GSP2-A0S12AR-A0 UCHIDA REXROTH Hydraulic Gear Pump 12cc 250bar

Product Overview

The GSP2 Series is a UCHIDA REXROTH high-performance compact external gear pump product line. UCHIDA, a professional pump manufacturer widely recognized in construction machinery applications, was later acquired by REXROTH, forming the UCHIDA REXROTH brand.

The GSP2 Series features three-piece high-strength cast iron construction with pressure-balanced bushings, delivering a compact design with an excellent power-to-weight ratio—ideally suited for direct mounting to truck Power Take-Offs (PTOs) and other space-constrained mobile equipment. The series offers displacements from 4.5 to 52.8 cm³/rev, with rated operating pressures up to 25 MPa (250 bar) , and is widely used in construction machinery, forklifts, and hydraulic systems.

This page features three GSP2 Series models: GSP2-A0S12AR-A0 (12.1 cc/rev, right-hand rotation), GSP2-A0S16AR-A0 (16.2 cc/rev, right-hand rotation), and GSP2-BOX-14R-10-645-0 (BOX Series pilot pump, 14 cc/rev). These products are original UCHIDA REXROTH specification models, enabling direct form-fit-function interchangeability with original units—no modifications to piping or mounting interfaces required. Our replacement solutions strictly adhere to UCHIDA REXROTH technical standards and undergo 100% simulated in-service testing to ensure performance, reliability, and service life identical to OEM products.

Technical Specifications 

Model 1: GSP2-A0S12AR-A0

Applicable Model:

• GSP2-A0S12AR-A0

Model Code Breakdown (per UCHIDA REXROTH GSP2 Series naming convention):

• GSP2: UCHIDA REXROTH GSP2 Series External Gear Pump

• A0: Mounting flange specification (SAE standard flange)

• S12: Displacement specification (12.1 cm³/rev)

• AR: Rotation direction (A = standard configuration, R = Right-hand/Clockwise)

• A0: Shaft and port configuration

This Model Detailed Specifications:

• Geometric Displacement: 12.1 cm³/rev

• Rated Operating Pressure: 25 MPa (250 bar / 3,625 psi)

• Peak Pressure: 28 MPa (280 bar / 4,060 psi)

• Maximum Speed: 2,500 min⁻¹

• Minimum Speed: 500 min⁻¹

• Rotation Direction: Right-hand (clockwise, viewed from shaft end)

• Body Material: Three-Piece High-Strength Cast Iron

• Bearing Type: Pressure-Balanced Bushings

• Fluid Compatibility: Mineral Hydraulic Oil (HLP)

• Operating Temperature Range: -20°C to +80°C

• Seal Material: NBR / FKM (configuration dependent)

Model 2: GSP2-A0S16AR-A0

Applicable Model:

• GSP2-A0S16AR-A0

Model Code Breakdown (per UCHIDA REXROTH GSP2 Series naming convention):

• GSP2: UCHIDA REXROTH GSP2 Series External Gear Pump

• A0: Mounting flange specification (SAE standard flange)

• S16: Displacement specification (16.2 cm³/rev)

• AR: Rotation direction (A = standard configuration, R = Right-hand/Clockwise)

• A0: Shaft and port configuration

This Model Detailed Specifications (per UCHIDA REXROTH official documentation):

• Geometric Displacement: 16.2 cm³/rev

• Rated Operating Pressure: 25 MPa (250 bar / 3,625 psi)

• Peak Pressure: 28 MPa (280 bar / 4,060 psi)

• Maximum Speed: 2,500 min⁻¹

• Minimum Speed: 500 min⁻¹

• Rotation Direction: Right-hand (clockwise, viewed from shaft end)

• GD² Value (Single Pump): 2.1 × 10⁻⁴ kgf·m²

• Weight (Flange Mount Type): Approx. 5.5 kg

• Body Material: Three-Piece High-Strength Cast Iron

• Bearing Type: Pressure-Balanced Bushings

• Fluid Compatibility: Mineral Hydraulic Oil (HLP)

Model 3: GSP2-BOX-14R-10-645-0

Applicable Model:

• GSP2-BOX-14R-10-645-0

Model Code Breakdown (per UCHIDA GSP2-BOX Series naming convention):

• GSP2-BOX: UCHIDA GSP2-BOX Series Pilot Gear Pump

• 14: Displacement specification (14 cm³/rev)

• R: Rotation direction (Right-hand/Clockwise)

