QXM22-008N130 Bucher Gear Unit | 8cc 400 bar Pump/Motor

Product Overview

The QXM22-008N130, QXM22-008N350, QXM23-005N130, and QXM23-006N130 are representative models of the Swiss BUCHER QXM series internal gear units. The QXM series is an extension of the BUCHER QX internal gear pump series and is suitable for operation as both a hydraulic pump and a hydraulic motor. Thanks to the completely symmetrical design, these units are capable of 4-quadrant operation (driving and braking in both directions of rotation), making them suitable for a wide range of applications in both industrial and mobile hydraulics.

The QXM series features a non-compensated internal gear design, consisting of a fixed, single-piece pinion shaft and internal gear supported by a hydrodynamic oil film. This robust construction allows it to handle extreme pressure peaks and high viscous fluids without performance degradation. Based on BUCHER’s proven QX 5th generation internal gear pump technology—validated over decades of global service—the series delivers extremely low noise and extremely low pressure pulsation while providing high-pressure capability up to 400 bar.

Engineered as a direct OEM-replacement solution, these models fully comply with BUCHER original design standards and SAE mounting interface specifications, offering 100% direct interchangeability with OEM units. Every unit undergoes 100% workload simulation testing prior to shipment, rigorously validating pressure retention, volumetric efficiency, and internal leakage performance to meet or exceed OEM standards.

Model Code Breakdown 

• QXM — Series: BUCHER Internal Gear Unit (Pump/Motor)

• 22 / 23 — Frame size: QXM2 Series (displacement 5–16 cc/rev)

• 008 / 005 / 006 — Displacement code: 8.0 / 5.0 / 6.3 cc/rev respectively

• N — Seal and configuration code (standard NBR seals)

• 130 / 350 — Specific configuration and pressure level code (shaft, port specifications, etc.)

Technical Specifications 

QXM22-008N130 / QXM22-008N350

• Model: QXM22-008N130 / QXM22-008N350

• Brand: BUCHER (Switzerland)

• Series: QXM Internal Gear Unit (Pump/Motor)

• Frame Size: QXM22 (QXM2 Series)

• Displacement: 8.0 cc/rev

• Continuous Operating Pressure: 320 bar

• Peak Pressure (Intermittent): 400 bar

• Maximum Speed (Pump Mode): 4000 rpm

• Maximum Speed (Motor Mode): 6000 rpm

• Minimum Recommended Speed: 1200 rpm (reference from QXM23-006)

• Rotation Direction: Bi-directional (4-quadrant operation)

• Mounting: SAE 2-Bolt / 4-Bolt flange

• Circuit Type: Open circuit & Closed circuit

• Noise Level: < 75 dB(A)

• Volumetric Efficiency: Up to 98%

• Compatible Fluids: Mineral oil, HFC (water-glycol), HFD (fire-resistant)

• Viscosity Range: 10 – 300 cSt (Standard)

• Certifications: ATEX 2, ABS, DNV, GL, LR, NK, etc.

• Housing Material: High-strength cast iron

QXM23-005N130

• Model: QXM23-005N130

• Brand: BUCHER (Switzerland)

• Series: QXM Internal Gear Unit (Pump/Motor)

• Frame Size: QXM23 (QXM2 Series)

• Displacement: 5.0 cc/rev

• Continuous Operating Pressure: 320 bar

• Peak Pressure (Intermittent): 400 bar

• Maximum Speed (Pump Mode): 4000 rpm

• Maximum Speed (Motor Mode): 6000 rpm

• Rotation Direction: Bi-directional (4-quadrant operation)

• Mounting: SAE 2-Bolt / 4-Bolt flange

• Circuit Type: Open circuit & Closed circuit

• Noise Level: < 75 dB(A)

• Volumetric Efficiency: Up to 98%

QXM23-006N130

• Model: QXM23-006N130

• Brand: BUCHER (Switzerland)

• Series: QXM Internal Gear Unit (Pump/Motor)

• Frame Size: QXM23 (QXM2 Series)

• Displacement: 6.3 cc/rev

• Continuous Operating Pressure: 320 bar

• Peak Pressure (Intermittent): 400 bar

• Maximum Speed (Pump Mode): 4000 rpm

• Maximum Speed (Motor Mode): 6000 rpm

• Minimum Recommended Speed: 1200 rpm

• Rotation Direction: Bi-directional (4-quadrant operation)

• Mounting: SAE 2-Bolt / 4-Bolt flange

• Circuit Type: Open circuit & Closed circuit

• Noise Level: < 75 dB(A)

• Volumetric Efficiency: Up to 98%

Key Technical Advantages

1. Pump/Motor Dual Function – 4-Quadrant Operation & Energy Recovery
The QXM series internal gear units can operate as both a hydraulic pump and a hydraulic motor. Thanks to the completely symmetrical design, they support 4-quadrant operation (driving and braking in both directions of rotation), enabling control of the full cylinder stroke while recovering energy during the lowering process. For example, the unit works as a pump during a lifting process and can then work as a motor during the lowering process to feed energy back into the system. This makes it ideal for energy recovery systems and hybrid applications.

