Basics of Hydraulic Power Systems – How It Works?

Hydraulic Power Systems 1

Anyone who is a fan of hydraulic products will always love to know more about hydraulic power systems. Getting to know its basic components and the way they work is a good topic for hydraulic lovers. Hydraulic systems have taken the world by storm as they have impacts on almost every sphere of life. This fluid-power system is found everywhere including aircraft, construction equipment, automobiles, manufacturing industries, and even the office chair. The hydraulic power system is the answer to every task that includes lifting, moving, pushing, or splitting heavier objects. 

This article is the basic guide for hydraulic power systems that allows the readers to have a better look at the study of this system. When we use the term “System”, you can expect to go through the components the system is made up of. Find out more about this system in detail below.

What is Hydraulic Systems & Examples

When talking about hydraulic power systems, it’s important to address its definition first. The hydraulic system is a technology that uses hydraulic fluid pushed by a pump to create fluid power that can transfer energy from the electric motor to the actuator enabling something to work. In simple words, hydraulic power systems are the ones that make something perform using the systematically pressurized fluid. This system can be considered as an efficient way to create repetition of movement in different industrial applications. The pressurized fluid contained in a reservoir creates a force in every direction that allows users to lift or move heavier loads and do repetitive tasks most efficiently.

Hydraulic power systems are everywhere in our lives. The simplest of examples where the hydraulic system is found include office chairs that allow the users to rise/go down or lean forward/backward while sitting. Numerous sophisticated examples work based on hydraulic systems. Some of which include construction hydraulic types of machinery like excavators, cranes, forklifts; automobile applications like hydraulic brake, vehicle repair & maintenance machinery; aircraft control panels, amusement park rides, elevators, and many more.

How Hydraulic System Works

How Hydraulic System Works

The basic working principle of hydraulic power systems can be realized from its definition. However, we look to clarify more on how the system really works. The core idea behind these systems is that the hydraulic presses put pressure on a little amount of fluid to produce a much larger amount of power. The fluid here is contained in a vessel that has pressure applied on it from one side. The pressure then pushes it against the piston on the container’s other side. As a result, the energy is transferred into the piston allowing it to lift anything upward. The applied pressure doesn’t allow the fluid or the piston to move backward unless the pressure is withdrawn. In short, the system operator can keep on applying the pressure and lift anything as long as it’s required. For example, the forklift operator can keep its prongs raised using the piston until the pressure is taken off.

hydraulic system works

Types of Hydraulic System

Primarily there are two types of hydraulic systems; such as open-loop and closed-loop hydraulic systems. In the open-loop system, the actuating mechanism stays idle and the fluid flows without pressure. This type of system has a directional control valve and fluid flows from the actuator to the reservoir. Generating less heat is an excellent advantage of open-loop systems.

For the closed-loop system, the pump operates using fluid pressure where the fluid continuously flows between the pump and actuator without getting into the reservoir. This system also uses an additional pump known as a feed pump. Closed-loop hydraulic systems are a great choice for a precise response of the actuators.

Types of Hydraulic System 3


Basic Components of a Hydraulic System

The article gets deeper into the hydraulic system and discusses its basic components that make up the entire system. There are mainly four components of any hydraulic system that includes the reservoir, pump/compressor, valve, and actuator/cylinder.


The reservoir of a hydraulic system is the component that contains the volume of liquid. It is also responsible for transmitting heat into the system. The reservoir lets the solid contaminants in the fluid settle down. It also helps to remove air and other types of moisture from the contained fluid.

Hydraulic Valves 

The hydraulic valves are the mechanical apparatuses that regulate the flow of liquid in a hydraulic system. The valves consist of several spools that determine the direction of the fluid’s flow. They can be used to redirect pressurized liquid, control the level of liquid flow, or be actuated using different electrical or mechanical methods.

Types of Hydraulic System 1
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Hydraulic Actuators or Cylinders

The next component we’re going to talk about is the hydraulic actuators or cylinders. The actuators and cylinders aren’t the same things; but in hydraulic power systems, cylinders can act as actuators, especially as linear actuators. They are responsible for applying unidirectional force and creating linear motion. Actuators do that by taking the produced hydraulic power and converting it back to mechanical power.

Hydraulic Pump

A hydraulic pump is probably the most crucial component of a hydraulic system. This part of the system is the mechanical source that moves the fluid to the reservoir and converts the mechanical energy into hydraulic energy. It is there to generate a powerful flow to overcome the load-induced pressure at the outlet. The hydraulic pump is also the component that receives the most attention and the maximum number of questions. In this section, we’d also like to clarify some of these questions.

Hydraulic Pump Works

What are 3 types of hydraulic pumps?

Although the basic working principle for hydraulic pumps is the same, different types of pumps are available for different hydraulic applications. The three most typical hydraulic pumps that are commonly found are gear pumps, piston pumps, and vane pumps.

Does a pump increase pressure?

Not really, because the hydraulic pumps aren’t responsible for creating pressure, they only generate the flow of the fluid.

