QX41-040/31-025R Bucher Internal Gear Pump 40.6cc 160bar

Product Overview

The QX41-040/31-025R belongs to the Bucher Hydraulics QX series (covering QX21, QX41, QX82, QX23, QX33, QX43, QX53, QX63, QX83 and more), the 5th generation of proven internal gear pumps. Featuring an advanced tooth profile and hydrostatic/hydrodynamic bearing support for the ring gear, it delivers volumetric efficiencies up to 98%, extremely low pressure pulsation and noise levels. Manufactured to exact Bucher original specifications, it offers 100% drop-in interchangeability in mounting interfaces and performance for direct replacement without system modification. Every unit undergoes 100% simulated duty-cycle testing and is suitable for mineral oils, fire-resistant fluids and various special media in industrial and mobile hydraulic systems demanding low noise, high efficiency and long service life.

Technical Specifications 

• Full Model Code: QX41-040/31-025R
• Series: Bucher QX Internal Gear Pump
• Frame Size: QX41
• Effective Displacement: approx. 40.6 cm³/rev
• Continuous Working Pressure: 160 bar (pressure range 1, mineral oil)
• Intermittent/Peak Pressure: 210 bar
• Maximum Speed: approx. 2300–3000 rpm (depending on conditions and configuration)
• Minimum Speed: approx. 800 rpm
• Volumetric Efficiency: up to 98%
• Rotation: R – Right-hand (clockwise, viewed from shaft end)
• Control Type: Fixed-displacement internal gear
• Compatible Fluids: HLP mineral oils (DIN 51524), HFC fire-resistant fluids, etc.
• Approximate Weight: approx. 20 kg
• Mounting: Standard ISO/SAE flange

Key Technical Advantages

• Optimized tooth profile and large sealing areas achieve volumetric efficiencies up to 98%, significantly reducing internal leakage and energy consumption.
• Hydrostatic/hydrodynamic lubrication support of the internal ring gear enables operation with low-viscosity fluids, variable-speed drives and wide speed ranges for exceptional service life.
• Extremely low pressure pulsation and noise levels (typically <75 dB(A)) improve system comfort and reliability.
• Compact, robust construction with standardized interfaces provides true drop-in interchangeability, easy maintenance and compatibility with biodegradable and fire-resistant media.
• Full series subjected to rigorous simulated duty-cycle and certification testing (including ATEX options) ensures stable performance under high pressure and variable-speed conditions.

Application Areas

Injection molding machines, die-casting machines, hydraulic presses, machine tools, waste compactors, elevators/lifts, hydraulic power units, plastics processing equipment, forklifts and other industrial fixed and mobile hydraulic systems requiring low noise, high efficiency and long service life.

Expert Maintenance Tips

Use a flexible coupling during installation to ensure proper alignment and avoid additional radial/axial loads. Maintain fluid cleanliness at ISO 4406 20/18/15 or better (NAS class 9) and operate within the recommended viscosity range of 10–100 mm²/s (up to 300 mm²/s for start-up). Fully bleed the system and confirm adequate inlet pressure (minimum approx. 0.5–0.95 bar absolute) before initial operation. Periodically inspect shaft seals and port seals; avoid dry running. Observe minimum speed limits in variable-speed applications. During cold starts, build speed and pressure gradually to ensure proper lubrication. For special fluids or high viscosities, consult specific configuration options.