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What Are Hydraulic Pumps Used For?

New hydraulic pump for truck closeup isolated on white background. Spare parts.

Hydraulic systems are used in a wide range of applications to do all types of laborious work that would otherwise be difficult to do manually. Hydraulic systems can be found in heavy construction equipment, manufacturing equipment, agricultural equipment, aerospace equipment, healthcare equipment, and more!

Hydraulic systems are a part of everyone’s daily lives in one way or another. They use hydraulic pumps, motors, and other components to push hydraulic oil through the system to create hydraulic energy via fluid power. Once this fluid power reaches cylinders in the system, it is converted into mechanical energy to perform the desired operations, such as raising and lowering a crane.

Some of the more common applications where you can find hydraulic systems include:

  • Braking Systems in Vehicles
  • Aeroplanes
  • Theme Park Rides
  • Lifts
  • Escalators
  • Auto Repair Lifts
  • Vehicle Jacks
  • Adjustable Height Chairs
  • Filling Station Fuel Pumps
  • Bath Lifts
  • Snowploughs
  • Robotics
  • Automated Manufacturing Machines
  • Trains
  • Boats and Ships
  • Tanks and Armoured Vehicles
  • Fork Lifts
  • Dump Lorries
  • Cranes
  • Rubbish Lorries / Trash Collection Lorries
  • Agricultural Tractors and Implements
  • Excavators
  • Backhoes
  • Mowers
  • Hedge and Verge Cutters
  • Forestry Equipment
  • Lorry and Truck Tippers and Cranes

This list is just a small sampling of the different types of devices, components, and equipment that use hydraulic systems in some manner to provide assistance and perform the desired tasks, such as steering or lifting. Hydraulic systems are even used in hydrostatic transmissions and powerpacks.

How Do Hydraulic Pumps Work?

Hydraulic pumps work by converting mechanical energy into hydraulic energy. They are used to create flow and pressure in a hydraulic system. Here’s a simplified explanation of how they work:

  1. Mechanical Input: Hydraulic pumps are typically powered by an electric motor or an internal combustion engine. The mechanical input turns the pump shaft.
  2. Inlet Stroke: As the pump shaft rotates, it causes the displacement chamber (also known as the inlet side) to expand. This creates a low-pressure area inside the pump housing, allowing fluid to enter the pump through an inlet port or suction line.
  3. Fluid Intake: The low-pressure environment draws in fluid from a reservoir or another part of the hydraulic system.
  4. Outlet Stroke: As the pump shaft rotates, the displacement chamber compresses or shrinks. This reduces the volume of the chamber and increases the operating pressure, forcing fluid out through an outlet port.
  5. Fluid Output: The pressurized hydraulic fluid is then directed into the hydraulic system, where it performs various tasks such as lifting heavy loads or operating machinery.
  6. Return Stroke: After the fluid is discharged from the pump’s outlet, the displacement chamber expands again (similar to step 2), creating a low-pressure area. This allows for another fluid intake cycle (step 3) to begin.

It is important to note that there are different types of hydraulic pumps, including gear pumps, vane pumps, and piston pumps. The specific design and operation may vary slightly between pumps, but the basic principles above still apply.

Overall, hydraulic pumps play a crucial role in generating the hydraulic power needed to operate various industrial and mechanical systems.

What Is the Function of Hydraulic Pumps?

Hydraulic pumps are essential for hydraulic systems to work correctly. The pumps are responsible for pushing and moving the hydraulic fluid through the system. This movement is what converts mechanical energy and motion into fluid power.

Hydraulic pumps work on positive displacement or by transferring a metered amount of fluid into the system. The system pressure helps regulate the necessary flow required to move the load up to the maximum permitted by whatever the system relief valve setting may be.

Additionally, the type of fluid used with the hydraulic system determines its overall effectiveness and how it can be applied to various devices, equipment, and machinery. Ideally, depending upon the application, you want to choose hydraulic fluids best suited to the application and system configuration.

Types of Hydraulic Pumps

There are several types of hydraulic pumps and variations in configurations that are used in hydraulic systems, including:

Gear Pumps

Hydraulic gear pumps have one gear attached to a drive shaft that is interlocked with another gear so the two rotate together. A gear pump may be external, with side-by-side gears rotating in opposite directions carrying the fluid from the low-pressure side to the high-pressure side, or internal, with one gear inside another, rotating in the same direction. 

