Gear Pump
Table of Contents
What Is a Gear Pump?
A gear pump is a type of positive displacement pump designed to move fluid by trapping it between the teeth of rotating gears and the pump casing. As the gears turn, fluid is pushed from the inlet side to the outlet, delivering a steady, pulseless flow—ideal for applications requiring precision and reliability.
Unlike centrifugal pumps, which rely on high-speed impellers, gear pumps deliver consistent volume regardless of pressure, making them well-suited for high-viscosity fluids and systems that demand tight flow control.
Gear pumps are commonly used in industries like oil & gas, chemical processing, manufacturing, lubrication systems, and fluid handling solutions where durable, compact pumps are needed to move oils, fuels, additives, and other challenging fluids efficiently.
Whether you’re dosing chemicals in a refinery or transferring gear oil in a hydraulic system, gear pumps offer rugged performance in demanding conditions.
How Does a Gear Pump Work?
At its core, a gear pump works by using the meshing action of gears to move fluid. As the gears rotate, they create suction at the inlet, pulling fluid into the pump. The fluid becomes trapped in the spaces between the gear teeth and the casing, then carried around the outside of the gears to the outlet, where it is discharged under pressure.
There are two main types of gear pumps: external and internal.
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External gear pumps use two identical gears—one driven by a motor and the other idling—to displace fluid with high precision. They’re ideal for gear oil pump applications, chemical transfer, and lubrication systems.
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Internal gear pumps feature one gear inside another, with a crescent-shaped spacer between them. These pumps provide smoother flow and are commonly used in hydraulic gear pump systems where fluid consistency and low pulsation are critical.
Whether you’re wondering how does a gear pump work or trying to determine the right pump for a hydraulic or gear oil application, understanding these mechanisms is key to choosing the most efficient solution for your fluid handling system.
Types of Gear Pumps
Gear pumps come in several configurations, each suited to specific applications based on flow, pressure, and fluid type. Understanding the different types will help you determine the best fit for your fluid handling needs.
External Gear Pumps
These pumps use two identical, interlocking gears—one driven, one idler—rotating in opposite directions. As the gears turn, fluid is drawn in and carried around the casing before being discharged under pressure.
Best For: Chemical transfer, lubrication systems, fuel oil, and light viscosity fluids.
Internal Gear Pumps
An internal gear pump has one gear inside another, with a crescent-shaped spacer between them. This design provides smooth, low-pulsation flow and better suction capabilities.
Best For: Viscous fluids, food-grade materials, polymers, and resins.
Hydraulic Gear Pumps
Used in hydraulic systems, these pumps are built to handle high pressures and transfer energy through hydraulic fluid.
Best For: Industrial machinery, mobile equipment, and hydraulic lift systems.
While gear pumps are ideal for precision and high-pressure systems, other pump types may be better for specific scenarios. See below.
Gear Pumps vs Other Pump Types
When selecting the right fluid handling solution, it’s important to understand how gear pumps compare to other common pump types. Below is a breakdown of the strengths, limitations, and ideal use cases of gear pumps versus other technologies:
Gear Pump vs. Centrifugal Pump
Gear Pumps provide a steady, non-pulsing flow and are ideal for high-pressure applications and viscous fluids. As positive displacement pumps, they maintain consistent flow regardless of pressure changes. Centrifugal Pumps excel in high-flow, low-viscosity applications and are widely used for water and general-purpose fluid transfer. Their performance varies with system pressure and is best suited for continuous flow needs.
✅ Choose gear pumps when precision, pressure, and handling viscous fluids are key.
✅ Choose centrifugal pumps for high-volume, low-viscosity fluid transfer in clean fluid systems.
Gear Pump vs. Diaphragm Pump
Gear Pumps are perfect for clean, lubricating fluids and offer consistent flow in systems where pressure and reliability matter. Diaphragm Pumps shine in handling abrasive slurries, corrosive fluids, and solids without damage. Their seal-less design allows for dry-run capability and minimal leak risk.
