Allweiler Rotating Equipment

Internal Gear Pumps

Our internal gear pumps are volumetric displacement units available in five sizes, each covering a range of displacement options to suit varying application demands. Both radial and axial clearance compensation — proportional to operating pressure — deliver consistently high volumetric efficiency across the full operating range, while keeping noise levels low.

Optimised load distribution combined with precision friction bearings allows for continuous duty at high pressures, resulting in extended service life. Units are also available in multiple versions that can be combined into multi-flow groups for applications requiring independent hydraulic circuits.

Category:
Parameter Size 3 Size 4 Size 5 Size 6 Size 7
Displacement range (cm³/rev) 3.6 – 10.2 13.3 – 32.6 33.1 – 64.9 64.1 – 126.2 125.8 – 251.7
Flow rate at 1500 rpm (l/min) 5.4 – 15.3 19.9 – 48.9 49.6 – 97.3 96.1 – 189.3 188.7 – 377.5
Ambient temperature (°C) -20 to +60
Fluid temperature (°C) -20 to +80
Recommended viscosity (cSt) 25 – 100
Mass — single pump (kg) 4.0 – 4.8 8.6 – 11.0 15.5 – 18.7 29.2 – 35.0 46.5 – 59.0

 

Configuration Options

  • Rotation direction: clockwise or counterclockwise
  • Shaft end type: cylindrical keyed (standard); other shaft ends available upon request
  • Hydraulic connections: SAE J518 flanged fittings
  • Mounting flange: SAE J744 / ISO 3019-1
  • Available with through-drive shaft for multi-pump configurations
  • Seal material: NBR for mineral oil service; Viton front shaft seal on sizes 3–6

Fluid Requirements

Mineral oil based hydraulic fluids with anti-foam and antioxidant additives are recommended. Water glycol solutions (HFC, water content ≤ 40%) are permitted with reduced performance ratings of at least 20% and a maximum fluid temperature of 50°C. Phosphate ester fluids (HFD) are not permitted.

Installation Notes

The pump can be installed in any orientation. Suction line fluid velocity must not exceed 1 m/s (1.5 m/s with positive inlet pressure), with the suction line inlet positioned at least 50 mm below minimum oil level. The pump is self-priming across the full specified speed range. Air must be vented from the delivery line on first start-up. Use a flexible coupling for motor-pump connection, consult our technical team for installations involving axial or radial shaft loads.

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