• 10: Series code

• 645: Specific configuration code

• 0: Version identifier

This Model Detailed Specifications (estimated based on GSP2 Series parameters):

• Geometric Displacement: Approx. 14 cm³/rev

• Rated Operating Pressure: 25 MPa (250 bar / 3,625 psi)

• Body Material: Three-Piece High-Strength Cast Iron

• Rotation Direction: Right-hand (clockwise, viewed from shaft end)

• Fluid Compatibility: Mineral Hydraulic Oil

• Operating Temperature: 30 – 90°C

Key Technical Advantages

1. Three-Piece High-Strength Cast Iron Construction — Superior Durability
The GSP2 Series is built with high-tensile, heavy-duty cast iron bodies and covers, providing superior structural rigidity compared to aluminum alternatives. This robust construction minimizes internal deflection and mechanical fatigue under high-pressure duty cycles, ensuring stable performance and extended service life in grueling work environments.

2. Side-Floating System — High Volumetric Efficiency
The GSP2 Series features a unique Side-Floating System that optimally maintains gear side clearance regardless of pressure changes, delivering high efficiency under all operating conditions. The side-floating system ensures optimal clearance control between gears and the housing across all operating conditions.

3. Pressure-Balanced Bushings — Superior Contamination and Thermal Shock Resistance
The GSP2 Series utilizes advanced pressure-balanced bushings instead of roller bearings, providing an increased bearing surface area. This design is inherently more tolerant of fluid contamination and thermal shock, maintaining high volumetric efficiency while protecting the pump from premature wear during intensive use.

4. Advanced Axial Compensation Technology — Low-Noise Operation
Equipped with pressure-balanced wear plates and advanced axial compensation technology, the GSP2 Series automatically optimizes internal clearances between the gear faces and the housing. This minimizes internal fluid bypass and friction, ensuring exceptional mechanical efficiency and consistent power delivery across all operating temperatures.

5. Modular Design — Flexible Installation and Configuration Options
The GSP2 Series offers a versatile range of displacements from 4.5 to 52.8 cc/rev, supporting standard SAE mounting options. With a unique dual-porting design that features both side and rear ports, it provides unmatched installation flexibility for cramped chassis environments and specialized mobile applications. The mating surface of the housing uses parallel pins for positioning, making it easy to disassemble, reassemble, and maintain.

Application Areas

• Construction Machinery: Excavators, loaders, crane hydraulic systems

• Forklifts: Forklift hydraulic systems

• Agricultural Equipment: Tractors, harvesters, and other agricultural machinery hydraulic systems

• Industrial Hydraulic Systems: Industrial hydraulic power units and automation lines

• Marine and Port Equipment: Ship deck cranes, hatch cover machinery hydraulic systems

• Mobile Equipment: Direct mounting to truck Power Take-Offs (PTOs)

Expert Maintenance Tips

1. Installation Precautions

• The GSP2 Series is a uni-directional rotation pump—verify that the system’s required rotation direction matches the pump’s identification marking before installation. All three featured models feature right-hand (clockwise) rotation.

• Ensure coaxial alignment between the pump and drive shaft; flexible couplings are recommended to avoid radial loads on the pump shaft.

• The mating surface of the housing uses parallel pins for positioning—pay attention to alignment during disassembly and reassembly.

• The GSP2-BOX Series is a pilot pump—special attention should be paid to correct piping connections during installation.

2. Fluid Management

• Use mineral hydraulic oils conforming to DIN 51524 standards (HLP).

• System fluid cleanliness must meet ISO 4406 ≦ Class 18/15/13 or higher.

• Operating temperature should be maintained within -20°C to +80°C.

• Recommended operating viscosity range is 10 – 300 mm²/s.

• Prime the pump by filling the housing with hydraulic fluid through the suction port before initial start-up. Never run the pump dry.

3. Start-Up & Commissioning

• Use jog start method for initial start-up; verify correct rotation direction before continuous operation.

• Allow the pump to run under no-load (low pressure) conditions for 2-3 minutes to purge air and ensure proper lubrication.

• Gradually increase to operating pressure (up to 250 bar) while monitoring noise, temperature, and system pressure for normal operation.

4. Routine Maintenance

• The GSP2 gear pump itself is maintenance-free; however, regular maintenance of the entire hydraulic system is essential for trouble-free pump operation.

• Inspect system fluid cleanliness and condition every 1,000-2,000 operating hours.

• Regularly replace return line filters and suction strainers to prevent contaminant ingress into the pump body.