✅ Choose gear pumps for lubrication, hydraulic oils, and pressure-sensitive applications.
✅ Choose diaphragm pumps for solids-laden, corrosive, or hazardous fluids where leak prevention is critical.
Gear Pump vs. Peristaltic Pump
Gear Pumps are more compact and efficient in general fluid transfer systems, particularly in industrial and chemical processing. Peristaltic Pumps provide contamination-free pumping, ideal for sensitive fluids as the liquid only contacts the tubing.
✅ Choose gear pumps when efficiency and compact design for clean fluids are required.
✅ Choose peristaltic pumps for sterile, shear-sensitive, or food/pharma-grade fluid transfer.
Gear Pump vs. Charge Pump
Gear Pumps act as primary fluid movers, offering stable and pressurized flow in a variety of systems. Charge Pumps serve as support pumps in hydraulic systems, maintaining low-pressure supply to ensure cavitation-free operation of the main pump.
✅ Choose gear pumps for mainline fluid transfer with high pressure and consistency.
✅ Choose charge pumps to maintain pressure and supply in hydraulic circuits.
Applications of Gear Pumps
Gear pumps are among the most versatile and durable pump types in fluid handling equipment, making them ideal for a wide range of industrial, municipal, and commercial uses. Their ability to handle
Gear pumps are highly valued across a range of industries due to their consistent flow, compact design, and ability to handle viscous or lubricating fluids. Their versatility makes them a core component in many types of fluid processing equipment and fluid handling systems.
Industrial Lubrication Systems
Gear pumps are widely used in lubrication circuits for manufacturing equipment, turbines, and gearboxes. Their ability to maintain consistent flow at high pressures makes them ideal for gear oil pump applications in continuous-duty environments.
Fuel Transfer and Injection
In fuel systems, gear pumps enable reliable transfer of diesel, gasoline, and fuel oil. Their precise, pulseless delivery is critical for fuel injection in engines and burners, ensuring efficiency and performance across pump and equipment setups.
Chemical and Fluid Processing Equipment
Gear pumps are frequently integrated into fluid processing equipment where chemical compatibility, metered flow, and corrosion resistance are essential. They’re commonly used for adhesives, resins, polymers, and other industrial chemicals, including pipeline chemical injection and nitrogen services like those offered by N2 Solutions.
Hydraulic Systems
As a type of hydraulic gear pump, gear pumps provide the primary means of fluid movement in industrial and mobile hydraulic systems. They convert mechanical energy into hydraulic energy, powering everything from construction machinery to automation systems. Gear pumps are critical in hydraulic systems for oilfield equipment, including mobile rigs and high-pressure components. Their ability to convert mechanical energy into hydraulic pressure makes them ideal for applications supported by torque tools, drill rig tools, or high-tolerance blowout preventers and valves.
Gear Pumps in Fluid Handling Systems
Gear pumps are a foundational element in fluid handling systems, not only for their primary pumping capabilities but also for how they integrate with and support other technologies in the field. Their compact design, steady flow, and ability to handle viscous fluids make them valuable across many demanding operations.
Integration with Horizontal Directional Drilling (HDD) Systems
In horizontal directional drilling (HDD), gear pumps are used to circulate drilling lubricants, manage fluid delivery, and support mud system components. Their high-pressure, low-pulsation output makes them ideal for steady chemical injection and fluid transfer in trenchless applications.
Use in Well Pump Replacement
During well pump replacement or servicing, gear pumps are often used for flushing, circulating lubricants, or transferring chemicals required for system prep or cleanup. Their ability to self-prime and manage viscous fluids makes them a reliable tool during transitional or maintenance phases.
Supporting Other Pump Types
Gear pumps play a key supporting role alongside other specialized pumps:
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Trash pumps handle large debris, while gear pumps are used to inject additives or manage finer fluid control.
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Grinder pumps break down solids in wastewater systems, with gear pumps providing chemical dosing or lubricant support.
