Gear Pumps

Gear Pumps

Gear Pumps are a type of rotary pump that moves the fluid by repeatedly enclosing a fixed volume using interlocking cogs or gears, transferring it mechanically using a cyclic pumping action. They are widely used for pumping high-viscosity fluids (oil, paints, foodstuffs), where a high-pressure output or precise amount of liquids is required.

Gear Pumps are separated into two main designs: internal and external.

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Gear pumps are an essential component in various industries and applications where the transfer of fluids is required. These pumps utilize the meshing of gears to create a smooth and continuous flow of liquid. They are known for their reliability, efficiency, and ability to handle a wide range of fluids, making them popular in industries such as automotive, manufacturing, and chemical processing. 

What Are Gear Pumps?

A gear pump is a type of positive displacement pump that uses interlocking gears to transfer fluids. It consists of two gears—a driving gear (the rotor) and a driven gear (the idler). These gears rotate in opposite directions, creating a seal that traps and moves the fluid from the inlet to the outlet. Gear pumps are known for their simplicity, durability, and efficiency in handling various types of fluids, from low to high viscosity.

How Do Gear Pumps Work?

Gear pumps operate through the meshing action of the interlocking gears. As the driving gear rotates, it transfers the fluid between the teeth of the gears and the pump housing. This trapped fluid is carried around the outer circumference of the gears, gradually building pressure and displacing the fluid towards the outlet. The rotation of the gears ensures a continuous flow, making gear pumps suitable for both low and high-flow rate applications.

Types of Gear Pumps

Gear pumps can be classified into two main types: external gear pumps and internal gear pumps.

Internal Gear Pumps

Internal gear pumps consist of an outer rotor and an inner rotor with fewer teeth. The outer rotor is the driving gear, while the inner rotor is the driven gear. As the gears rotate, fluid is trapped between the teeth and carried from the inlet to the outlet. The tight clearances between the gears and pump housing ensure minimal leakage. Internal gear pumps are known for their ability to handle high-viscosity fluids.

External Gear Pumps

External gear pumps are the most common type of gear pump. They consist of two identical gears, one being the driving gear and the other the driven gear. These gears rotate in opposite directions, creating a sealing action and transferring the fluid from the inlet to the outlet. The pump housing provides the necessary support and maintains the fluid flow path.

Advantages of Gear Pumps

Gear pumps offer several advantages over other types of pumps, making them a popular choice in many industries:

Compact Design: Gear pumps have a compact and space-saving design, making them suitable for installations with limited space.

Efficiency: Gear pumps provide high volumetric efficiency and can handle fluids with varying viscosities effectively.

Reliability: With few moving parts, gear pumps are reliable, durable, and require minimal maintenance.

Self-Priming: Gear pumps are capable of self-priming, allowing them to start pumping without the need for external priming.

Reversible Operation: Gear pumps can operate in both directions, providing versatility in applications where bidirectional flow is required.

Selecting a Gear Pump

When choosing a gear pump for your specific application, several factors should be taken into consideration:

Fluid Viscosity: The viscosity of the fluid being pumped is a crucial factor in selecting the appropriate gear pump type and size.

Flow Rate: Determine the required flow rate to ensure the gear pump can handle the desired volume efficiently.

Pressure Requirements: Consider the maximum pressure the pump needs to withstand to prevent damage and ensure reliable operation.

Material Compatibility: Ensure the pump materials are compatible with the fluid being pumped to avoid corrosion or degradation.

Temperature Range: Determine the operating temperature range to select a gear pump that can handle the required temperatures.

Maintenance of Gear Pumps

Proper maintenance and regular inspections are essential for ensuring the longevity and optimal performance of gear pumps. Here are some maintenance tips and common troubleshooting practices:

Regular Lubrication: Maintain proper lubrication to minimize friction and wear on the gears and bearings.

Cleanliness: Keep the pump and its surroundings clean to prevent contamination and ensure smooth operation.

Inspection: Regularly inspect the pump for any leaks, worn-out gears, or damaged seals and replace them promptly.

Temperature Control: Monitor the operating temperature to prevent overheating and thermal damage.

Noise and Vibration: Pay attention to any abnormal noise or excessive vibration, which could indicate a problem that needs addressing.


Gear pumps are versatile and reliable pumping devices that find applications in numerous industries. Their positive displacement mechanism, efficiency, and compact design make them an excellent choice for handling various fluids. Whether it's external gear pumps or internal gear pumps, each type offers unique advantages and can be tailored to specific requirements. With their reliability, efficiency, and versatility, gear pumps continue to be a reliable choice for fluid transfer needs.