Pneumatics

Pneumatics is the technology of controlling pressurized gases to create force and motion. Parker Pneumatics enable and improve machinery performance.
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How to Innovate to Address the 4C Challenge for Rail - Parker Hannifin Pneumatic Division EuropeLooking at a complete system within the vehicle along with all its interfaces from a completely clean sheet will give us the opportunity to question, review and potentially improve that system (in this example, rail) utilising the latest technology and manufacturing advances.
  The 4C challenge
When thinking about how to address the 4C Challenge for rail, the ability to innovate, both in technology and thought processes, is crucial. The four Cs challenge originated from the UK Railway Technical Strategy which defines the top-level strategic drivers as:
  • Cost
  • Customer
  • Carbon 
  • Capacity  

When combined, they ask the following question: How can we improve our customer experience whilst increasing capacity on the network and at the same time reducing both our carbon footprint and the cost of running the railway? 

The four Cs are inextricably linked: Won’t an increase in capacity mean an increase in the carbon footprint? Won’t more capacity mean a higher cost? Or, if we take cost out, will this negatively affect the passenger experience? This is where we need to think about the relationships across the four Cs and how we, as suppliers, can think holistically to benefit the complete picture.
 
An example is shown below where, starting with a clean sheet, a pantograph control solution has been developed for use without the need for an auxiliary compressor.
 
How to Innovate to Address the 4C Challenge for Rail - Parker Hannifin Pneumatic Division Europe
From an interiors perspective, this example illustrates our ability to have a direct impact on the four Cs, the four key top-level drivers, particularly when we employ innovative thinking. Not all projects or activities will be able to affect all four quite so obviously. They may have a significant impact in one area whilst still having a positive impact on another, but the thought process remains. 
 
If you look back at Fig. 1, we can see that two factors affect these four Cs, and they are weight and space. 

It is not just a case of reducing the size of something; performance characteristics must be at the very least retained but preferably enhanced whenever possible. You also have to consider mechanical strength, suitability for the operating environment and the forces that may be applied.
 
The reduction in size may also not result in a proportional weight loss, depending on the construction materials. Therefore, we should look at each point in isolation and then as a whole in order to achieve the ultimate end result.
  Weight

There are obviously many things that can affect component weight. Size, shape and material are all key, but production method can also be vital in producing the optimum form. 

Just consider the ability of additive manufacturing to produce components without traditional problems, such as shape and form restraints, or material waste produced by machining. The resulting components can be complex forms that maximise material thickness; this gives us engineered solutions that are both mechanically sound yet of lighter weight, and all in a shape or form to fit and integrate into the interfaces.  

  Space

Reducing equipment weight alone may not affect the space envelope required; however, some gains can usually be made. It is worth weighing up the cost of aiming for using less space against the cost of developing the equipment to fit.

How to Innovate to Address the 4C Challenge for Rail - Additive Manufacturing Example
Miniaturisation in itself can be an expensive exercise. It may be better to think of the effective utilisation of available space and look at methods to reduce wasted space. As previously stated, additive (or 3D) manufacturing can go some way towards addressing this, but the optimised design must include a consideration of access for maintenance and service requirements. 

However, the previously illustrated example shows: weight and space can also be reduced by returning to basics and challenging the current thinking.
 
The “we’ve always done it this way”, or “this is best practice”, “if it ain’t broke, don’t fix it” sayings need to be challenged; then maybe a new best practice will come to light. 
 
New technologies that benefit the whole life-performance and life-cycle costs can be considered, including the IoT (Internet of Things). Operating from this level we can also take a holistic view of the vehicle system with the four Cs in mind. The link, then, to innovation – which may not mean a completely new solution, but could include technology transfer from other industries and utilising alternative technologies – can truly be explored and the benefits maximised. 
 
It may also be that it's not a new technology that facilitates a new approach, it may be advancements in existing technologies that previously could not have met the requirements, so preconceptions need to be taken out of the thought process.
 
Learn more

Learn more about Parker solutions for rail at this transportation website, or contact our dedicated transportation team to discuss your particular rail application performance, cost, weight and space requirements.

