Gear Pump | Types, Advantages, Disadvantages & Application|

June 23, 2024 By Usman Ahmed 8 minutes read

1. Introduction

A gear pump is vital in various industrial applications and is known for its efficiency and reliability in transferring fluids. As you know, a gear pump is a positive displacement pump that operates through the meshing of gears, which creates a continuous flow of liquid. Gear pumps are one of the most common types of pumps for hydraulic fluid power applications.

In this blog post, we will explore the fundamental principles of gear pumps, their types, and their advantages in different industries. So, let us first define what is a gear pump.

Gear pumps are a type of pump that moves fluids by using interlocking gears to pump the liquid through the system. These pumps generally consist of two gears that rotate against each other, creating a vacuum at the pump inlet to draw in the fluid. As the gear rotates, fluid moves out.

2. Brief History and Development

The concept of gear pumps dates back to the early 1600s. The first gear pump was created in the 16th century by a German engineer named Johannes Kepler.

Significant development in their design and application began in the late 19th century. Originally, these pumps were designed for transporting water, but as industries evolved, so did the applications of gear pumps. They became essential in transferring a variety of fluids in many industrial processes.

3. Operating Principle

Gear pumps move fluids using two gears that work together. Here’s how they work:

Interlocking Gears: The pump has two gears that mesh together. These gears are usually cylindrical and have teeth that interlock. A motor drives one of the gears, which in turn drives the second gear.
Fluid Inlet: As the gears rotate, they un mesh at the pump inlet, creating a low-pressure area. This low-pressure area draws the fluid into the pump.
Fluid Trapping: Once the fluid is inside, it gets trapped between the gear teeth and the pump casing. As the gears continue to rotate, they carry the fluid around the outside of the gears.
Fluid Movement: The fluid is then moved around the casing to the discharge side of the pump. The meshing of the gears at the discharge side pushes the fluid out of the pump.

4. Parts of a Gear Pump

4.1. Gears

Spur Gears: These gears have straight teeth and are parallel to the axis of rotation. They are the most common type used in gear pumps because they are simple and efficient.
Helical Gears: These gears have teeth cut at an angle to the face of the gear. They offer smoother and quieter operations than spur gears, but they are more complex and expensive to manufacture.

4.2. Casing

The casing of a gear pump is typically made from materials like cast iron, stainless steel, or aluminum, depending on the type of fluid being pumped and the operating conditions.

4.3. Bearings and Bushings

Bearings and bushings support the rotating shafts of the gears and reduce friction, which helps in the smooth operation of the pump.

4.4. Seals and Gaskets

Seals and gaskets are used to prevent fluid leaks from the pump. They ensure that the fluid stays within the designated pathways inside the pump.

4.5. Shafts

The shafts connect the gears to the motor and transmit the rotational power needed to drive the gears.

4.6. End Plates

End plates are used to keep all the components of the pump aligned and in place. They help maintain the correct positioning of the gears and other internal parts.

5. Types of Gear Pumps

There are two main types of gear pumps.

There are generally two main types of gear pumps used in industry.

External Gear Pump
Internal Gear Pump

5.1. External Gear Pumps

External gear pumps are also divided into types.

Spur Gear Pumps
Helical Gear Pumps

1. Spur Gear Pumps

Spur gear pumps are the most common type of external gear pumps. They use two identical gears with straight teeth that rotate in opposite directions.

The fluid is trapped between the teeth and the casing and moved from the inlet to the outlet. These pumps are known for their simplicity and efficiency, making them ideal for various applications.

2. Helical Gear Pumps

Helical gear pumps use gears with angled teeth. Compared to spur gears, the angled teeth provide smoother and quieter operation.

The fluid movement is similar, trapped between the gear teeth and the casing, but the helical design reduces pulsation and noise. These pumps are often used in applications where noise reduction is essential.

5.2. Internal Gear Pumps

Internal gear pumps are also divided into types.

