How Hydraulic Gear Pumps Work in Fluid Power Systems

Hydraulic gear pumps are pretty much essential in hydraulic systems. They’re valued for their efficiency, simplicity, and durability. To fully appreciate their utility, we need to understand how they operate, their design, and why they are among the most common types of hydraulic pumps in use today.

What Is a Hydraulic Gear Pump?

A hydraulic gear pump is a positive displacement pump designed to move hydraulic fluid from a reservoir to the actuators in a hydraulic system. Unlike centrifugal pumps, which rely on velocity to move fluid, gear pumps create a consistent flow by trapping fluid between gear teeth and pushing it through the system.

Their consistency makes gear pumps ideal for precise control and steady hydraulic power applications.

How Gear Pumps Work

A gear pump operates by using two gears to transfer hydraulic fluid. These gears rotate within a tightly sealed pump housing, creating a vacuum at the pump inlet to draw fluid in and force it through the pump outlet.

Key Components of a Gear Pump

• Driving Gear: The driving gear is powered by an external motor or engine, providing the mechanical force that drives the pump.
• Idler Gear: The idler gear meshes with the driving gear and rotates as it engages with the driving gear’s teeth.
• Pump Housing: The casing encloses the gears and maintains the hydraulic seal.
• Inlet and Outlet Ports: Fluid enters the pump through the inlet and is discharged through the outlet.

The Operating Process

1. Fluid Enters the Pump: As the gears rotate, the space between adjacent gear teeth increases on the inlet side, creating a vacuum that draws fluid into the pump.
2. Fluid Is Trapped: The fluid is carried around the outer edges of the pump housing as the gears continue to rotate. The tight clearances between the housing and the gears prevent leakage.
3. Fluid Is Forced Out: When the gears mesh together on the outlet side, the volume decreases, forcing the fluid out of the pump under pressure.

This simple yet effective process allows gear pumps to handle various flow rates and pressures, making them suitable for many hydraulic power applications.

Types of Gear Pumps

Gear pumps come in two primary designs:

 

• External Gear Pumps

 

External gear pumps consist of two identical gears, the driving gear and the idler gear, that rotate inside the pump housing. These pumps are commonly used in hydraulic systems because they:

• Handle higher pressures than internal gear pumps.
• They are well-suited for pumping clean hydraulic fluids.
• Offer excellent reliability and durability for demanding applications.

 

• Internal Gear Pumps

 

Internal gear pumps feature a smaller inner gear that rotates inside a larger outer gear. A crescent-shaped separator ensures that fluid flows from the pump inlet to the outlet. Internal gear pumps are typically used in applications requiring quieter operation and better performance with viscous fluids.

Advantages of Hydraulic Gear Pumps

Hydraulic gear pumps are widely used because they offer several key advantages:

1. Simplicity: Their simple design makes them easy to maintain and repair.
2. Efficiency: Gear pumps can maintain steady fluid flow even under high pressure.
3. Versatility: They are compatible with various hydraulic fluids and can handle varying flow rates.
4. Durability: The rugged construction of gear pumps ensures long service life, even in demanding conditions.

Applications of Hydraulic Gear Pumps

Gear pumps are used in various hydraulic systems, from mobile equipment like tractors and excavators to industrial applications such as hydraulic presses and manufacturing machinery. Their reliability and ability to handle higher pressures make them ideal for powering hydraulic cylinders, motors, and other actuators.

Common Issues with Gear Pumps

While hydraulic gear pumps are known for their durability, they can still experience issues if not properly maintained. Some common problems include:

1. Pump Failure Due to Contamination: Dirt, debris, or air bubbles in the hydraulic fluid can damage the gear teeth and compromise performance.
2. Leakage: Excessive wear on the pump housing or gears can cause internal leakage, reducing efficiency.
3. Overheating: Insufficient lubrication or excessive system pressures can lead to overheating, shortening the pump’s lifespan.

Regular maintenance, including clean fluids and proper filtration, can help mitigate these issues.

How Gear Pumps Compare to Other Hydraulic Pumps

Hydraulic systems utilise a variety of types of pumps, each with its strengths and weaknesses. Here’s how gear pumps stack up against other designs:

 

Gear Pumps vs Vane Pumps

• Gear pumps are more durable but less efficient than vane pumps at handling low-viscosity fluids.
• Vane pumps offer quieter operation, making them preferable for applications where noise is a concern.

Gear Pumps vs Piston Pumps

• Piston pumps, such as axial piston pumps and radial piston pumps, can handle much higher pressures and variable flow rates.
• Gear pumps are more affordable and easier to maintain, making them a cost-effective choice for less demanding applications.

Why Choose Gear Pumps for Your Hydraulic System?

Gear pumps are an excellent choice for many hydraulic systems due to their balance of performance, reliability, and cost. Their positive displacement design ensures consistent fluid flow, even under varying pressures, while their robust construction makes them ideal for heavy-duty applications.

At Hydrastore, we supply a wide range of hydraulic gear pumps, from external gear pumps for industrial applications to internal gear pumps suited for quieter, more precise operations. With decades of experience in fluid power and hydraulic systems, we can help you select the best pump for your needs.

Posted by admin in category Hydraulic Pumps Advice on Tuesday, 18th November 2025