 

How to Innovate to Address the 4C Challenge for Rail - Dave Walker, Market Development Manager for Rail - Parker Hannifin Pneumatic Division Europe

Article contributed by Dave Walker, market development manager for Rail, Motion Systems Group, Parker Hannifin Corporation. 

 

 

 

 

 

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Know Your Pneumatics: Specifying Cylinders for Size Restricted Spaces - Pharmaceutical Production Line - Parker Hannifin - Pneumatic Division EuropeFor applications with space limitations or size restrictions, integrating a standard linear actuator to achieve the required force / thrust can sometimes be a challenge. However, utilising specialist constructions of linear actuators, such as Tandem and Duplex cylinders can provide a solution.

Tandem cylinders

When designing for a pneumatic application, there are times when size restrictions can limit the space available for the installation of the required linear actuator. This can potentially limit the maximum force (thrust) available, as this is relative to the air pressure working on the piston area governed by the cylinder bore size. 

Know Your Pneumatics: Specifying Cylinders for Size Restricted Spaces - Parker Tandem Cylinder - Parker Hannifin - Pneumatic Division EuropeOne method to overcome this issue is to install a Tandem cylinder, as a smaller bore size can be used to generate a greater force ratio.

Tandem cylinders are 2 double acting cylinders, of the same bore size and stroke length, assembled in series to share a common piston rod. 

Air is provided to the ports of each cylinder and, because this acts on both pistons, they produce nearly double the force (thrust) of a single cylinder. 

This can be an advantage when space is restricted, as a smaller bore size can be used but does have the disadvantage of producing a longer cylinder relative to stroke length.

Duplex cylinders

 

Duplex arrangements provide intermediate positioning options that are not possible with a single pneumatic cylinder. When connected back to back as a single unit, Duplex cylinders can double the available force where space is limited.

Know Your Pneumatics: Specifying Cylinders for Size Restricted Spaces - Parker Duplex Cylinder - Parker Hannifin - Pneumatic Division EuropeTypically, a pneumatic rod type cylinder provides 2 static positions of operation – fully retracted and fully extended, with the distance being governed by the cylinder stroke length.

Being pneumatically operated means the cylinder cannot be stopped mid-stroke to a predetermined position. 

However, if required, pneumatic cylinders can achieve 3 or 4 positions. Duplex cylinders are constructed by using 2 double acting cylinders arranged back to back with separate piston rods, connected by common tie rods or a flange mounted back to back mounting.

Two cylinders installed back to back with the same stroke give a 3 position cylinder with a symmetrical centre position. Whereas different strokes give a 4 position cylinder where the two central positions can be calculated from different stroke lengths.

For a 4 position cylinder (cylinders with differing stroke lengths):

Position 1: Both cylinders A and B are in the retracted stroke positions.

Know Your Pneumatics: Specifying Cylinders for Size Restricted Spaces - Position 1 Duplex Cylinder - Parker Hannifin - Pneumatic Division Europe

Position 2: Cylinder A is in the extended stroke position and cylinder B remains in the retracted stroke position.

Know Your Pneumatics: Specifying Cylinders for Size Restricted Spaces - Position 1 Duplex Cylinder - Parker Hannifin - Pneumatic Division Europe

Position 3: Both cylinders A and B are in the extended stroke position.

Know Your Pneumatics: Specifying Cylinders for Size Restricted Spaces - Position 1 Duplex Cylinder - Parker Hannifin - Pneumatic Division Europe

Position 4: Cylinder A is in the retracted stroke position and cylinder B is in the extended stroke position. 

Know Your Pneumatics: Specifying Cylinders for Size Restricted Spaces - Position 1 Duplex Cylinder - Parker Hannifin - Pneumatic Division Europe

Learn more

The challenges for pneumatic cylinders are as numerous as the sectors in which they are needed to operate. Downtime costs money and lost production must be avoided for anything other than routine maintenance. Hence careful selection based on operating requirements and prevailing environmental factors must be given proper attention from the outset.

Compare features of Parker pneumatic cylinders to find the best one for your application environment. 

Know Your Pneumatics: Specifying Cylinders for Size Restricted Spaces - Kevin Hill - Parker Hannifin - Pneumatic Division EuropeArticle contributed by Kevin Hill, product manager for Actuators, Pneumatic Division Europe, Parker Hannifin Corporation.  