Cresent Gear Pumps
Gerotor Gear Pumps

1. Crescent Gear Pumps

Crescent gear pumps have an internal and external gear separated by a crescent-shaped partition. The internal gear rotates inside the outer gear, and the crescent helps to create a seal between the inlet and outlet.

Fluid is trapped in the spaces between the gears and the crescent and then moved from the inlet to the outlet. These pumps are known for their ability to handle viscous fluids and their smooth, quiet operation.

2. Gerotor Pumps

Gerotor pumps consist of an inner and outer rotor with different numbers of teeth. The inner rotor has one less tooth than the outer rotor and is mounted off-center.

As the inner rotor turns, the outer rotor rotates, creating a series of expanding and contracting cavities that move the fluid from the inlet to the outlet.

Gerotor pumps are compact and efficient, making them suitable for a variety of applications, especially where space is limited.

6. Advantages of Gear Pumps

Advantages

1. High Efficiency: Gear pumps can move a large amount of fluid with minimal energy loss.

2. Self-Priming Capability: Gear pumps can start pumping without needing to be filled with fluid first.

3. Consistent Flow Rate: Gear pumps provide a steady and reliable fluid delivery.

4. Ability to Handle High-Viscosity Fluids: Gear pumps can easily move thick, dense fluids.

5. Compact Design: Gear pumps are ideal for use in limited spaces due to their small size.

6. Low Maintenance Requirements: Gear pumps require minimal maintenance because of their sturdy construction.

7. Reversible Flow Direction: Gear pumps can pump fluid in either direction.

7. Disadvantages of Gear Pumps

Disadvantage’s

1. Limited Ability to Handle Abrasive Fluids : Gear pumps can wear out quickly when used with abrasive fluids.

2. Potential for Cavitation: Gear pumps can experience cavitation if not properly managed.

3. Noise and Vibration Issues: Gear pumps can produce significant noise and vibration during operation.

4. Limited Pressure Capabilities: Gear pumps may not achieve as high pressures as other pump types.

5. Temperature Sensitivity: Gear pumps can be sensitive to temperature changes, affecting performance

8. Applications of Gear Pumps

Applications

1. Automotive Industry: Gear pumps are used in automotive engines for lubrication and fuel injection.

2. Chemical Processing: Gear pumps are utilized for handling and transferring chemicals and solvents.

3. Oil and Gas Industry: Gear pumps are essential for transporting crude oil, lubricants, and refined products.

4. Food and Beverage Industry: Gear pumps are used for moving syrups, oils, and other food-grade liquids.

5. Pharmaceuticals: Gear pumps are employed to produce and transfer medicinal liquids and ingredients.

6. Hydraulic Systems: Gear pumps are key components in hydraulic systems for machinery and equipment.

9. Practical calculations

9.1. Flow rate of the gear pump

The flow rate of a gear pump can be calculated using the formula:

Where:

= Flow rate (cubic meters per second, $s$ )
= Pump speed (revolutions per second, $s$ )
= Displacement per revolution (cubic meters per revolution, $re v$ )
= Volumetric efficiency

9.2. Pressure of the gear pump

The pressure can be calculated using the formula:

Where:

= Pressure (Pascals, Pa)
= Torque (Newton-meters, Nm)
= Displacement per revolution (cubic meters per revolution, $re v$ )
= Mechanical efficiency ( dimensionless )

9.3. Velocity of the gear pump

The velocity V of the fluid can be calculated using the formula:

$\ A$

Where:

= Velocity (meters per second, $m / s$ )
= Flow rate (cubic meters per second, $/ s$ )
= Cross-sectional area of the pipe (square meters, )

9.4. NPSH Requirements for Gear Pumps

Net Positive Suction Head (NPSH) is essential to prevent cavitation. The pump manufacturer specifies the NPSH required (NPSHr), which must be less than the NPSH available (NPSHa) in the system to ensure proper operation.

