QX31-025R Bucher Internal Gear Pump High Pressure QX Series

Product Overview

The QX31-025R (and related models in the QX61, QX33, QX43, QX53, QX63, QX83 series) is a high-pressure internal gear pump from the Bucher Hydraulics QX 5th-generation range. Featuring gap compensation, it achieves volumetric efficiency up to 98%, with extremely low pressure pulsation, low noise and long service life. Displacements range widely (approx. 5–500 cm³/rev) with maximum working pressures up to 400 bar (depending on pressure range). Suitable for fixed or variable-speed drives and available in single or multiple configurations, the pump offers direct bolt-on interchangeability with OEM units and undergoes 100% simulated duty testing for industrial and mobile open-circuit hydraulic systems.

Technical Specifications 

• Model: QX31-025R (QX series frame sizes QX2 / QX3 / QX4 / QX5 / QX6 / QX8)
• Pump type: High-pressure internal gear pump (gap-compensated)
• Displacement (QX31-025): Approx. 25.2 cm³/rev
• Continuous operating pressure (pressure range 1 example): Approx. 125–160 bar (mineral oil)
• Intermittent pressure: Approx. 160–210 bar
• Peak pressure: Up to 400 bar (higher pressure range variants)
• Maximum speed: Approx. 3000 rpm (QX3 frame)
• Volumetric efficiency: Up to 98%
• Rotation: R = Clockwise (viewed from shaft end, standard)
• Compatible fluids: HLP mineral oils, HFC, low-viscosity and biodegradable fluids
• Other: Low pulsation, low noise (typically <75 dB(A)); ATEX and other certifications available; multiple-pump configurations possible

Key Technical Advantages

1. True drop-in interchangeability: Manufactured to OEM dimensional and porting standards for bolt-on replacement without modifications.
2. Ultra-high volumetric efficiency and low pulsation: Special gear profile and gap compensation deliver up to 98% efficiency with minimal pressure pulsation.
3. Low noise and long service life: Quiet operation and simple, robust construction ensure extended durability.
4. Wide pressure and fluid compatibility: Selectable pressure ranges up to 400 bar; compatible with various hydraulic oils and low-viscosity fluids.
5. 100% simulated duty testing: Full pressure, flow, noise and endurance verification before shipment ensures ready-to-install reliability.

Application Areas

• Injection molding machines, presses and die-casting equipment
• Machine tools and industrial hydraulic power units
• Elevators, waste compactors and material handling
• Cranes and heavy-duty mobile equipment
• Open-circuit systems requiring low-noise high-pressure internal gear pumps

Expert Maintenance Tips

• Confirm clockwise rotation (R) and flange/port compatibility before installation; use recommended hydraulic fluid and maintain cleanliness (ISO 20/18/15 or better).
• Start at low speed unloaded; check for leaks and noise. Ensure minimum inlet pressure requirements (approx. 0.5–1.5 bar absolute) are met.
• Regularly inspect seals and bearings; keep suction lines unrestricted to prevent cavitation.
• Keep oil temperature and viscosity within recommended ranges (typically 10–100 mm²/s); avoid over-pressure operation.
• For multiple-pump or special pressure-range configurations, verify the complete order code and consult technical support.