 

 

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5 Ways to Improve Air Flow and Reduce Operating Costs - Packaging Line - Parker Hannifin - Pneumatic Division EuropePneumatics technology is key to manufacturing processes as compressed air is utilised in everything from cooling to controlling automated machinery on assembly and packaging lines.
 
Since pneumatics make up a sizable proportion of a plant’s energy consumption, taking the steps to ensure wastage and leaks are minimised, whilst maximising airflow in the system can result in significant cost savings and better plant efficiency. 
 
1. Size your pneumatic components correctly
The old saying ‘pipe size is right size’ is no longer valid as many engineers have realised that large, pipe-sized components are no longer the best choice for running an efficient pneumatic system.
 
5 Ways to Improve Air Flow and Reduce Operating Costs - Parker P33F Particulate Filter - Parker Hannifin - Pneumatic Division EuropeFor example, a standard airline filter, such as Parker's P33F particulate filter, uses centrifugal action in the head to prevent water and other particles from contaminating the line.
 
If the filter is sized too large (according to the pipe size), then the centrifugal action will not be robust enough to remove the water. However, sizing it too small will result in a very noticeable pressure drop. 
 
Finding the exact size of a component for your application is critical for the overall efficiency of the system and will avoid these unnecessary pressure drops.
Another factor to consider is to check whether the piping itself is correctly sized.
 
2. Rethink the plumbing
In many pneumatic systems, the piping will run down from the main-line header into an application. 
 
5 Ways to Improve Air Flow and Reduce Operating Costs - Parker Thermoplastic Quick-Coupler Connector - Parker Hannifin - Pneumatic Division EuropeThis piping is often connected by a quick-coupler connector, which snaps together using a male and female piece. These connectors are essential if you need to couple and uncouple devices a lot. 
However, they tend to have high rates of pressure loss which can add to starving the system if it is already running at its maximum. 
 
As well as causing press loss, connectors can also become clogged up with the rust and scale flakes that can build up inside steel pipes. 
 
So, consider replacing steel plumbing with plastic, such as Parker's Thermoplastic solution or changing to standardised fittings and links made from aluminum instead of steel.
 
3. Adopt the dual pressure approach
Most applications are still using a single pressure circuit – with a single supply pressure and dual exhaust approach. This setup provides optimal exhaust conditions, but still may not always be the best and most efficient setup for many industrial applications.
 
An alternative technique is known as the dual pressure approach, best suited for applications where the same force is not required for the extend and retract conditions.
 
For example, a cylinder might need to be extended to move a load at 80 PSI, but the same force is not needed to reset the cylinder. Through the use of two regulators, the cylinder can be run at 80 out and 30 back in a dual pressure model to make the system more efficient. 
 
There are several ways to achieve those two pressures, and some are more efficient than others, but the basic principle of higher pressure out and lower pressure on retract remains the same in all cases.
 
4. Change filters
Another obvious way of optimising efficiency is to replace dirty elements. Typical commercial primary filters in a pneumatic circuit are designed to filter out particles as small as five microns from the air. Many of the filters commonly employ a spinning action to filter out any water droplets.
 
5 Ways to Improve Air Flow and Reduce Operating Costs - Parker P3LF Lite Particulate Filter - Parker Hannifin - Pneumatic Division EuropeInitially, the particulate filter might be sized for two or three pounds of pressure differential. This provides enough back pressure for the correct amount of airflow in and water filtered out. 
 
However, when contamination starts to coat not only the outside of the element but also the inner surfaces, part of the orifice is bound to get closed up, effectively dropping the three-pound differential steadily. Finally, it might get to the point where five to 10 PSI is lost simply because the element is dirty.
 
A lot of users will try to take the element out and give it a clean to get the system back in service. This is not a good idea because a lot of the contaminants are on the inside and simply can’t be reached. 
 
Instead of simply replacing the relatively inexpensive part, they are running the system on a clogged filter that costs more to run every month because the compressor is labouring to make up the extra pressure drop.
 
One of the main reasons Parker moved from a sintered bronze or fibre paper type of filter to a white sintered plastic element, as featured on the Parker P3L Lite Particulate Filter, was to give a clear visual indication that when they look dirty, they should be replaced.
 