9.5. Power Consumption

The power consumed by a gear pump can be calculated using the formula:

Where:

= Power (Watts, W)
= Flow rate (cubic meters per second, $s$ )
= Pressure difference (Pascals, Pa)
Overall efficiency (dimensionless, typically a percentage expressed as a decimal)

10. Comparison with Other Pump Types

11. Maintenance and Troubleshooting

Proper maintenance and troubleshooting are essential to ensure their optimal performance and longevity in gear pumps.

1. Noise and Vibration:

Causes: Air entrainment, cavitation, misalignment, worn gears or bearings.
Solutions: Check for leaks in the suction line, ensure the pump is aligned correctly, inspect and replace worn components, and ensure proper fluid levels.

2. Low Flow or No Flow:

Causes: Clogged suction line, worn gears, improper pump rotation, relief valve set too low.
Solutions: Clean the suction line, inspect and replace worn gears, verify correct rotation, and adjust the relief valve setting.

3. Overheating:

Causes: Excessive fluid viscosity, high operating speed, blocked cooling system.
Solutions: Use the correct fluid, reduce the pump speed, and clean the cooling system.

4. Leaking:

Causes: Worn seals, damaged housing, excessive pressure.
Solutions: Replace seals, inspect and repair or replace the housing, and reduce system pressure.

5. Excessive Wear:

Causes: Contaminated fluid, improper lubrication, excessive speed or pressure.
Solutions: Filter the fluid, ensure proper lubrication, and adjust speed and pressure to recommended levels.

12. Advancements and Future Trends

1. Advanced Materials:

Composite Materials: Use of high-performance composites to reduce weight while maintaining strength and durability.
Ceramics: Incorporation of ceramic materials for improved wear resistance and longevity, especially in abrasive environments.
Advanced Alloys: Development of new alloys that offer enhanced corrosion resistance and strength and are suitable for harsh chemical processing applications.

2. Coatings:

Diamond-Like Carbon (DLC) Coatings: These provide exceptional hardness and low friction, enhancing gear pumps’ wear resistance and efficiency.
PTFE and Other Non-Stick Coatings: Used to minimize friction and reduce the potential for build-up of processed materials on gear surfaces.
Corrosion-Resistant Coatings: Specialized coatings are applied to protect against chemical corrosion, extending the service life of pumps in corrosive environments.

14. Case Studies on Gear Pumps

1. Chemical Processing Industry:

Company: A leading chemical manufacturer
Implementation: Installation of high-performance gear pumps with corrosion-resistant coatings for handling aggressive chemicals.
Outcome: Improved reliability and reduced maintenance costs due to enhanced resistance to chemical corrosion and wear. The pumps achieved a 20% increase in service life, reducing downtime and increasing production efficiency.

2. Food and Beverage Industry:

Company: A significant beverage production plant
Implementation: Use of gear pumps with FDA-approved materials and sanitary design for pumping viscous syrups and sauces.
Outcome: Enhanced hygiene and compliance with food safety standards. The gear pumps provided consistent flow rates and precise dosing, improving product quality and reducing waste by 15%.

3. Automotive Industry:

Company: A global automotive parts manufacturer
Implementation: Integration of IoT-enabled gear pumps in the cooling systems of high-performance engines.
Outcome: Real-time monitoring and predictive maintenance capabilities reduced unexpected failures by 25%. Improved thermal management enhanced engine performance and longevity.

15. Problem-Solving Examples

1. Issue: Cavitation in Hydraulic Systems

Scenario: A construction equipment manufacturer experienced frequent cavitation issues in its hydraulic systems, which damaged the pumps and caused operational inefficiencies.
Solution: Installation of gear pumps with optimized inlet designs and anti-cavitation features.
Result: The occurrence of cavitation was reduced by 80%, significantly extending the lifespan of the pumps and improving the reliability of the hydraulic systems.

