Hydraulics versus pneumatics

components featured within hydraulic and pneumatic machines

Read time: 7 minutes | Updated on: 3 November 2022

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Hydraulics vs pneumatics: what are the differences?

What are hydraulics? What is a pneumatic system? We’ve designed this guide to help you answer those questions. Here, we’ll cover:

Hydraulics and pneumatics are both examples of fluid power. The difference lies in the fluid used and how those fluids are used. Only fluid power systems are capable of providing constant force or torque despite speed changes.

What does a hydraulic system do?

Instead of air, machines that use hydraulics rely on mostly incompressible liquid material under pressure to lift, hold and move goods. Examples include hydraulic or mineral oil - such as ethylene glycol - or water, just to name a few.

Advantages of hydraulics

Hydraulic power moves heavier loads with greater force than mechanical, electrical or pneumatic fluid power systems
Ease and accuracy of controlling the system by levers and push buttons
Hydraulic oil and mineral oil systems generate large amounts of power
Uses fewer moving parts than some mechanical and electrical systems, which makes it more durable and less prone to break down

What does a pneumatic system do?

Pneumatic machinery and equipment use pressurised gasses, such as air, for moving and cooling applications. Pneumatic fluid power systems compress air, so movement is not instantaneous, as it is with hydraulics.

Advantages of pneumatics

Fluid air power is more cost effective than hydraulics – air is free
Pneumatic safety – system can be used in inflammable environments and does not
More power in a smaller and lighter unit compared to most other technology systems
Cleaner technology
Fluid used absorbs excessive force, which means fewer threats of damage to equipment

What are the components of hydraulic machines and pneumatic machines?

Hydraulics - Hydraulic systems can be complex depending on its use, but generally, these are the basic components:

Reservoir – contains the liquid, most commonly, hydraulic oil
Pump – forces the liquid through the system
Motor – electric power source to drive the pump
Valves – controls the liquid’s direction, pressure and flow rate
Actuator – converts the liquid’s energy into mechanical force or torque
Piping – carries the liquid from one area to another

Pneumatic machines

Pneumatics - Pneumatic systems can range from simple air-driven pistons to equipment with multiple actuators for mining. Generally, the most common components include:

Air compressor – compresses normal air to a higher PSI (pounds per square inch)
Air reservoir – stores the pressurized air created by the compressor
Valve –controls the airflow so that the air is released at the right pressure level for the pneumatic equipment being used
Actuator – converts the energy stored into kinetic energy
Cylinder – generates motion and force from air pressure
Feed lines or hose pipe – supplies compressed air to components

Do pneumatic cylinders need oil?

That depends on your system. Older systems typically use a lubricant oil that provides airline lubrication. The oil’s low viscosity allows it to aspirate to form a mist. It’s this mist that provides the lubrication for not only cylinders, but valves, tools and motors. Most of today’s systems have the advantage of more advanced materials, such as nitrile seals on cylinders and valves, making lubricant unnecessary.

When do you use hydraulics or pneumatics?

Simply put, applications of hydraulic devices are best for when higher force and heavy lifting is needed. Use pneumatics for mechanical and lighter engineering needs. This table shows some examples of how each is used:

Hydraulics and pneumatics

Application	Hydraulic system examples	Pneumatic system examples
Construction equipment – lifts and lowers	x
Dishwashers – increase water pressure	x
Office chairs – lift and lower seat	x
Airplanes – adjust wings and extend landing gear	x
Vehicle brakes and steering – reduces effort needed by drivers	x
Mining tools – compressed air acts as source of energy for power tools		x
Exercise equipment – cylinder creates resistance		x
Dental drills – safe for patients (no chemicals or toxins)		x
Automated production equipment – powers tools on assembly lines		x
HVAC controls – send signals and control the devices to trigger action		x

Why is hydraulic and pneumatic system maintenance important?

The most important reason is safety. Pressurised hydraulic fluid that suddenly escapes presents the threat of explosive velocity.

Another hydraulic safety issue concerns the harm that faults can cause with unexpected movement by sharp, heavy equipment, injuring those nearby. Proper maintenance can not only ensure safety, but also reduce downtime and with it, costs.

Make sure you keep your hoses free from damage with the right protection, especially if you’re using them in industrial applications where movement is involved. Spiral wrap hose protectors and hose wear protectors are just two examples of solutions that can prolong the life of your hoses.

Keep in mind that fluid power hydraulic and pneumatic systems are low maintenance, with pneumatics even more so. Pneumatic safety precautions involve ensuring hoses are free from damage. Old or fraying hoses leak air, which causes equipment to malfunction.

That, in turn, can cause serious harm to users, which is why you also need to minimise hydraulic leaks. See more protection for pneumatic and hydraulic systems.

You should also use the appropriate threaded caps and plugs to avoid the risk of contamination. View our range here.

Protecting your hoses

To learn more about hose protection for your hydraulics and pneumatics systems, don’t miss:

Choosing the right components for pneumatic and hydraulic systems can also prolong the life of your equipment. Be sure to see our range here.

Download free CADs and try before you buy

Download free CADs and request free samples, which are available for most of our solutions. It’s a great way to ensure you’ve chosen exactly what you need for your pneumatic and hydraulic applications.

If you’re not quite sure which product will work best for your pneumatic system or hydraulic system, our experts are always happy to advise you. Whatever it is you need, you can depend on fast despatch.

Request your free samples or download free CADs now.

Questions?

Email us at sales@essentracomponents.co.uk or speak to one of our experts for further information on the ideal solution for your application 0345 528 0474.