5. Clean, dry air
One of the main principles of compressing air is to take the surrounding air and jamming it into a small container, but this air also brings with it a multitude of water, dirt and everything else that’s in the environment around the compressor. 
 
When you compress air, you also heat it up, and the act of compression is part of the gas loss. This results in the air wanting to hold on to that water until it cools off again. 
 
5 Ways to Improve Air Flow and Reduce Operating Costs - Parker P3TJ Dry Air System - Parker Hannifin - Pneumatic Division Europe
As the air cools off, water condenses in the system’s pipes, which is where water comes from inside the system. There are many different mechanisms that reduce the amount of water going downstream into the pneumatic system, but one of the main starting points would be a dryer, which will cool the air and allow the water to condense and fall out of it. 
 
Putting a dryer into the system, such as Parker's P3TJ Dry Air System, won’t eliminate all of the water in it, but it will remove the bulk of it. Particulate filters then come into play at the point of use to clear out the remainder of water and dust in the system. 
 
Simply living with water in the system as a fact of life creates a lot of problems with equipment rusting and other environmental issues. 
 
All of these points have to be considered in order to optimise energy conservation and boosting air flow. It’s also important to remember that as plants scale up, so does every part of the pneumatic system need to be upscaled to cope with the demand.
 

Learn more

Parker offers a large selection of dryers, filters, lubricators, regulators and combination units. Full-featured filters, regulators, filter/regulators, and lubricators are available with a wide range of standard options to meet your air preparation needs. Our clean air systems make it easy for companies to protect equipment, reduce downtime and maintenance costs and maximize compressed air solutions.
 

5 Ways to Improve Air Flow and Reduce Operating Costs - Hermann Stoerk Product Manager for Air Preparation - Parker Hannifin - Pneumatic Division EuropeArticle contributed by Hermann Storck, product manager for air preparation, Pneumatic Division Europe, Parker Hannifin Corporation.

 

 

 

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5 Ways to Improve Air Flow and Reduce Operating Costs - Packaging Line - Parker Hannifin - Pneumatic Division EuropePneumatics technology is key to manufacturing processes as compressed air is utilised in everything from cooling to controlling automated machinery on assembly and packaging lines.
 
Since pneumatics make up a sizable proportion of a plant’s energy consumption, taking the steps to ensure wastage and leaks are minimised, whilst maximising air flow in the system, can result in significant cost savings and better plant efficiency. 
 
1. Size your pneumatic components correctly
The old saying ‘pipe size is right size’ is no longer valid as many engineers have realised that large, pipe-sized components are no longer the best choice for running an efficient pneumatic system.
 
5 Ways to Improve Air Flow and Reduce Operating Costs - Parker P33F Particulate Filter - Parker Hannifin - Pneumatic Division EuropeFor example, a standard air line filter, such as Parker's P33F particulate filter, uses centrifugal action in the head to prevent water and other particles from contaminating the line.
 
If the filter is sized too large (according to the pipe size), then the centrifugal action will not be robust enough to remove the water. However, sizing it too small will result in a very noticeable pressure drop. 
 
Finding the exact size of component for your application is critical for the overall efficiency of the system and will avoid these unnecessary pressure drops.
Another factor to consider is to check whether the piping itself is correctly sized.
 
2. Rethink the plumbing
In many pneumatic systems, the piping will run down from the main-line header into an application. 
 
5 Ways to Improve Air Flow and Reduce Operating Costs - Parker Thermoplastic Quick-Coupler Connector - Parker Hannifin - Pneumatic Division EuropeThis piping is often connected by a quick-coupler connector, which snaps together using a male and female piece. These connectors are essential if you need to couple and uncouple devices a lot. 
However, they tend to have high rates of pressure loss which can add to starving the system if it is already running at its maximum. 
 
As well as causing press loss, connectors can also become clogged up with the rust and scale flakes that can build up inside steel pipes. 
 
So, consider replacing steel plumbing with plastic, such as Parker's Thermoplastic solution or changing to standardised fittings and links made from aluminium instead of steel.
 
3. Adopt the dual pressure approach
Most applications are still using a single pressure circuit – with a single supply pressure and dual exhaust approach. This setup provides optimal exhaust conditions, but still may not always be the best and most efficient setup for many industrial applications.
 
