Bucher QXM Internal Gear Pump & Motor

The Bucher QXM Series is a revolutionary “Internal Gear Unit” that functions equally well as a hydraulic pump or a hydraulic motor. Based on Bucher’s proven QX technology, the QXM is capable of 4-quadrant operation (driving and braking in both directions of rotation). It combines the robustness of gear pumps with the high pressure capabilities (up to 400 bar) typically reserved for piston units, all while maintaining exceptionally low noise levels. It is the ideal choice for heavy-duty fan drives, hydrostatic transmissions, and energy recovery systems.

Key Features:

Series: QXM (Sizes 22, 32, 42, 52, 62, 82)
Function: Bi-directional Pump & Motor
Max. Pressure: 400 bar (Continuous)
Speed: Up to 4000+ rpm
Design: Internal Gear, Non-compensated.

Product Overview The Bucher QXM utilizes a non-compensated internal gear design. Unlike external gear motors that rely on movable pressure plates (which can wear and leak), the QXM features 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. Its ability to switch seamlessly between pumping and motoring modes makes it perfect for Energy Recovery applications (e.g., lowering loads on forklifts or braking cycles on winches).

Why Choose Bucher QXM?

Whisper Quiet: The internal gear profile ensures significantly lower pulsation and noise compared to external gear or piston motors, often eliminating the need for expensive sound insulation.
High Pressure: Capable of continuous operation at 320-400 bar, allowing for compact, power-dense system designs.
Dual Functionality: Can be used to drive a load (Motor mode) and then recover energy by acting as a pump (Generator mode) in the same circuit.
Durability: The simple design with few moving parts and large plain bearings ensures a long service life, even with fire-resistant fluids (HFC).

Common Applications:

Fan Drives: Cooling systems in mobile machinery (low noise is critical).
Energy Recovery: Hybrid excavators, Forklift mast lowering.
Winches: Marine and forestry winches requiring smooth low-speed control.
Industrial: Sawmill drives, Crusher drives.

Specification	Value / Description
Product Type	Internal Gear Pump / Motor (Bi-directional)
Series	QXM (Mobil/Industrial)
Displacement Range ( $V_g$ )	QXM22: 5.0 – 8.0 cm³/rev QXM32: 10 – 16 cm³/rev QXM42: 20 – 32 cm³/rev QXM52: 40 – 63 cm³/rev QXM62: 80 – 125 cm³/rev QXM82: 160 – 250 cm³/rev
Continuous Pressure	400 bar (Sizes 22-62) / 320 bar (Size 82)
Max. Speed ( $n$ )	2500 – 4000 rpm (depending on size)
Viscosity Range	10 – 300 cSt (Standard)
Mounting	SAE 2-Bolt / 4-Bolt
Fluid Compatibility	Mineral Oil, HFC, HFD (Fire Resistant)
Common Part Numbers	Model Code: QXM[Size]-[Disp]-[Rot]-[Shaft] QXM32-010… (10cc Motor/Pump) QXM42-020… (20cc Motor/Pump) QXM52-050… (50cc Motor/Pump) QXM62-100… (100cc Motor/Pump) QXM82-200… (200cc Motor/Pump) (Note: QXM units often have a dedicated drain port for motor operation)