Classification Standards of Hydraulic Gear Pumps: A Detailed Overview

Hydraulic gear pumps are favored for their straightforward design, ease of maintenance, and ability to provide steady flow. They are commonly found in industrial machinery, construction equipment, agricultural tools, and mobile hydraulics.

Key Classification Standards of Hydraulic Gear Pumps

Hydraulic gear pumps can be classified according to several important criteria. These classification standards help distinguish different models based on design features, performance characteristics, and intended use.

1. Based on Gear Type

The type of gears used in the pump is one of the fundamental classification standards. The common gear types are:

External Gear Pumps:

In this design, two identical gears (drive and driven) mesh externally. The fluid is carried between the gear teeth and the pump casing. External gear pumps are widely used due to their simple structure and stable performance.

Internal Gear Pumps:

Internal gear pumps consist of a smaller internal gear rotating inside a larger external gear. A crescent-shaped partition separates the inlet and outlet. These pumps often produce quieter operation and better suction capability, making them suitable for sensitive applications.

Lobe and Helical Gear Pumps:

Some specialized gear pumps use lobed or helical gears to reduce noise and improve efficiency. Helical gear pumps, for instance, have angled teeth that enable smoother meshing.

2. Based on Displacement Type

Displacement refers to the volume of fluid the pump moves per revolution. Hydraulic gear pumps are classified into:

Fixed Displacement Pumps:

These pumps deliver a constant flow rate per revolution. They have a fixed geometry, which means the output volume cannot be changed during operation. Fixed displacement gear pumps are simple, reliable, and suitable for systems requiring steady flow.

Variable Displacement Pumps:

Though less common in gear pumps compared to other types like vane or piston pumps, some gear pumps allow variable displacement through adjustable internal components. This feature enables control over flow and pressure, improving system flexibility and energy efficiency.

3. Based on Mounting Type

The way a hydraulic gear pump is mounted also classifies it:

Flange Mounted:

These pumps have mounting flanges designed to attach directly to motors or engines. Flange mounting simplifies installation and is common in industrial settings.

Foot Mounted:

Foot-mounted pumps have base plates or feet for secure installation on machinery frames. This mounting method is typical when precise alignment with drive shafts is necessary.

Shaft Mounted:

Some gear pumps are mounted directly on drive shafts, allowing compact and direct power transmission without intermediate couplings.

4. Based on Drive Method

The driving mechanism classifies gear pumps into:

Mechanical Drive:

Driven by an external power source such as an electric motor, internal combustion engine, or gearbox.

Hydraulic Drive:

Some specialized gear pumps operate within hydraulic circuits where the power is transmitted hydraulically rather than mechanically.

5. Based on Pressure Rating

Hydraulic gear pumps are designed to operate under specific pressure limits, which influences their classification:

Low Pressure Pumps:

Typically operate under pressures up to 100 bar (around 1450 psi). These are suitable for light-duty applications where moderate pressure is sufficient.

Medium Pressure Pumps:

Designed for pressures ranging from 100 to 250 bar. These pumps are common in general industrial and mobile applications.

High Pressure Pumps:

Capable of handling pressures above 250 bar, these pumps are used in demanding environments such as heavy machinery and hydraulic presses.