An alternative technique is known as the dual pressure approach, best suited for applications where the same force is not required for the extend and retract conditions.
 
For example, a cylinder might need to be extended to move a load at 80 PSI, but the same force is not needed to reset the cylinder. Through the use of two regulators, the cylinder can be run at 80 out and 30 back in a dual pressure model to make the system more efficient. 
 
There are several ways to achieve those two pressures, and some are more efficient than others, but the basic principle of higher pressure out and lower pressure on retract remains the same in all cases.
 
4. Change filters
Another obvious way of optimising efficiency is to replace dirty elements. Typical commercial primary filters in a pneumatic circuit are designed to filter out particles as small as five microns from the air. Many of the filters commonly employ a spinning action to filter out any water droplets.
 
5 Ways to Improve Air Flow and Reduce Operating Costs - Parker P3LF Lite Particulate Filter - Parker Hannifin - Pneumatic Division EuropeInitially the particulate filter might be sized for two or three pounds of pressure differential. This provides enough back pressure for the correct amount of air flow in and water filtered out. 
 
However, when contamination starts to coat not only the outside of the element but also the inner surfaces, part of the orifice is bound to get closed up, effectively dropping the three-pound differential steadily. Finally, it might get to the point where five to 10 PSI is lost simply because the element is dirty.
 
A lot of users will try to take the element out and give it a clean to get the system back in service. This is not a good idea because a lot of the contaminants are on the inside and simply can’t be reached. 
 
Instead of simply replacing the relatively inexpensive part, they are running the system on a clogged filter that costs more to run every month because the compressor is labouring to make up the extra pressure drop.
 
One of the main reasons Parker moved from a sintered bronze or fibre paper type of filter to a white sintered plastic element, as featured on the Parker P3L Lite Particulate Filter, was to give a clear visual indication that when they look dirty, they should be replaced.
 
5. Clean, dry air
One of the main principles of compressing air is to take the surrounding air and jamming it into a small container, but this air also brings with it a multitude of water, dirt and everything else that’s in the environment around the compressor. 
 
When you compress air, you also heat it up, and the act of compression is part of the gas loss. This results in the air wanting to hold on to that water until it cools off again. 
 
5 Ways to Improve Air Flow and Reduce Operating Costs - Parker P3TJ Dry Air System - Parker Hannifin - Pneumatic Division Europe
As the air cools off, water condenses in the system’s pipes, which is where water comes from inside the system. There are many different mechanisms that reduce the amount of water going downstream into the pneumatic system, but one of the main starting points would be a dryer, which will cool the air and allow the water to condense and fall out of it. 
 
Putting a dryer into the system, such as Parker's P3TJ Dry Air System, won’t eliminate all of the water in it, but it will remove the bulk of it. Particulate filters then come into play at the point of use to clear out the remainder of water and dust in the system. 
 
Simply living with water in the system as a fact of life creates a lot of problems with equipment rusting and other environmental issues. 
 
All of these points have to be considered in order to optimise energy conservation and boosting air flow. It’s also important to remember that as plants scale up, so does every part of the pneumatic system need to be upscaled to cope with the demand.
 

Learn more

Parker offers a large selection of dryers, filters, lubricators, regulators and combination units. Full featured filters, regulators, filter/regulators and lubricators are available with a wide range of standard options to meet your air preparation needs. Our clean air systems make it easy for companies to protect equipment, reduce downtime and maintenance costs and maximize compressed air solutions.
 

5 Ways to Improve Air Flow and Reduce Operating Costs - Hermann Stoerk Product Manager for Air Preparation - Parker Hannifin - Pneumatic Division EuropeArticle contributed by Hermann Storck, product manager for air preparation, Pneumatic Division Europe, Parker Hannifin Corporation.

 

 

 

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Know Your Pneumatics: Basics of Air Preparation - Factory Environment - Parker Hannifin - Pneumatic Division EuropeHaving a steady supply of clean and dry air is a requirement for protecting pneumatic components and ensuring their proper operation.

For applications such as clamping, positioning, pushing and lifting, having good quality air flow for the required pressure is essential and must be designed into the system.