Piston Pumps

Piston pumps, essentially, are pistons that move inside cylinders. The motion of the piston displaces hydraulic fluid to move it through the hydraulic system. There are several variations of piston pumps, including:

  • Axial Piston Pumps
  • Radial Piston Pumps
  • Positive Displacement Pumps
  • Variable Displacement Pumps
  • Fixed Displacement Pumps

Vane Pumps

Vane pumps use sliding vanes around a rotating shaft to move hydraulic fluid through the system. The vanes constantly adjust to maintain contact with the inside of the cam ring—an elliptical-shared ring inside the pump.

The fluid trapped between the vanes at the inlet side is forced out of the pump through the outlet side. As the fluid is forced out of the pump, it creates the fluid power and hydraulic energy to perform the desired tasks.

Vane pumps also come in a few different configurations, including variable displacement pumps and fixed displacement pumps.

Categories of Hydraulic Pumps

Just like there are several types of hydraulic pumps, there are also several different categories of hydraulic pumps, including:

Power source based:

  • Electric Pumps: These pumps are powered by electric motors.
  • Hydraulic Pumps: These pumps use fluid power to operate, usually driven by other hydraulic systems.

Pump action based:

  • Centrifugal Pumps: These pumps work on the principle of centrifugal force and are commonly used for low-pressure applications.
  • Rotary Vane Pumps: This type of pump uses rotating vanes to create pressure and is often used in automotive and industrial applications.
  • Screw Pumps: Screw pumps have helical rotors that move fluid along its axis, creating pressure. They are typically used for high-viscosity fluids or in oil drilling operations.
  • Gear Pumps: These pumps consist of meshed gears that trap and move fluid between the gear teeth, generating fluid flow and pressure. They are commonly used for simple, low-pressure applications.

Positive displacement types:

  • Piston Pumps: Piston pumps use reciprocating pistons to displace fluid to create fluid flow. They can be further classified into axial piston pumps (with pistons arranged parallel to the pump shaft) or radial piston pumps (with pistons arranged radially around the pump shaft). They are known for their high efficiency and versatility.
  • Vane Pumps: Vane pumps have vanes that slide in and out of slots in a rotor to generate flow and create pressure. They are known for their smooth operation and can handle low to medium pressures.
  • Lobe Pumps: Lobe pumps use rotating lobes instead of gears or pistons to create fluid flow. They are often used for pumping viscous fluids or in sanitary applications such as food processing.

Each category has many variations and sub-types, depending on specific designs and applications.

Tips for Selecting the Right Hydraulic Pump

Choosing the right hydraulic pump depends on factors like desired flow rate, pressure requirements, viscosity of the fluid being pumped, and system efficiency considerations. Here are some tips to help you make an informed decision:

  1. Understand Your Application: Clearly define the requirements of your hydraulic system, including flow rate, pressure range, temperature limitations, and fluid viscosity. Consider factors such as duty cycle, operating environment, and any specific features or functions required.
  2. Determine Pump Type: Based on your application requirements and budget considerations, determine which type of hydraulic pump (gear pump, vane pump, piston pump) would be most suitable. Each type has its advantages and disadvantages in terms of efficiency, durability, noise level, and cost.
  3. Calculate Flow Rate & Pressure Requirements: Determine the required flow rate and pressure for your system. This information will help you select a pump that can provide adequate performance.
  4. Size Appropriately: Ensure that the physical dimensions of the pump are compatible with your system’s space constraints. Consider factors such as mounting options, inlet/outlet port sizes, and overall footprint when selecting a hydraulic pump.
  5. Check Compatibility: Verify compatibility between the hydraulic pump and the hydraulic fluid being used.
  6. Seek Expert Advice: If unsure which pump is best for your application, consult a hydraulic expert and reputable supplier who can provide guidance based on their expertise and experience.

Final Thoughts

Dry Running Pumps

Hydraulic pumps perform a valuable function in helping to convert fluid power into mechanical energy to allow the hydraulic system to perform the desired functions. Since there are different types and variations of hydraulic pumps, it is essential to select the right ones that will best meet your hydraulic specifications and requirements to perform the necessary functions.

For further assistance in selecting the best high-quality hydraulic pumps, hydraulic motors, hydraulic cylinders, and other hydraulic parts and components for your hydraulic systems, please feel free to contact White House Products, Ltd. at +44 (0) 1475 742500 today!

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