Different Types of Hydraulic Pumps and Their Uses

A hydraulic pump is a device used to convert mechanical energy into hydraulic or fluid energy. These operating systems move the fluid continuously or/and discontinuously. During the process, pressure is created, which powers hydraulic machinery. This pressure is utilized in various tasks like lifting, pushing, and rotating the machinery components. Many manufacturing industries use various types of hydraulic pumps in everyday applications. 

What are the Types of Hydraulic Pumps?

With many options available in the market, it becomes essential to understand the difference between various types before making a purchase. 

• Non-positive Displacement Pumps: 

A continuous flow is produced by a non-positive displacement pump. Since it doesn’t have a strong internal seal to prevent slippage, its output fluctuates a lot as pressure changes. Non-positive-displacement pumps include propeller and centrifugal pumps.

• Positive Displacement Pumps:

A positive displacement pump functions by displacing liquid with every revolution. The flow rate in this pump is directly proportional to the number of revolutions. These pumps move only a fixed volume of liquid. 

In this article, we will talk about the types of positive displacement pumps.

1. Reciprocating Pumps:

A piston is used in this positive displacement pump to move the fluid to and fro. 

With the movement of the piston, the fluid is drawn into the pump and then forced out when the pressure is applied. 

Advantages:

• These pumps can handle high-pressure applications.
• These pumps function well with a wide range of fluids. 

Disadvantages:

• The reciprocating motion can make the entire process noisy.
• They are expensive.  

Suitability:

• Reciprocating pumps are best suited for high-pressure fluid transfer jobs. 

2. Rotary Pumps:

These positive displacement pumps trap the liquid between rotating components like vanes or screws and force it out of the pump. A steady flow is created during the process. 

Advantages:

• They provide a smooth and continuous flow.
• They have a simple design.
• They are highly efficient.

Disadvantages:

• These pumps are not suitable for handling abrasives.

Suitability:

• They are suitable for moving viscous liquids like oils and syrups. 

One of the most essential types of rotary pumps is the gear pump and the vane pump. Let us talk about it in detail:

(i) Gear Pumps:

Gear pumps are the most common type of hydraulic pump. They have fewer movable parts as compared to other types of pumps. These pumps have fixed displacement and are also known as positive displacement pumps. They function by joining the teeth of two gears which in turn creates a variation in fluid chambers and driving flow. With the gear turning, the space shrinks and the fluid is displaced. 

Advantages: 

• They are easy to service since they have fewer displacement parts. 
• They are 100% efficient
• They can function with a wide range of liquids including harmful chemicals, and therefore are suitable for various industrial settings.

Disadvantages: 

• They are not suitable for high flow rates.
• They can sometimes be noisy.

Suitability: 

They work best with high-viscosity fluids. 

(ii) Vane Pumps:

Vane pumps are best suited for low-pressure applications. They are compatible with a large number of vanes, including flexible vanes, rolling vanes, and external vanes. When the rotor is rotated, pressure is created, and the vane pushes the liquid to the other side.

Advantages:

• Vane pumps are self-priming.
• These pumps do not produce noise.

Disadvantages:

• They are less effective under high pressure.
• They do not function well with abrasive materials.

Suitability: 

They work best with low and medium-viscosity fluids. 

3. Variable Piston Pumps:

Variable piston pumps are designed to perform complex jobs. They are positive displacement pumps that use high-pressure reciprocating pistons to move fluid from one place to another. The pistons’ to-and-fro movement creates suction during the process, generating pressure. 

Advantages: 

• They can work with a variety of fluids. 
• They can work well for years.

Disadvantages:

• They are expensive.
• They are heavy.

Suitability: 

Piston pumps are the most suitable for high-pressure applications like manufacturing industries.  

There are two types of piston pumps- axial piston pumps and radial piston pumps. 

(i) Axial Piston Pump

They comprise a hydraulic pump with pistons arranged in a circle. The drive shaft rotates, and the piston moves up and down. The shaft speed is adjustable. They are used in many industrial applications. 

Advantages: 

• They can easily generate high pressures.
• They have high output pressure.

Disadvantages:

• They are not great with thick fluids.
• They can often overheat. 

Suitability: 

They are used for heavy-duty industrial applications.

(ii) Radial Piston Pump

In radial-piston pumps, the pistons are arranged radially in a cylinder block; they move perpendicularly to the shaft centerline. Two basic types are available: one uses cylindrically shaped pistons, and the other ball pistons. They may also be classified according to the porting arrangement: check valve or pintle valve. They are available in fixed and variable displacement and variable reversible (over-center) displacement.

Advantages:

• Their design is space efficient.
• They have low noise levels.

Disadvantages:

• They might be difficult to install.
• They are expensive.

Suitability: 

They are ideal for applications with high torques and low speed.

4. Plunger Pumps:

These pumps are similar to rotary piston pumps since they use reciprocating pistons. The difference is that the plunger pumps have fixed cylinder positions. 

Advantages:

• They are compact.
• They are durable.

Disadvantages:

• They require timely maintenance.
• They take up a lot of space due to their broad size.

Suitability:

Plunger pumps can function well under high-pressure conditions and high flow rates, so they are suitable for oil refineries, industrial cleaning plants, etc. 

Conclusion:

• Hydraulic pumps are machines that are used for various tasks performed in industrial settings like lifting, pushing, and rotating. 
• It is vital to understand the various types of hydraulic pumps for optimum performance.
• Look for multiple factors such as price, suitability, advantages, and disadvantages before you buy hydraulic pumps.

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