Internal gear pumps are widely used in many industries: food manufacturers use them to deliver thick pastes and seasonings; petrochemical industries deploy them in high-pressure metering applications and engine manufacturers use them for oil transportation. They are used as delivery pumps. Specially designed for aerospace applications. The hydraulic pump will meet SAE bolt hole requirements.

In the early 1990s, automotive engine manufacturers switched from external gear oil pumps to internal gear designs, including cycloids and two-tooth differentials. The crescent type is particularly suitable for conveying large quantities of products at low rpm. With the disappearance of the distributor-based ignition system and associated camshaft gearing, some of these pumps were driven directly from the camshaft.

Internal Gear Pumps can pump fluids of almost any viscosity, but for thicker materials, speed must usually be reduced. They are not suitable for materials containing solids because they cause premature wear. Internal gear pumps are self-priming and can be used in low NPSH applications. They usually provide smooth, continuous flow. In theory, at least they are bidirectional. They can be provided individually or in combination in the form of a tandem design.


Internal gear pumps can be manufactured for hygienic design in food, beverage and pharmaceutical services. The rotor can be suspended, supported by a single bearing or a pair of bearings outside the housing, and offers a variety of seals. These internal pump components are accessible through the cover plate for direct disinfection. Available in tightly coupled and hermetically sealed designs.

Gerotor's geometry can be designed either on stock or on customer request. The viscosity of the fluid to be pumped will affect the backlash of any given cycloid or pair of trochoids. Although it is usually an internal component that drives the outer ring, a special design can be used where the outer ring is driven. Generally, the fewer lobes, the higher the speed. The more lobes, the smoother the flow. Although a three-lobed rotor can theoretically be used, it is not practical for several reasons, so the four-lobed rotor is set as the minimum starting point.

Compared to external gear pumps, internal gear pumps generally have higher initial costs but lower wear rates, resulting in longer service life. Although advanced cycloidal gear manufacturing methods make these pumps extremely adaptable and cost-effective, the designs are more complex. One disadvantage of internal gear pumps is the overhanging load imposed on their bearings. However, this makes disinfection simple.

A common disadvantage that all gear pumps share with other positive displacement pumps, such as vane pumps, is that they cannot provide a variable flow rate at a given input speed. When this is required, a workaround is to use a drive with speed control, although this is not always a viable solution.

Finally, although rotary positive displacement pumps are capable of pumping water, their main application is in oils and viscous liquids, because friction surfaces need to be kept lubricated and it is difficult to seal very thin fluids. For most water-based applications, centrifugal or dynamic displacement pumps are the clearer choice.



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