Machines Theory

Understanding hydraulic pump

Just as other pumping devices, the hydraulic pump is another great type used in hydraulic drive systems. It can be hydrostatic or hydrodynamic. Hydraulic pumps are sources of power for most dynamic machines. They have the ability to push large amounts of oil through hydraulic cylinders or hydraulic motors. In this manner, they convert the mechanical energy of the drive (i.e.,) into hydrostatic energy (i.e., flow, pressure).

Hydrostatic pumps are positive displacement pumps while hydrodynamic pumps are fixed displacement pumps. All hydrostatic pumps work on the principle of Pascal’s law. Hydraulic machines can be equipped with a pump in order to perform different tasks such as lift, lower, close, open, or rotate components. this will be further explained!

hydraulic pump

Today you’ll get to know the definition, applications, components, function, types, and working principles of a hydraulic pump. You’ll also get to know the advantages and disadvantages of this hydraulic pump.

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What is a Hydraulic pump?

A hydraulic pump is a mechanical device that converts mechanical power into hydraulic energy. With enough power generated the flow pressure induced in the load is overpower. Vacuum is created at the pump inlet when the hydraulic pump operates. This forces the liquid from the reservoir into the inlet line to the pump. It then delivers it to the pump outlet by mechanical action. It then forces it into the hydraulic system.

Additionally, to the definition of hydraulic pump, it is any device that you can put force into to create pressure, which will create flow in return. A basic hydraulic pump is the hand pump, which is used for low-power applications. in most situations, a prime mover is not available or too expensive, making the hand pump to be used.

Hand hydraulic pump can be used for auxiliary power, such as releasing a hydraulic brake on a tractor-towed farm implement. Hand hydraulic pumps are used as the primary hydraulic source, such as with hydraulic power tools or benchtop. Hydraulic hand pump applications are very slow even though pressure of more than 10,000 psi and greater can be applied.

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Applications of hydraulic pump

The applications of hydraulic pumps include excavators, cranes, loaders, tractors, vacuum trucks, forestry equipment, and graders. Dump trucks, mining machinery, etc. also make good use of hydraulic pumps. Hydraulic pumps are also used on every conceivable mobile or industrial hydraulic machine. Although mobile application makes use of hydraulic pumps more prolifically than it does on industrial machines. This is because electric actuators are generally not employed on mobile machinery. Hydraulic pumps are still in use in industrial environments.

Injection molding machines, presses such as shear, stamping, or bending, etc.) material handling, lifts, conveyors, mixers, forklifts, pallet jacks, foundries, steel mills, slitters, etc. are powered by a hydraulic pump.

With the above-listed applications of hydraulic pumps, you can derive its function. Now we can see the hydraulic pump is just a component of a hydraulic system. it takes mechanical energy and converts it into fluid energy in the form of oil flow. This mechanical energy is gotten from what is known as the prime mover (a turning force).

Hydraulic pump diagram:

hydraulic pump components
Components of hydraulic pump

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Types of hydraulic pump

Below are the various types of hydraulic pumps for various applications.

Gear pump

Gear types of pumps are the most common design. It is characterized as having fewer parts, easy to service, more tolerant of contamination when compared with other designs. Also, gear pumps are relatively inexpensive. These types of pumps are fixed displacement but are also called positive displacement pumps. That is, the same volume of flow is produced with each rotation of the pump’s shaft. Gear pumps are rated based on their maximum pressure rating, cubic inch displacement, and maximum input speed limitation.

Piston pump

These types of pumps are often used when high operating pressure is needed. Piston pumps have the capacity to withstand higher pressures than the previously explained one. However, this pump has a higher initial cost and lower resistance to contamination, and increased complexity. Well, its complexity falls to the equipment designer and service technician to understand and ensure the pump is working perfectly with its additional moving parts. Stricter filtration requirements and closer tolerances must also be considered.  Piston types of pumps are often used in truck-mounted cranes but are also found in other applications.

Vane pump

Vane pumps are commonly used on utility vehicles like aerial buckets and ladders. Although, these days they are not common on these mobile (truck-mounted) hydraulic systems. Gear pumps are widely accepted and available.

Clutch pump

A clutch pump is a small displacement gear pump, containing a drive belt, electromagnetic clutch. It is just like the ones found in the car’s air conditioner compressor. The clutch types of pumps are often used where a transmission power take-off aperture is not provided or is not easily accessible.

Dump pump

Dump types of hydraulic pumps are the most popular among the above-listed ones. They are commonly used in dumping applications from dump trailers to tandem axle dump trucks. This pump is specifically designed for one application, which is dump trucks. It cannot be used for other common trailer applications like floor and ejected trailers. Although an application can be design to use this pump. The only thing that separates this pump from the gear pump is its built-in pressure relief assembly. Also, an integral three-position and three-way directional control valve separate them. dump pumps are not suitable for continuous-duty applications because of their narrow, internal paths and the subsequent likelihood of excessive heat generation.

Refuse pump

These types of pumps are designed for refuse equipment. It includes both dry valves and Lives Pak pumps as they conserve fuel in OFF mode. They have the capacity of providing full flow when they operate. Special valving is equipped on these pumps despite their designs based on the standard gear pump.

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Working principle

The working principle of hydraulic is much easy understand but can be slightly different since there various types available for various purposes.

For gear pumps that are used in open center hydraulic systems, oil is a trap in the areas between the teeth of the pump’s two gears. The body of the pump will then transport it around the circumference of the gear cavity. It will then force it through the outlet port as the gears mesh. Inside the brass alloy thrust plates or wear plates, a small amount of pressurized oil pushes the plates tightly against the gear ends to improve pump efficiency.

And for piston pump, a cylinder block containing pistons that move in and out is housed within a pump. The movement of these pistons draws oil from the supply port and then forces it through the outlet. The length of the piston’s stroke determines the angle of the swashplate, which the slipper end of the piston rides against. As the swash plate remains in one position, the cylinder block, encompassing the pistons, and rotates with the pump’s input shaft. The pump displacement is then determined by the total volume of the pump’s cylinders. In these types of pump fixed and variable displacement designs are both available.

Watch the video below to learn more on the working of hydraulic pump:

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Hydraulic pump is a great source of pumping device for many applications today, even though it powers most dynamic machines. In this article, we’ve explained the definition, applications, function, types, and working of a hydraulic pump.

I hope you got a lot from this post, if so, kindly share it with other technical students. Thanks for reading! See you next time.

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