The difference between gear oil pump and rotary pump

Gear oil pumps and rotary pumps are common positive displacement pumps, mainly used for transporting liquids such as lubricating oil, fuel, hydraulic oil, etc. However, they have limitations in structure, working principle, and applicable scenarios

There is a significant difference. The following are the main differences between the two:

1.  Structure and Working Principle

Gear Pump

Structure : Composed of a pair of meshing gears (driving gear and driven gear) and a pump housing, usually designed with external meshing.

Working principle:

When the gear rotates, a low-pressure area is formed on the side where the meshing teeth separate, and liquid is sucked in.

The liquid is carried to the discharge side by the gear, and the gear mesh squeezes the liquid, forming a high-pressure output.

Typical type : External gear pump (most common).

Rotor Pump

 Structure : Composed of a pair of specially shaped rotors (such as inner and outer rotors), with various rotor shapes (such as cycloid, double blade, triple blade, etc.).

Working principle:

The rotor is non contact engaged inside the pump casing, and the suction and discharge of liquid are achieved through the volume change between the rotors.

Common types include internal meshing cycloidal rotor pumps (such as Gerotor pumps), cam rotor pumps, etc.

 Rotary pump :

High viscosity liquid transportation (such as asphalt, resin, paint).

Food/pharmaceutical industry (sanitary rotary pump).

High pressure precision systems (such as automotive oil pumps, fuel injection systems).

4.  Summary of advantages and disadvantages

Gear oil pump :

Advantages: Simple structure, low cost, and easy maintenance.

Disadvantages: High noise, obvious flow pulsation, not suitable for high viscosity media.

 Rotary pump :

Advantages: Smooth operation, low noise, suitable for high viscosity media.

Disadvantages: Complex structure, high cost, and high requirements for machining accuracy.

5.  How to choose

 Choose gear oil pump : Limited budget, insensitive to noise, and capable of transporting low viscosity liquids.

 Choose rotary pump : Requires stable flow, handling high viscosity media, and limited space (such as automotive oil pumps).

In practical applications, it is necessary to comprehensively consider flow rate, pressure, medium characteristics, and environmental requirements. For example, car engines often use rotary pumps (pendulum type) to balance compactness and efficiency,

Gear oil pumps are commonly used in industrial lubrication systems.