and Dual-Flow Independent Supply

The AP2D18LV3RS7-883-2 employs Rexroth Uchida’s proprietary single cylinder block tandem pump design, in which a single drive shaft simultaneously drives two independent variable piston pump sections, delivering equal or unequal flow to the excavator travel and work equipment hydraulic circuits. Compared to conventional dual-pump solutions, this design reduces pump count and installation space requirements by approximately 50%, offering exceptional installation advantages within the compact engine compartments of mini excavators. The two pump sections share a common suction port and housing, simplifying plumbing layout and reducing potential leak points.

2. Total Horsepower Control — Intelligent Anti-Stall and Engine Power Utilization

The pump is equipped with a Total Horsepower Control regulator, dynamically adjusting total tandem pump displacement so that total hydraulic system power consumption remains below the engine output power curve. Under heavy digging, travel climbing, and other conditions, this control characteristic effectively prevents engine lugging and stalling while fully unleashing engine horsepower for increased machine speed and power output. Total horsepower control is the core energy-saving technology for mini excavator hydraulic systems, delivering significant power loss and fuel consumption reductions compared to fixed displacement pump systems.

3. Swashplate Variable Mechanism — Precise Flow Control and Fast Response

The AP2D18LV3RS7-883-2 employs a swashplate-type axial piston variable mechanism, achieving stepless displacement variation through swashplate angle adjustment. The pump delivers fast variable response, completing displacement adjustment within milliseconds under sudden load changes to maintain stable system pressure. The swashplate design combined with precision-machined piston assemblies and valve plates maintains high volumetric efficiency (92–94%) and low-noise operation across the full pressure range.

4. High-Speed Capability and Excellent Suction Performance

The AP2D18 achieves a maximum speed of 3500 rpm at 280 bar rated working pressure, with total flow of approximately 93.6 L/min at 2600 rpm rated speed. The pump delivers excellent suction performance with a single large suction port design, ensuring adequate suction at high speeds to prevent cavitation damage. The high-speed capability enables the pump to meet the flow demands of fast-cycle mini excavator operations, reducing work cycle times.

5. Exceptional Field Interchangeability and Broad Compatibility

The AP2D18LV3RS7-883-2 features SAE two-bolt mounting flange, splined shaft, and port layouts conforming to Rexroth Uchida AP2D Series standards, enabling drop-in interchangeability with same-series AP2D12, AP2D16, AP2D21 models. The pump is directly compatible with Kubota KX91-3, Komatsu PC30/PC35/PC45, CAT 303/E303.5 and other 3–6 ton mini excavators, installing directly without modifying mounting interfaces or plumbing layouts.

Application Areas

• Mini Excavators: Main hydraulic pump for Kubota KX91-3, Komatsu PC30/PC35/PC45, CAT 303/E303.5 and other 3–6 ton class mini excavators

• Small Excavators: Hydraulic power source for Kubota U30/U35, Bobcat 331/334/430, Case CX31/CX36 and other 2.5–4 ton excavators

• Sub-Compact Excavators: Takeuchi TB240/TB250, Yanmar VIO30 and other small excavator hydraulic systems

• Skid Steer Loaders: Main hydraulic pump for Bobcat S-series, Case SR-series skid steer loaders

• Small Construction Machinery: 3–5 ton small wheeled excavator and compact crawler loader hydraulic systems

• Municipal Engineering Equipment: Small municipal maintenance excavator and garden machinery hydraulic power sources

• Agricultural Machinery: Small agricultural excavator and orchard management machinery hydraulic systems

The AP2D18LV3RS7-883-2 is ideally suited for 3–6 ton mini excavator hydraulic systems requiring 280 bar working pressure and dual-flow independent supply — the classic configuration for Kubota, Komatsu, and CAT mini excavator main pumps.

Expert Maintenance Tips

1. Shaft Alignment and Coupling Requirements

Maintain concentricity between the pump shaft and drive shaft within 0.05 mm. Flexible couplings are strongly recommended to accommodate minor angular misalignment. The AP2D18LV3RS7-883-2 features an SAE two-bolt mounting flange and splined shaft — never strike the shaft end during installation to avoid damaging internal seals and bearings. The splined shaft (13-tooth or 15-tooth) engagement with the drive coupling should ensure sufficient spline engagement length. Tighten mounting flange bolts in diagonal sequence to the specified torque.

2. Pre-Start Pump Housing Filling Procedure (Mandatory)

Before starting the engine, the pump casing must be manually filled through its highest case drain port with 1.5–2.0 L of clean hydraulic oil until fluid overflows. Operating an axial piston pump dry — even for a few seconds — will cause the piston shoes to “weld” to the swashplate, causing immediate total pressure loss and irreversible damage. After filling, loosen the top air bleed port on the pump housing. Crank the engine with the fuel delivery disabled until a steady stream of bubble-free hydraulic oil flows out, then retighten the plug. Allow the machine to idle at low RPM with no load for 10 to 15 minutes to purge any remaining air from the system.

3. Total Horsepower Controller Commissioning

Commission the Total Horsepower Controller by verifying that the power setting matches the engine power output curve. The control start pressure is set according to system requirements; adjustment must be performed with the pump at full displacement and low operating pressure. During commissioning, first turn the control setting screw to the lowest pressure position, then gradually increase to the target pressure to avoid system pressure oscillation. In multi-pump systems, stagger the controller settings to ensure proper power distribution.

4. Hydraulic System Cleaning and Contamination Control

If replacing a pump that suffered internal mechanical failure, completely drain and clean the hydraulic oil reservoir, flush all circuit lines, and clean the oil cooler. Always replace return and suction filter elements prior to initial engine startup to prevent metal particles and contaminants from the failed pump from entering the new pump and causing secondary damage. The AP2D18 requires fluid cleanliness of ISO 18/16/13 (NAS Class 8) or better, using 10 μm pressure line filters.

5. Restart Procedure After Extended Shutdown

If the pump has been idle for more than 30 days, manually rotate the shaft several turns to verify free rotation before restarting. Check for abnormal leakage at the case drain port. After startup, operate at low pressure for 10–15 minutes until oil temperature reaches normal operating range before applying full load. Regularly inspect the splined shaft and drive coupling engagement during operation, ensuring sufficient keyway engagement length (at least 2/3 of the coupling width) to prevent spline wear. Periodically check the Total Horsepower Controller operation to ensure proper power limiting function.