• About Gear Pumps
  • Pumping Mechanism - Gear Pump vs. Centrifugal Pump
  • Metering with a Gear Pump
• Design Features
• Standard Materials of Construction
• Dimensions & Performance Curves

A gear pump is a "positive displacement" pump, unlike a centrifugal pump which is a "velocity" type pump. As the term suggests, a "velocity" type pump generates pressure and flow from the tangential and angular velocities (kinetic energy) imparted to the liquid by the speed and shape of the impeller. In a "velocity" type pump, pressure and flow can be modulated by throttling a discharge valve.

In a gear pump a volume of liquid is isolated in each tooth cavity. As the gears mesh, that cavity is reduced in volume. Since liquid is virtually incompressible, the reduced cavity generates pressure nearly independently of the gear speed and forces the liquid out the discharge port. Therefore, with a gear pump flow is relatively constant over varying pressures and throttling a discharge valve will not appreciably affect flow rate. To alter the flowrate with a gear pump, the RPM of the pump must change.

Since the means of generating pressure and flow in "positive displacement" pumps is by compressing a nearly incompressible liquid, extremely high pressures can be generated very rapidly in closed discharge piping. Therefore, it is highly recommended that a pressure relief valve be inserted in the discharge piping, upstream of the first potential blockage (closed valve, pipe obstruction).

Our gear pumps incorporate design features that will extend their accuracy, reliability, and maintainability over many years of use.

Housings are thick walled and are machined from bar stock, enabling them to withstand pressure better than thin injection molded units. Ordinary gear pumps use three or four housings to provide bearing support for the shafts, a cavity for the gearing, and suction and discharge porting. Our pumps use two housings for the same purpose. Potential misalignment is reduced.

Our drive shaft and drive gear are one integral unit, turned and precision ground from one piece of bar stock. The concentricity of the gear to the shaft is more precise than "keyed" or "pressed on" gears, resulting in smoother operation. The plastic idler gear is thermally secured to the metal idler shaft through a spline. This reduces stresses that normally arise from keyed plastic gears.

A quick change cartridge design allows rapid changeover for batch operations. Upon removing the piping from the cartridge, loosening two screws permits disengagement from the pump bracket with a quick camming motion. Reengagement of a new cartridge requires following the above steps in reverse. This feature works equally well when the pump is configured as a mag drive unit or as a lip sealed unit.