QX23-008R Bucher Internal Gear Pump 7.9cc 320 Bar

Product Overview

The QX23-008R is a Bucher Hydraulics QX Series fixed-displacement internal gear pump, configured as a QX23 / Pressure Range 3 pump with an effective displacement of 7.9 cm³/rev.

Bucher describes the QX platform as its fifth-generation internal gear pump technology, developed for mobile and industrial hydraulics. The design uses a CAE-optimized gear profile, large sealing areas and a hydrodynamically/hydrostatically lubricated internal ring gear to achieve low pulsation, low noise, high efficiency and long service life. Bucher specifies volumetric efficiency of up to 98% for the QX family.

For the QX23-008R, the official Pressure Range 3 data specifies 320 bar maximum continuous pressure and 400 bar maximum intermittent pressure for mineral oil. The pump has a 3400 rpm maximum speed and 1100 rpm minimum speed. Its published reference flow is 11.5 L/min at 1450 rpm and 0 bar outlet pressure.

The R suffix identifies clockwise rotation when viewed from the shaft end. Bucher states that the standard QX pump is fixed displacement and driven in-line through a flexible coupling.

For replacement applications, the complete configuration must be matched. Shaft arrangement, frame size, pressure range, mounting flange, rotation, port configuration and seal selection all affect interchangeability. Bucher also provides a QX webshop specifically designed to identify replacement pump part numbers from an existing QX pump number.

Our replacement engineering focuses on in-place dimensional and functional interchangeability, followed by 100% simulated operating-condition testing before delivery.

Technical Specifications

• Model: QX23-008R
• Brand: Bucher Hydraulics
• Series: QX Internal Gear Pumps
• Pump Type: Fixed-displacement internal gear pump
• Frame Size: QX2
• Pressure Range: 3
• Effective Displacement: 7.9 cm³/rev
• Reference Speed: 1450 rpm
• Minimum Speed: 1100 rpm
• Maximum Speed: 3400 rpm
• Maximum Continuous Pressure: 320 bar with mineral oil
• Maximum Intermittent Pressure: 400 bar with mineral oil; maximum 20 seconds and not more than 10% of the duty cycle.
• Continuous Pressure with HFC: 280 bar
• Intermittent Pressure with HFC: 350 bar
• Reference Flow: 11.5 L/min at 1450 rpm and 0 bar
• Theoretical Flow at 3400 rpm: approximately 26.86 L/min; calculated from geometric displacement and not a published rated flow value.
• Theoretical Torque: 41 Nm at the specified maximum continuous-pressure condition.
• Theoretical Power Consumption: 6.2 kW at 1450 rpm under the specified mineral-oil condition.
• Control Method: Fixed displacement, mechanical
• Rotation: R = Clockwise
• Drive Method: In-line drive through a flexible coupling.
• Standard Mounting: ISO 3019/2 metric two-hole flange for QX2.
• Standard Seal: NBR; FPM/Viton available as an option.
• Hydraulic Fluid: HLP mineral oils according to DIN 51524 Part 2; HFC fluids are also supported.
• Operating Viscosity: 10–100 mm²/s
• Starting Viscosity: 10–300 mm²/s
• Mineral-Oil Temperature Range: −20°C to +80°C
• Long-Life Temperature Range: +30°C to +60°C, considering the permitted viscosity range.
• Maximum Fluid Contamination: ISO 4406 20/18/15
• Maximum Inlet Absolute Pressure: 1.5 bar
• Minimum Inlet Absolute Pressure: approximately 0.5–0.98 bar, depending on pump frame size and speed.
• Maximum Startup Pressure: 20 bar
• Volumetric Efficiency: up to 98% for the QX platform.
• Installation Orientation: unrestricted.
• Weight: Not separately published in the current official QX performance table for QX23-008R; no unsupported value is added.

Ordering Code Interpretation

QX23-008R

• QX — Bucher QX internal gear pump
• 2 — QX2 frame size
• 3 — Pressure Range 3
• 008 — 7.9 cm³/rev displacement class
• R — Right-hand / clockwise rotation.

This distinction is important because QX23 and QX24 represent different pressure ranges. They should not be treated as identical pumps with only a different displacement.

Key Technical Advantages

1. CAE-Optimized Gear Profile

Bucher states that the QX gear profile was conceived and optimized with CAE technology, producing a significant reduction in noise. Large sealing areas also contribute to higher efficiency.

2. Hydrodynamically/Hydrostatically Supported Ring Gear

The internal ring gear is supported by a hydrodynamic/hydrostatic lubrication film, enabling operation at low viscosities and across both low- and high-speed conditions.

3. 320 Bar Continuous Pressure

The QX23-008R provides 320 bar continuous pressure with mineral oil, combined with a 400 bar intermittent pressure capability subject to the stated duty-cycle restrictions.

4. Variable-Speed Drive Compatibility

Although the pump uses fixed displacement, Bucher explicitly states that QX pumps are suitable for variable-speed drives. Flow can therefore be varied by changing pump speed instead of using a fixed-speed pump with permanent throttling losses.

Bucher reports system-level results of up to 70% energy savings and up to 20 dB(A) noise reduction for suitable QX variable-speed-drive applications. These are application-level figures rather than guaranteed standalone pump performance.

5. Long Service Life

Bucher identifies extremely long service life as a major QX advantage and notes that manufacturing improvements have enabled lighter and more compact pumps without increasing demands on individual components.

6. Multi-Pump Configurations

QX pumps can be configured as double and triple pumps. The pumps operate hydraulically independently while sharing the drive shaft and, in double-pump arrangements, a common central suction connection.

Application Areas

The QX series is officially positioned for applications including:

• Hydraulic power units
• Plastic-processing machinery
• Die-casting machines
• Hydraulic presses
• Metal-forming machinery
• Machine tools
• Waste compactors
• Elevator and lifting systems
• Stackers
• Forklifts
• Variable-speed hydraulic drives
• Wind-power-related hydraulic systems.

Expert Maintenance Tips

1. Control the Inlet Pressure

Bucher specifies a maximum inlet absolute pressure of 1.5 bar and a minimum inlet absolute pressure of approximately 0.5–0.98 bar, depending on frame size and speed. Suction piping, filtration and reservoir conditions must be designed to maintain the required inlet conditions.

2. Protect the Pump at High Speed

The QX23-008R maximum speed is 3400 rpm. At high speed, inlet pressure, viscosity and suction-line pressure loss become increasingly important to pump filling and stability.

3. Do Not Treat 400 Bar as Continuous Pressure

For QX23-008R:

320 bar = continuous pressure

400 bar = intermittent pressure

The intermittent value is limited to 20 seconds and no more than 10% of the duty cycle.

4. Maintain Correct Viscosity

The published operating viscosity is 10–100 mm²/s, with starting viscosity up to approximately 300 mm²/s. Cold starts with high-viscosity oil should be controlled carefully before applying full speed and pressure.

5. Maintain Fluid Cleanliness

The QX technical data specifies a maximum fluid contamination level of ISO 4406 20/18/15. Monitor filter differential pressure and oil condition as part of preventive maintenance.

6. Use a Flexible Coupling

Bucher specifies in-line drive through a flexible coupling. Correct alignment is important to avoid transferring unnecessary radial or axial loads to the pump shaft.

7. Verify Each Stage of a Double Pump Separately

For configurations such as QX31-020/23-005R or QX32-012/21-016R, each pump stage has its own displacement, pressure and speed characteristics. The two stages operate hydraulically independently while sharing the drive arrangement.