Compressed air often flows from the plant to the machine, passing through multiple devices, pipes and fittings along the way, that can add particulates, oil and moisture. 

Preparing the air before it is used will help to ensure your machine gets the best possible protection and a better possible service life. 

 

Filters

Compressed air filters should receive the supply air first and are necessary to reduce contaminates and moisture in the compressed air at the machine. 

Know Your Pneumatics: Basics of Air Preparation - Parker 14F Miniature Particulate Filter - Parker Hannifin - Pneumatic Division EuropeThey are available in different sizes depending on the needs of your application, standard filters remove particulates around 40 µm while fine filters are available to remove particulates down to 5 µm or less, such as Parker's 14F miniature particulate filter.

Process instrumentation or high-speed pneumatic tools will require a finer particle filtration, along with food and pharmaceutical applications. 

Filters require preventative maintenance to ensure they maintain optimum efficiency and filter effectively. The key area of maintenance for filters is taking care of the filter-bowl.

All the collected pollutants from the air will fill the bowl so you need to control the level either with a manul drain, a semi-automatic drain or ideally with an automatic drain. Also, the filter element should be controlled from time to time, for Coalescing Filters a PDI (pressure drop indicator) is used to see the rate of contamination.



Regulators

After the air has been through the filter, a pressure regulator will take that clean, dry air and control the pressure downstream.

Know Your Pneumatics: Basics of Air Preparation - P33R Standard Pressure Regulator - Parker Hannifin - Pneumatic Division Europe

They are operated by turning a valve to determine the pressure – turning it clockwise will allow greater pressure to pass. 

Air preparation best practice dictates that a regulator should only be used to regulate downstream pressure. For on/off functionality, or to control the flow of air into your system, a single on/off valve are recommended.

Combination filter regulator units have all the capabilities of the separate filters and regulators combined into a single unit. This design will save significant pneumatic panel space and also save on cost.

 

Lubricators

A lubricator should be added to a system to provide downstream pneumatic components with a constant supply of oil lubrication by introducing a small amount of oil to the compressed air stream. 

Know Your Pneumatics: Basics of Air Preparation - P33L Standard Mist Lubricator - Parker Hannifin - Pneumatic Division Europe

The oil will be dissolved and transported by the airstream to the point of use, in the form of fog. This technology is important to guarantee the best lubrication of your components, keeping your machine operating at maximum efficiency.
  
Lubricators are available in a variety of port sizes to match other air preparation components. They often use an adjustable visual indicator to measure the amount of oil downstream and have an oil reservoir bowl that can be monitored to ensure a constant supply. The bowls are also available in several sizes to store more oil as needed. 

Today’s pneumatic devices sometimes don’t require lubrication but high-speed pneumatic power tools often do. Some are pre-lubricated and don’t require it. 

 

Air preparation systems

Know Your Pneumatics: Basics of Air Preparation - P33 Standard FRL System - Parker Hannifin - Pneumatic Division EuropeA typical air preparation system includes filters, regulators and lubricators (sometimes called FRL systems).

These solutions can be specified as a configured 3-piece unit designed to deliver accurate pressure regulation, high moisture removal efficiency and proportional oil delivery over a wide range of air flows. Combination units save significant pneumatic panel space and also help to save costs.

Proper design, correct specification and regular monitoring of bowl, filter element and oil in the lubricator will lead to an air preparation system that will ensure many years of trouble free operation for downstream pneumatic components.  
 
 
Learn more

Choose from a range of high performance and efficient Parker Air Preparation products for your application needs. Parker offers a large selection of dryers, filters, lubricators, regulators and combination units, available with a wide range of standard options to meet your air preparation needs.

Know Your Pneumatics: Basics of Air Preparation - Hermann Stoerk - Parker Hannifin - Pneumatic Division EuropeArticle contributed by Hermann Stoerk, product manager air preparation, Pneumatic Division Europe, Parker Hannifin Corporation.




 

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Know Your Pneumatics: Single or Double Acting? Choosing the Right Cylinder - Bus Doors Opening - Parker Hannifin - Pneumatic Division EuropeThe most popular style of pneumatic actuator consists of a piston and rod moving inside a closed cylinder, designed to move in a straight line to deliver linear motion. This style of linear actuator is utilized in a variety of industrial sectors, factory automation and packaging, plus transportation and life science applications.

