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Hydraulic Pump Types

collage of hydraulic pumps

Hydraulics are essential in many industrial applications; they use mechanical energy to force liquid into a system. Within the category of hydraulics, there are many different types of hydraulic pumps that accomplish various tasks within industrial fields. Let’s take a look at some of them.

Axial Piston Pumps

An axial piston hydraulic pump is also a positive displacement pump. Axion pumps have cylinders that are assembled around a central axis (cylinder block). Within each cylinder, there are pistons which will attach to a swashplate or wobble plate. These swashplates then connect to the rotating shaft, which moves the pistons and pulls them in and out of the cylinders.

Axial piston pumps can also be made into variable displacement piston pumps, which provide more control over speed. In variable pumps, the swashplate is used to set the depth of the pistons, which creates a length variation to affect the discharge volume. This design helps maintain constant discharge rates in industrial applications.

Radial Piston Pumps

Another hydraulic pump type is the radial piston pump. As the name suggests, the pistons are arranged along the radius of the cylindrical block, which includes the pintle and rotor. The rotor powers the pistons through the cylinders and forces hydraulic fluid in and out of the cylinder.

Both axial and radial piston pumps are used for high-operating pressures as they can withstand much higher pressures than hydraulic pump types. They are often used in ice and snow control applications, as well as on truck-mounted cranes.

Rotary Vane Pumps

A rotary vane pump is also a type of positive displacement pump. It uses rigid vanes rather than the rotor hubs. These vanes are placed around an eccentric rotor device, which moves around the inside wall of the housing container. This movement forces the hydraulic fluid through the discharge port, and, in some applications, can be adjusted to align with the rotational axis of the motor.

Vane pumps are often used in utility vehicles but have lost popularity over the years in favor of gear pump hydraulic systems. However, they used to be very common in aerial buckets and ladders along with other mobile, truck-mounted hydraulic applications.

External Gear Pumps

Gear pumps have become the most common hydraulic pump type that’s used in industrial applications today. The gear pump has fewer moving parts than piston or vane pumps, which makes it easy to service and relatively inexpensive compared to other hydraulic pumps. They are also less likely to be contaminated during use.

An external gear pump uses two gears on the outside of individual shafts to aid in movement and push both thin and thick fluids through the gears. These external pumps are commonly used in fixed-displacement applications and high-pressure environments.

Internal Gear Pumps

Internal gear pumps place gears on the insides of the shafts rather than on the outside as found in external gear pumps. That makes them self-priming and non-pulsing, and can even be run without liquid for short periods of time—although they can’t be left dry for too long.

Additionally, internal gear pumps are bi-rotational, meaning that one can be utilized to both unload and load devices. And, with only two moving parts, they are considered to be one of the most reliable types of hydraulic pumps.

Which Type of Hydraulic Pump Has the Highest Volumetric Efficiency?

Volumetric efficiency is the amount of output the pump actually produces as a percentage of its theoretical production. The higher the percentage the more efficient the pump.

Among the factors affecting volumetric efficiency are leakage and fluid compressibility (ability for volume to be reduced under pressure). These issues can cause the pump to lose efficiency and waste energy as that energy converts to heat.

Of the four major kinds of hydraulic pumps, the rotary vane pump offers the highest volumetric efficiency.

Have Questions? Call Panagon Systems Today!

Still have questions about hydraulic pumps or their parts and repairs? Contact Panagon Systems today. We’ve been a leading hydraulic pump manufacturer in the U.S. for over two decades, and can help you find the best solution for your application. You can view our full line of pumps here. To request a consultation or quote, please fill out our online form.


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