Gear Pumps Overview

Gear pumps have certain distinct properties, as independent specialists, we offer an extensive gear pump range including internal and external gear pumps from manufacturers such as Victor and Haight

To see more gear pumps click on the logos below:

Gear Pump - External:

Gear pump models of this type are well established and still the most widely manufactured version. As the two equally sized gears roll out of mesh, a partial vacuum is generated causing fluid to enter. Then as the elements rotate, the fluid becomes trapped and is carried around to the discharge side of the pump. Here the re-meshing elements displace the fluid thus producing a continuous pumping action. Although in principle each gear tooth generates a pulse, in practice the relatively high number of teeth, running speed etc makes the pumps flow pulse free. These inherent principles give this pump many useful characteristics:

• Self-priming action
• Pulse free fluid flow
• High pressures even at low flow rates
• Ability to pump high viscosity
• An output that is largely independent of viscosity and pressure
• An accurate output that is directly proportional to running speed
• An all metal construction that permits high temperatures and aggressive products
• The pump shafts are fully supported with the external gear pump design permitting a much greater pressure capability
• The gears are of true involute form and like simple transmission gears can run at high speeds without wear problems

Gear Pump - Internal:

Gear pump designs using external gears have been around almost since the beginnings of industry. However the internal gear, crescent pump or 'gear within a gear' design is less than a hundred years old. The design is still of positive displacement, where by a volume is swept by the meshing action of rotary gears, however using one gear within an other gives some distinct characteristics compared to the external gear design:

• Mechanically the pump has fewer bearing bushes in the product stream
• Gear teeth tend to be larger making the pump more 'open' and easier to 'fill' when pumping high viscosity fluids
• Shearing of the product is slightly less due to a reduced velocity differential between the two gears
• The gears are generally not of true involute form which restricts the rotational speed
• The shaft is overhung thus reducing pressure capability
• The construction lends itself to a modular pump design. Also maintenance is simpler as the pump can be of 'back pull out' build.
• The pump construction enables simple rotor end-clearance adjustment
• Generally this type of pump is more expensive to manufacture than the external gear design