2. Issue: High Wear and Tear in Mining Operations

Scenario: A mining company experienced rapid wear and tear of gear pumps due to the abrasive nature of the slurry being pumped.
Solution: Implementation of gear pumps with ceramic coatings and reinforced gears designed for high abrasion resistance.
Result: The pumps’ durability increased, with a 50% reduction in maintenance frequency and costs. This led to uninterrupted operations and higher productivity in the mining process.

Conclusion

Gear pumps are integral to many industries due to their simplicity, reliability, and efficiency. External gear pumps, known for high pressure and flow rate capabilities, are ideal for industrial applications.

With their smooth and quiet operation, internal gear pumps handle various fluids, making them perfect for precise flow control tasks.

Despite their advantages, such as easy maintenance and versatility, gear pumps face challenges like wear and limited suction lift.

They are widely used to handle viscous fluids in automotive oil pumps, industrial chemical processing, and food and beverage applications.

Understanding these aspects ensures informed decisions, optimizing efficiency and reliability across various applications.

FAQ

What is a gear pump?

A gear pump is a positive displacement pump that uses interlocking gears to move fluids. It operates through the meshing of gears, creating a continuous flow of liquid.

What are the main types of gear pumps?

There are two main types of gear pumps: external gear pumps and internal gear pumps. External gear pumps include spur and helical gear pumps, while internal gear pumps include crescent and gerotor gear pumps.

How does an external gear pump work?

External gear pumps use two identical gears with straight or angled teeth that rotate in opposite directions. The fluid is trapped between the teeth and the casing and moved from the inlet to the outlet.

How does an internal gear pump work?

Internal gear pumps have an internal and external gear separated by a partition. The internal gear rotates inside the outer gear, trapping fluid in the spaces between the gears and the partition, moving it from the inlet to the outlet.

What is classification of gear pumps?

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

External Gear Pumps: These pumps consist of two external gears that mesh outside the pump casing. Fluid is carried between the gear teeth and the casing to the discharge port.
Internal Gear Pumps: Internal gear pumps have an internal and external gear set configuration. Fluid enters the pump inlet and is carried between the teeth of the internal gear and the crescent-shaped internal housing to the discharge port.

What are the advantages of gear pumps?

Gear pumps are favored for their simple design, reliability, and ability to handle a wide range of fluids efficiently. They offer compact size, cost-effectiveness, and smooth, pulsation-free flow, making them ideal for various industrial applications.

What are the disadvantages of gear pumps?

Disadvantages of gear pumps include limited efficiency at high pressures, the potential for fluid leakage due to clearance gaps, and sensitivity to viscosity changes, which can affect performance.

In which industries are gear pumps commonly used?

Gear pumps are commonly used in hydraulic systems for machinery and vehicles, chemical processing for handling viscous fluids, and food processing for gentle product handline.

What materials are gear pump casings made from?

Gear pump casings are typically made from materials such as cast iron, stainless steel, aluminum, or various types of engineered plastics (like polyamide or PTFE).

What is the principle of gear pump?

The principle of a gear pump involves using the meshing of gears to create a fluid flow. As gears rotate, they create suction at the inlet, trapping fluid between the gear teeth and casing.

This trapped fluid is carried around the gears to the outlet, where it is discharged due to the continuous meshing and unmeshing of the gear teeth.

How do gear pumps work?

Gear pumps use gears’ meshing to create a pumping action. As gears rotate, they draw in fluid at the inlet side, trap it between the gear teeth and the pump casing, and then push it out through the discharge side as the gears continue to rotate, creating a continuous flow of fluid.

What is the maximum pressure for a gear pump?

he maximum pressure for a gear pump typically ranges from 250 psi (pounds per square inch) to 500 psi, depending on the design, size, and materials used in construction.

What causes noise and vibration in gear pumps, and how can it be addressed?

oise and vibration in gear pumps can be caused by:

Misalignment of gears
Worn gears
Cavitation due to insufficient fluid supply or suction line restrictions
Excessive load beyond recommended capacity

Gear Pump | Types, Advantages, Disadvantages & Application|