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Hydraulic gear pumps

A key component of many hydraulic systems, hydraulic gear pumps are used in a wide variety of industrial, automotive, aerospace and other applications. In fact, this variety of fixed-displacement pumps offers constant fluid flow and high pressure to power hydraulic machinery and equipment. In this article, we will explore in detail how hydraulic gear pumps work, how they are constructed, their advantages and limitations, and the different applications for which they are used.

What is a hydraulic gear pump ?

POMPE HYDRAULIQUE A ENGRENAGES: COMMENT CALCULER LE DEBIT ? -

A hydraulic gear pump is a pump that uses gears to transfer mechanical energy into hydraulic energy. It generally consists of a casing, at least two rotating gears, and a system of seals to contain and pump the hydraulic fluid.

These pumps are often used for applications requiring constant liquid flow and high pressure, such as machine tools, presses, lifting systems, and aeronautical and automotive equipment.

What are the different types of hydraulic gear pump ?

There are two gear pairs, external gear pumps and internal gear pumps.

- External gear pump

TECH-POMPES - Pompe à engrenage externe

External gear pumps have two gears with teeth that span the circumference. These gears mesh while rotating in opposite directions. The driving wheel is directly subjected to the movement of the motor, while the driven wheel is subjected to the action of the driving wheel through gearing.

When the gearwheels separate in front of the inlet port, the vacuum created is directly occupied by the fluid in the reservoir. The fluid is then transported by the teeth along the walls of the pump body into the cavities formed by the two supports. Axial sealing is ensured by plates that prevent the fluid from spilling over the sides. The fluid is then conveyed to the discharge port where it is evacuated.

External gear pumps are effective for operations such as greasing, lubrication, plastics extrusion and many more. However, they can be noisy and subject to wear, and are not suitable for all applications.

- Internal gear pump

Pompe à engrenage interne PGH 3xIt consists of a pigand an internally toothed rotor covering the circumference of the pump casing.

As the rotor rotates, it automatically drives the pinion, creating a suction space for the fluid just past the inlet port. The fluid then moves around a fixed crescent, forming cells with the rotor and pinion on either side, before being led to the discharge port.

Internal gear pumps are often used in the automotive industry to lubricate engine parts. Their volumetric efficiency is higher than that of simple gear pumps.

It is ideal for handling low-viscosity fluids that require a constant flow at high pressure, such as feeding a diesel burner system.

What are the advantages of gear pumps?

Gear pumps are very economical pumping devices. This is because these hydraulic pumps have very few moving parts, making them difficult to wear out or damage

Compact and designed with a simple mechanical system, they have the advantage of being able to handle fluids of all types, whether thin, thick or even viscous, whether food, petroleum or other.

It's true that hydraulic gear pumps can't compete with piston pumps in terms of pressure generated, but they do offer higher pressures and flow rates than vane pumps.

What are the limitations of gear pumps ?

Défaut principal des pompes à engrenage externe [Hydraulique : De la mécanique des fluides à la transmission de Puissance]

Hydraulic gear pumps are fixed displacement pumps whose flow rate depends on the drive shaft. This means that the motor speed must be variable in order to adjust the flow rate. This differs from other types of hydraulic pump, which allow the flow rate to be adjusted either by positioning the pistons or by adjusting the vanes.

Hydraulic gear pumps are not suitable for high-pressure conditions in excess of 250 bar due to discharge pressures caused by internal leakage, which directly affects volumetric efficiency.

External gear pumps do not allow fluids to pass through the centre because they are locked by the teeth of the two gears crossing. No fluid can turn around, which can cause the gears to jam and damage the system if a large particle gets stuck.

Internal gear pumps have more friction, which leads to increased wear on the mechanical part, particularly if they are used with abrasive fluids. Internal gear pumps are mainly used for medium and low pressures and flow rates of 25 l/min or less.

What are the applications for hydraulic gear pumps ?

Hydraulic gear pumps are versatile pieces of equipment used in a wide range of applications.

In the energy sector, these pumps are used to produce, transport and distribute hydraulic energy. Hydraulic gear pumps are also used in agricultureto pump water from the fields and for drinking water production and irrigation.

Pompes à engrenages - Pompe volumétrique à engrenage pour fluides

In the industrial sector, they are used in various industries such as water extraction, transport and distribution, water purification, pumping waste from landfill sites, and for handling raw materials, finished products or spare parts. They can also be used to pump oil in refineries.

Hydraulic gear pumps are also used in the production of natural gas, oil and electricity.

In the marine sector, these pumps are used for ship propulsion.

Finally, hydraulic gear pumps are used in the defence industry for the manufacture of weapons and in civil protection.

Still on the same theme

- Piston pumps

- Vane pumps

- Screw pumps

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