---
title: How a Hydraulic System Works
description: "Learn how a hydraulic system works by reading this blog post. We discuss five major components: reservoir, pump, power source, valves and actuators."
---

[Brennan Industries Blog](https://blog.brennaninc.com)

# [How a Hydraulic System Works](https://blog.brennaninc.com/how-a-hydraulic-system-works)

 Written by [John Joyce](https://blog.brennaninc.com/author/john-joyce) | January 24, 2023

Hydraulic systems use pumps to push fluid from the reservoir through the system, converting mechanical energy into hydraulic fluid power. Certain [valves](https://brennaninc.com/product-category/instrumentation-valves/) help direct the flow of the fluid, others relieve pressure when needed.

Hydraulic systems are used in everything from construction and agricultural equipment, industrial machinery, trains, planes and automobiles. A hydraulic system performs significant work in many applications, such as:

- Deploying and retracting landing gear on planes
- Lifting heavy loads with cranes or earth-moving equipment
- Drilling wells in oil fields
- Turning shafts in industrial equipment
- Moving the ram in a forging press
- And many more

A hydraulic system is made up of five major components:

#1 - Reservoir  
The hydraulic reservoir holds the fluid and transfers heat from the system, causing unwanted contaminants to sink and forcing air and moisture to release from the fluid.

#2 - Pump  
The pump in a hydraulic system converts mechanical energy into hydraulic energy by the movement of the fluid. There are three primary kinds of hydraulic pumps, including:

1. Gear pumps – a type of positive displacement (PD) pump.
2. Piston pumps – a positive displacement pump, where the high-pressure seal reciprocates with the piston
3. Vane pumps – operate with a more constant flow pulsation

All of these styles are intended for specific applications, such as variable displacement vane pumps or bent-axis piston pumps. However, all hydraulic pumps work on the same principle: displacing fluid volume to an opposing load in order to create the necessary pressure to move the piston.

#3 - Power Source  
A comparatively small\* electric motor or other power source is required to drive the pump.

#4 - Valves  
Hydraulic [valves](https://brennaninc.com/product-category/instrumentation-valves/) are used to start, direct or stop fluid flow in the system. The valves in a hydraulic system are actuated by hydraulic, pneumatic, manual, electrical or mechanical controls.

#5 - Actuators  
Hydraulic actuators convert hydraulic energy to mechanical energy. This is typically done via a hydraulic cylinder converting hydraulic energy into linear motion OR a hydraulic motor converting hydraulic energy into rotary motion.

The hydraulic system is interconnected by hoses, tubes and/or pipes and fittings that transmit fluid from one component to another.

#### The Principle of a Hydraulic System

The principle of a hydraulic system is based on Pascal’s Law, which asserts: If pressure is applied to fluid in a hose, tube or pipe, it will transmit a force acting on a small area and generate a proportionally bigger force on a larger area/device, such as a piston within a cylinder. The piston rod moves due to the force of the pressure acting upon a cylinder, which will push, pull, press or lift something that requires exceptional force.

A very small hydraulic cylinder can create a large amount of force, especially when compared to electrical components. An alternative electrical system would necessitate a comparatively large\* electric motor, requiring much more power to provide the same amount of force as a hydraulic system.

To learn more about the different examples of hydraulic equipment that are found in the manufacturing sector, check out our BluPrint:

[View full post](https://blog.brennaninc.com/how-a-hydraulic-system-works)

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