gear pumps

Example of gear pumps

Gear pumps are important components in various fluid transfer systems and find wide application in different industrial sectors. In this article, we propose to take a closer look at the principle and modes of operation, designs, materials, and key parameters of gear pumps. This will help to better understand their functionality and features in different aspects.

Therefore, gear pumps are a type of pumps used for fluid transfer through the interaction of rotating gears. Depending on the design, gear pumps can be classified based on the following criteria:

  1. Engagement type: a) external gear pumps; b) internal gear pumps.
  2. Shape of gear teeth: a) spur gear pumps; b) helical gear pumps; c) herringbone gear pumps.
  3. Number of rotors: a) two-rotor pumps; b) multi-rotor pumps.
  4. Number of rotor pairs in the pump: a) single-stage pumps; b) multi-stage pumps.
  5. Ability to adjust capacity: a) variable displacement pumps; b) fixed displacement pumps.

External gear pumps consist of two gears positioned parallel to each other. When the drive and driven rotors spin, a vacuum is created on the inlet side, as a result of which the liquid under atmospheric pressure fills the cavities between the teeth and moves from the suction chamber to the discharge chamber. On the outlet side, as the teeth engage, the liquid is pushed into the system.

Internal gear pumps are composed of a large and a small gear. The small gear serves as the driving gear and rotates the external gear (driven gear). When the gears rotate, a vacuum (void) is created on the suction side of the pump. The liquid enters the space between the teeth of the driving and driven gears and then flows into the discharge chamber.


The design of gear pumps includes a casing (body) that holds all the pump components. The working mechanism consists of two or more gears – one driving gear and one or several driven gears. The shaft of the driving gear transfers the rotation from the driving gear to the driven rotors. The gears have a special tooth profile that allows them to engage with each other and move the working fluid. The gears can be internal or external. Internal gears are located inside the external gears and engage with their teeth. Seals play an important role in preventing leakage of the working fluid. They are located at the contact points between the housing, gears, and shaft. Seals can be in the form of rings, sleeves, or mechanical seals, which ensure the pump’s tightness and prevent fluid leakage.


All pump components can be made from various materials:

Pump Casing: The pump casing can be made of metal materials such as cast iron, steel, stainless steel, or special polymer materials. Cast iron is typically used in heavy industrial conditions due to its high strength and resistance to aggressive environments. Steel and stainless steel are widely used in various applications due to their strength and corrosion resistance. Special polymer materials provide corrosion resistance, thermal insulation, and make the pumps lighter and more convenient for transportation and installation.

Gears: Gears can also be made of metal materials such as steel or bronze, or special polymer materials. Steel gears are commonly used in demanding conditions where high strength and wear resistance are required. Bronze and polymer gears are known for their good lubrication properties and lower noise levels.

Shaft: The pump shaft can be made of various grades of steel. The choice of material depends on the operating conditions, such as pressure, temperature, and chemical resistance.

Seals: Seals, which prevent the leakage of the working fluid from the pump, can be made from different materials such as rubber, polytetrafluoroethylene (PTFE), or silicone. The choice of material depends on the chemical composition of the fluid, temperature, and other factors.


Gear pumps can operate in various modes depending on the system requirements. The main operating modes include:

Constant Pressure: In this mode, the pump maintains a constant pressure of the working fluid. It is used, for example, in hydraulic or pneumatic systems where a stable pressure is necessary for proper operation.

Constant Displacement: In this mode, the pump delivers a constant volume of the working fluid per revolution. It is employed, for instance, in cases where a consistent flow rate of fluid is required for precise metering.

Variable Displacement: In this mode, the pump provides a variable volume of the working fluid depending on the shaft speed. This mode is used when it is necessary to regulate the flow rate of the fluid or gas in the system.


Gear pumps have several parameters that should be considered when selecting and using them. One of them is the maximum pressure that the pump can generate. This parameter should meet the requirements of the system in which it will be installed. It is measured in megapascals (MPa) or kilograms-force per square centimeter (kgf/cm²). Another important parameter is the pump’s capacity, which is determined by the volume of fluid it can transfer within a certain time. It is measured in liters per minute (l/min) or cubic meters per hour (m³/h). The maximum safe operating temperature is also crucial. It is important to ensure that the pump materials can withstand the working temperatures.

However, it is essential to consider other characteristics as well, such as connection dimensions, working environment, viscosity of fluids, etc., which significantly impact the operation and utilization of the pump in a specific system.


The applications of gear pumps are highly diverse and encompass a wide range of industries and technologies. Here are more specific examples of their usage:

Textile Industry:

  • Accurate dosing and delivery of polymer solutions in the production of synthetic fibers or cellulose solutions in the manufacturing of artificial fibers (viscose).
  • Transfer of plastic polymer mass through an extruder where it is transformed into fine fibers. This process helps create artificial fibers of varying lengths and thicknesses.
  • Transfer of dyes and pigments during the dyeing process of synthetic and artificial yarns.
  • Dosing of resin or polymer solution in the stretching and spinning processes of synthetic fibers. This ensures a stable and controlled supply of material required to obtain fibers with the desired strength and structure.

Mechanical Engineering:

  • Lubrication of bearings, cooling fluid transmission, and lubrication systems in various machinery and equipment, including lathes, presses, industrial robots, and metalworking machinery.
  • Supply of working fluid in hydraulic systems used in pneumatic and hydraulic presses, lifting mechanisms, automatic press lines, and other hydraulic devices.

Chemical Industry:

  • Transfer of various chemical substances, including high viscosity liquids, aggressive substances, and chemical solutions.
  • Accurate dosing of different chemical substances in chemical processes, research laboratories, and the production of paint and coating materials.

Oil and Gas Industry:

  • Extraction of oil and gas, as well as the transfer of these substances through pipelines.
  • Mixing, transfer of solvents, equipment lubrication, and pressure regulation in oil and gas processing operations.

Pharmaceutical Industry:

  • Transfer of various components and solutions used in the production of pharmaceuticals.
  • Dosing and transfer of different substances and reagents in research laboratories and pharmaceutical research.

Energy Sector:

  • Transfer of cooling fluids and heat carriers in solar energy systems for the efficient operation of solar collectors and energy storage systems.
  • Lubrication and cooling of wind turbine equipment, as well as the transfer of hydraulic fluid in blade adjustment systems of wind turbines.

Processing Industry:

  • Plastic processing extensively utilizes gear pumps for the transfer of molten plastic into molding machines and production lines.
  • Transferring various solutions and reagents used in plastic processing processes.

The application of gear pumps in these industries helps ensure efficient and stable operation of processing and manufacturing processes, contributing to the production of high-quality goods.

Gear pumps are crucial technical components that facilitate efficient liquid transfer across various industries. When selecting this type of pump, it is essential to consider the specific needs of the system. The diversity in designs, materials, and technical features impacts their reliability and productivity. Our company is ready to assist you in choosing the right pump, taking into account all the requirements and providing appropriate parameters and specifications. If you need consultation or support in finding the optimal solution, please don’t hesitate to contact us at +380 (99) 102-27-64 or email us at