2. Ultra-Low Noise & Ultra-Low Pulsation Operation
The QXM series features a non-compensated internal gear design with gear tooth profiles optimized through CAE. Compared to external gear or piston motors, the internal gear profile ensures significantly lower pulsation and noise, often eliminating the need for expensive sound insulation. Noise levels are below 75 dB(A) .

3. Superior High-Pressure Capability
Continuous operating pressure of 320 bar with peak pressures up to 400 bar. This high-pressure capability allows it to handle applications typically reserved for piston units. The robust non-compensated construction withstands extreme pressure peaks without performance degradation.

4. High Volumetric Efficiency & Long Service Life
Volumetric efficiency reaches up to 98%. The simple design with few moving parts and large plain bearings ensures an exceptionally long service life. Long-term reliability is maintained even when using fire-resistant fluids (HFC).

5. Wide Media & Wide Operating Condition Adaptability
Compatible with mineral oil, HFC (water-glycol), HFD (fire-resistant), and various hydraulic fluids. Suitable for both fixed-speed and variable-speed drives. Viscosity range of 10–300 cSt. Stable operation at both low and high speeds.

6. Comprehensive International Certifications
The QXM series carries ATEX 2 explosion protection certification, along with ABS, DNV, GL, LR, NK, and other international marine classification society certifications, making it suitable for industries with stringent safety and reliability requirements.

7. 100% Factory Tested & Direct Interchangeability
Every unit undergoes 100% workload simulation testing prior to shipment, covering pressure retention verification, internal leakage detection, and flow validation. Fully compliant with BUCHER original design standards and SAE mounting interface specifications, with flange dimensions, shaft specifications, and mounting interfaces identical to OEM units—direct drop-in replacement with zero modifications required.

Application Areas

The QXM series internal gear units are widely used in the following equipment and systems:

• Injection Molding Machines: Stable, low-noise hydraulic power

• Hydraulic Presses: Precise pressure and position control

• Flight Simulators: High-precision hydraulic drives

• Fan Drives: Cooling systems in mobile machinery (low noise is critical)

• Wind Turbines: Pitch control and braking systems

• Elevator/Lift Drives: Energy recovery applications

• Winch Drives: Marine and forestry winches requiring smooth low-speed control

• Marine Industry: Marine hydraulic systems

• Cranes and Lifting Systems

• Plastic Machinery

• Energy Recovery Systems: Hybrid excavators, forklift mast lowering energy recovery

Expert Maintenance Tips

1. Model Confirmation
QXM22-008N130 and QXM22-008N350 share the same QXM22 frame and 8 cc/rev displacement, differing only in suffix configuration codes (130 vs 350). QXM23-005N130 (5 cc/rev) and QXM23-006N130 (6.3 cc/rev) are different displacement options within the QXM23 frame. Before installation, confirm the correct model based on system flow/torque requirements and verify the complete model code on the unit nameplate.

2. 4-Quadrant Operation Considerations
The QXM series supports 4-quadrant operation and can function as either a pump or a motor. In energy recovery applications, the unit switches between pump mode and motor mode. System design must ensure that control logic correctly recognizes and accommodates both operating modes.

3. Installation Precautions

• Thoroughly clean the mounting flange and shaft mating surfaces before installation to ensure no debris remains

• Mounting options include SAE 2-Bolt or SAE 4-Bolt flange

• Use BUCHER-specified torque values for mounting bolts—avoid over-tightening which may cause distortion of the cast iron housing

• Ensure correct connection of inlet, outlet, and drain ports—QXM units are typically equipped with a dedicated drain port

4. First Start-Up and Bleeding

• Before first start-up, must fill the unit with hydraulic oil through the inlet port—never start dry

• After start-up, run at low speed with no load for 2–3 minutes to ensure complete air evacuation from the system

• Minimum inlet pressure: 1 bar absolute

• Check for abnormal noise or leakage—internal gear units are particularly sensitive to cavitation

5. Fluid and Filtration

• Use high-quality anti-wear hydraulic oil compliant with DIN 51524 standards

• Maintain viscosity within 10 – 300 cSt range

• QXM series is compatible with mineral oil, HFC (water-glycol), and HFD (fire-resistant fluids)

• Maintain system oil cleanliness to ISO 4406 18/15 or better

• Regularly replace return line filters to prevent contaminants from entering the unit

6. Periodic Maintenance

• Check mounting bolt torque every 1,000 operating hours

• Regularly monitor system operating pressure—not to exceed 320 bar continuous (400 bar peak)

• The QXM series is known for long service life—nevertheless, regularly inspect shaft seals to prevent leakage

• If flow/torque output decreases, noise levels increase abnormally, or system temperature rises excessively, inspect and replace worn components promptly