Hydraulic pumps are used to circulate hydraulic fluid (usually oil) through pipes under high pressure to move hydraulic actuators. Hydraulic actuators are usually hydraulic cylinders or motors.

Gear Hydraulic Pump

Gear pumps have very few moving parts. They consist of two intermeshing gears. These pumps have a constant flow rate. Their working pressure is generally between 50 and 210 bar. The operating speed of the gear pump is the highest of all pumps, up to 3000-6000rpm.

advantage:

cheap price

fixed displacement

shortcoming:

Volumetric efficiency is very low

There are two types of gear pumps: external gear pumps and internal gear pumps.

External gear pump:

In an external gear pump, only one gear, the drive gear, is connected to the drive. The other gear, the driven gear, rotates in the opposite direction, so the teeth of the rotating gear are locked to each other.

There are also double external gear pumps, which combine two gear pumps driven by the same coupling shaft. The advantage of a double external gear pump is that it can power two independent hydraulic circuits, as well as provide more flow to one circuit.

Internal gear pump:

There is an eccentric internal gear and an external gear also called a crown gear.

When the external gear rotates, a volume is created between the gear profile and the external gear teeth attached to the gearbox wall.

When the two wheels disengage, the product is sucked away.

advantage:

The internal gear pump is very quiet

Provide continuous traffic

Piston Hydraulic Pump

Hydraulic piston pumps handle very large flows at high pressure. It is operated by a piston that moves back and forth continuously. The piston seals well and can operate at high pressure with low fluid leakage.

advantage:

Provides the best overall volumetric efficiency

Provide the highest pressure

Reliable performance

with high power density

Available in variable displacement and fixed displacement models

shortcoming:

is the most expensive hydraulic pump

There are two types of piston mounting: radial and axial.

Axial installation:

The design of axial piston pumps is based on the swash plate principle or arc shaft design.

In the case of a swashplate, the rotating piston is supported by the swashplate; the angle of the swashplate determines the piston stroke.

In a crankshaft configuration, the amount of displacement depends on the angle of rotation: as the shaft rotates, the piston moves in the cylinder.

Radial installation:

Radial piston pumps are available in two different configurations.

Eccentric Cylinder: The piston rotates within a rigid outer ring. Eccentricity determines the stroke of the piston.

Eccentric Shaft: A rotating eccentric shaft causes radial oscillatory motion of the piston.

advantage:

Radial piston pumps can be equipped with several different independent outputs.

Rotary Vane Hydraulic Pump

This type of pump has rectangular vanes that fit in radial grooves in the rotor. This allows the vanes to move radially.

advantage:

Usually offers better volumetric efficiency than gear pumps.

Produces less noise while maintaining high speeds (up to 3000 rpm).

Available in variable displacement and fixed displacement models

When the hydraulic pump is variable displacement, the flow can be reduced if necessary, thereby reducing energy consumption.

shortcoming:

Rotary vane pumps are more expensive than gear pumps (and less expensive than piston pumps).

They are also fragile because the blades are subject to bending stresses due to discharge pressure, and are also fragile.

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