When looking to specify linear actuators there are two types of operating principle: single acting and double acting. We will explore these variations, typical applications plus advantages and disadvantages.

  Single acting cylinders

A single acting cylinder is one where the thrust or output force is developed in only one direction. 

The piston is returned by a fitted spring, or by some other external means such as a weight, mechanical movement, gravity or an external spring. They have a single port to allow compressed air to enter the cylinder to move the piston to the desired position.

There are two types of single acting cylinder:

  • ‘Push’ type – where the application of air pressure produces a thrust, thus ‘pushing’ the piston

Know Your Pneumatics: Single or Double Acting? Choosing the Right Cylinder - Single Acting Cylinder Push Type - Parker Hannifin - Pneumatic Division Europe

  • ‘Pull’ type – where the application of air pressure produces a thrust, thus ‘pulling’ the piston

Know Your Pneumatics: Do I need a single or double acting cylinder? - Single Acting Cylinder - Push Type - Parker Hannifin - Pneumatic Division Europe

Know Your Pneumatics: Single or Double Acting? Choosing the Right Cylinder - P1P Single Acting Cylinder - Parker Hannifin - Pneumatic Division Europe

Single acting cylinders, such as Parker's P1P Series, are typically used for applications where work is done only in one direction, such as clamping, positioning, marking, stroking and light assembly operations.

Advantages:

  • Simple design
  • Compact size
  • Reduction in valve and piping costs
  • Air consumption is halved compared with the equivalent sized double acting cylinder

Disadvantages:

  • Return spring side of the cylinder is vented to atmosphere – may allow the ingress of foreign matter, which may lead to malfunctioning and reducing the life of the cylinder
  • Spring operation with extended cylinder life can become inconsistent and provide uncertain end of stroke positions
  • Bore size and stroke of the cylinder is restricted due to limitations of the spring size and force
  • Slight reduction of thrust due to the opposing spring force

 

Double acting cylinders

A double acting pneumatic cylinder is one where the thrust, or output force, is developed in both extending and retracting directions. Double acting cylinders have a port at each end and move the piston forward and back by alternating the port that receives the high-pressure air, necessary when a load must be moved in both directions such as opening and closing a gate.

Air pressure is applied alternatively to the opposite ends of the piston. Application of air pressure produces a thrust in the positive (push) stroke, and a thrust in the negative (pull) stroke.
Know Your Pneumatics: Single or Double Acting? Choosing the Right Cylinder - Double Acting Cylinder - Parker Hannifin - Pneumatic Division Europe
Double acting cylinders are typically used in all applications where the thrusts and stroke lengths required are in excess of those available from single acting cylinders. Small double acting cylinders are also used for applications where positive end-of-stroke positions are required for both strokes.

Know Your Pneumatics: Single or Double Acting? Choosing the Right Cylinder - P1D Double Acting Cylinder - Parker Hannifin - Pneumatic Division EuropeDouble acting cylinders, such as Parker's P1D Series, are the most widely used of all designs of linear actuators. They account for approximately 95% of all cylinders used in pneumatic control circuits.

Advantages:

  • Generally, ISO standards are based on the design of double acting cylinders
  • More extensive range of double acting cylinders than for single acting cylinders, giving many more options of bore and stroke sizes
  • Many variations on the basic double acting cylinder design

Disadvantages:

  • Cannot be simply held in a mid-position
  • Air is a compressible medium – if a pneumatic cylinder is to be used as a feed cylinder, it has to be coupled to a hydraulic slave cylinder to give a constant feed
  • Long stroke cylinders need adequate guiding of the piston rod

 

Learn more

Discover the 6 steps to specifying linear actuators in our blog Know Your Pneumatics: Specifying Linear Actuators.

 

Know Your Pneumatics: Single Acting vs Double Acting Cylinders - Kevin Hill, European Product Manager Pneumatic Actuators - Parker Hannifin - Pneumatic Division EuropeArticle contributed by Kevin Hill, European product manager pneumatic actuators, Pneumatic Division Europe, Parker Hannifin Corporation.

 

 

 

 

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