How do you calculate the hydraulic power of a pump?

The hydraulics of the pump is calculated as hydraulic flow multiplied by pressure. The equation can be considered as Hydraulic Power = (P [Pressure] x Q [Flow]) / 500. Here the power is calculated in kilowatts [kW], pressure in bars, and flow in LPM.

calculate the hydraulic power of a pump

More About Hydraulic Press

The hydraulic press is another topic that can’t remain unnoticed while talking about the basics of hydraulic power systems. It has been one of the earliest gifts of hydraulic systems that humankind is blessed with. Its groundwork had been laid by Pascal’s law which was later capitalized by Joseph Bramah to come up with his invention of the hydraulic press. There are some common questions encountered on this topic and we’ll be clarifying some of these here.

Hydraulic Press Review

What is a Hydraulic Press?

The hydraulic press is a piece of hydraulic machinery that uses a hydraulic cylinder to exert a comprehensive force. It utilizes a piston that acts as a pump to provide a large amount of mechanical force to a small area. This machine has paved the way for automating the manufacturing work leading to the industrial revolution. The machinery like the printing press, lifting machinery, or cutting equipment started utilizing hydraulic press and it soon became highly popular. Thanks to its large mechanical advantage that transformed the world of machines.

How much pressure should a hydraulic press have?

To determine the pressure a hydraulic press should have, you need to find the piston area from the piston diameter first. Then the amount of pressure in psi needs to be multiplied by the area of the cylinder in inches. To calculate the force in tons, the force should be divided in pounds by 2,000.

How do you increase hydraulic pressure?

The fluid flow into or out of the constrained amount needs to be metered to increase the hydraulic pressure. Adding the hydraulic fluid into the system to a certain volume can increase the pressure, whereas letting it out can decrease it.

What is the formula for hydraulic pressure?

The formula derived from Pascal’s law is known as the formula for hydraulic pressure. The equation that can determine the hydraulic pressure is P (Pressure) = F (Force)/ A (Area). We can say that the hydraulic pressure is calculated as the force per unit of area.

How do you control hydraulic pressure?

To control the hydraulic pressure, the flow of the fluid needs to be metered. It can be done using the P-Q or Pressure/Flow Control valves that can control either flow or pressure into the system.

How do you control hydraulic pressure

What do P and T stand for in hydraulics?

In hydraulics, P stands for Pump or the High-Pressure Input. Whereas, T stands for Tank or Low-Pressure Return to the hydraulic reservoir.

Hydraulic Fluid

If you’re wondering if hydraulic fluid refers to only water, then you need to be corrected. It is actually a liquid (not necessarily water) that acts as a medium to transfer power in hydraulic machinery. Besides that, some other mineral-oil-based liquids have become very popular as hydraulic fluids. In addition to transferring the energy, the hydraulic fluid is also responsible for lubricating the hydraulic system and staying self-cleaned. Nevertheless, hydraulic fluid has a major role to play in any hydraulic system. There are also some questions that this topic comes along and we’d like to answer some of these below.

What are the different types of hydraulic fluids?

There are different types of hydraulic fluid available for different hydraulic power systems. But, you’ll mostly get three of them—water-based fluids, petroleum-based fluids, and synthetic fluids available out there. Water-based fluids are good when it comes to fire resistance, however, they aren’t good lubricants and may evaporate at higher temperatures. The most popular hydraulic fluid today is petroleum-based ones. They offer excellent customization and allow different additives to be added. These fluids also act as rust & oxidation inhibitors and agents for anti-corrosion, anti-wear, and extreme temperatures. They are cost-effective as well. Synthetic fluids are customized and are perfect options in high-pressure and high-temperature hydraulic systems. They have fire resistance and lubrication properties as well. These fluids are slightly more expensive than the others.

What happens if you use the wrong hydraulic fluid?

The wrong hydraulic fluid can make you go wrong with the right viscosity of the fluid. This can lead to damage in the lubrication leading to the preterm failure of the major system components. Using the wrong hydraulic fluid can also increase power consumption, something that you wouldn’t really want.

Why do we use hydraulic oil instead of water?

We use hydraulic oils so widely instead of water for some good reasons. Hydraulic oils are more useful than water in many ways. Unlike water, they have lubricating properties and can prevent rust as well. The mineral oils also prevent corrosion which can potentially lead to pitting and unwanted leaks.

What liquid is usually used for hydraulic power?

In hydraulic systems, the liquid that is usually used for hydraulic power is petroleum-based hydraulic oil. It’s not only an excellent form of power transmission but also a great lubricant and anti-corrosion agent.


The hydraulic power systems are all around us today. Its study is something you can’t ignore. The basics of hydraulics will let you cope up with its continuous improvement and make contributions when needed. It will also allow you to be familiar with its working procedure and have a better understanding of real-world hydraulic applications. The idea behind the hydraulic system is quite simple, however, the evolution in this sector requires us to be updated and also contribute towards it for a quiet, safe, clean, and easy fluid-power technology.

Feature Image Source: Kent Fluid Power

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