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Hydra-Trech pumps rely on auxiliary systems for precise fluid delivery, where gear pumps ensure steady, controlled input to sensitive equipment.
Together, these components create cohesive, efficient fluid handling equipment setups that perform under pressure and across variable conditions.
Choosing the Right Gear Pump
Selecting the right gear pump is critical to optimizing system performance, minimizing wear, and ensuring long-term reliability in your fluid handling solutions. A variety of factors should guide your decision, from material compatibility to mounting configurations.
Material Compatibility
Gear pumps are available in multiple material options—cast iron, carbon steel, and stainless steel—each suited to different fluid types.
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Use stainless steel for corrosive chemicals or food-grade applications.
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Choose cast iron for general-purpose fluids like oil or water-based lubricants.
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Opt for carbon steel when strength and pressure resistance are top priorities.
Pressure & Flow Rate Requirements
Each gear pump has an operating window for pressure and flow rate. High-pressure systems (like hydraulic gear pumps) require heavy-duty construction, while low-flow applications benefit from smaller, more efficient pumps. Be sure to match the pump’s performance specs to your system’s total dynamic head and desired throughput.
Viscosity & Fluid Type
Gear pumps excel in handling viscous and non-lubricating fluids, including oils, resins, and heavy chemicals. Consider the fluid’s characteristics—such as temperature, abrasiveness, and particulate load—to ensure the selected pump won’t experience premature wear or cavitation.
Port Orientation & Mounting Considerations
Port orientation (top, side, or bottom inlet/outlet) affects how the pump integrates into your fluids handling system. Pay attention to:
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Mounting space and configuration
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Inlet height and orientation for gravity-fed systems
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Ease of maintenance and accessibility
Choosing the right gear pump isn’t just about specs—it’s about matching the equipment to your operating environment, ensuring long-term efficiency and reliability.
Maintenance, Troubleshooting & Longevity
Gear pumps are known for their durability, but like any piece of fluid handling equipment, proactive care can extend their lifespan and performance.
Common Issues with Gear Pumps
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Excessive noise or vibration – May indicate cavitation or misalignment.
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Drop in flow rate or pressure – Often due to internal wear or clogged suction lines.
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Seal leaks – Caused by worn seals or incompatible fluids.
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Overheating – Typically a result of running at too high a speed for the fluid’s viscosity.
Tips for Routine Maintenance
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Perform regular visual inspections for leaks and unusual wear.
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Check and replace seals and bearings based on service intervals.
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Monitor fluid temperature and viscosity to prevent overheating.
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Keep pump internals clean and free of solid contaminants.
When to Repair vs. Replace
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Repair when wear is isolated to replaceable parts like gears, seals, or bearings.
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Replace when housing damage, corrosion, or long-term degradation reduces efficiency.
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EV Pump offers custom repair & rebuild services as well as new pump solutions tailored to your operation.
Compatible Systems
Gear pumps work seamlessly with Webtrol Pumps, custom EV Pump systems, and other integrated fluid processing equipment in commercial, industrial, and drilling applications.
Gear Pump FAQs
What’s the difference between internal and external gear pumps?
Internal gear pumps use two gears—one inside the other—for smoother flow and better suction. External gear pumps use two meshing gears and are typically higher pressure but noisier.
How long do gear pumps last?
With proper maintenance, gear pumps can last 5–15 years, depending on usage, fluid type, and system conditions.
Can gear pumps handle solids or slurries?
Gear pumps are not ideal for solids or abrasive slurries. They perform best with clean, viscous fluids. For solids-laden applications, consider diaphragm pumps or trash pumps.
Are gear pumps self-priming?
Yes, most gear pumps are self-priming, making them suitable for on-demand or intermittent-use systems like fuel transfer, lubrication circuits, or chemical dosing.
Do you have questions about gear pumps or other fluid handling needs? No problem. Get in touch with Clark or ask him about a free site audit!