The Three Types of Pneumatic Cylinders

Several main types of pneumatic cylinders are available on the UK market today. For most industrial applications, it’s typically a straight choice between single-acting or double-acting pneumatic cylinders, with stainless steel cylinders adding a corrosion-resistant alternative. So what are the benefits of each? API UK explains all in this handy guide. 

WHAT IS A PNEUMATIC CYLINDER?

Pneumatic cylinders come in various shapes and sizes. Still, all operate on the same basic principle: they convert the power of compressed air into mechanical energy, usually in the form of linear or rotary motion. 

Pneumatic cylinders are classified according to the direction in which they work. Single-acting pneumatic cylinders extend and retract in only one direction, relying on a mechanical spring for the return movement. Whereas double-acting pneumatic cylinders can extend and retract in both directions.

Pneumatic cylinders are typically the final piece of the jigsaw within a pneumatic system, serving as the actuator. Therefore, selecting the correct type of pneumatic cylinder will greatly impact your application’s success, performance and productivity. 

TYPES OF PNEUMATIC CYLINDERS

Generally, there are two main types of pneumatic cylinders: single-acting and double-acting. API UK is one of the few manufacturers to manufacture and supply a range of stainless steel pneumatic cylinders specifically for hygienic and heavy-duty applications. Therefore, we think of our stainless steel cylinders as the third type of cylinder we can offer. Let’s take a look at their merits one by one.

SINGLE-ACTING PNEUMATIC CYLINDERS

There are two main types of single-acting pneumatic cylinders: push and pull. Clean, compressed air enters the single port in one direction, extending the piston (push) or causing it to retract (pull). When the compressed air is expelled through the same entry port, the mechanical spring returns the piston to its original ‘base’ position. This makes single-acting cylinders ideal for fail-safe applications requiring the piston to be in a certain position should air loss occur. 

Single-acting pneumatic cylinders typically boast a simple, low-cost design that makes for a simple installation with fewer valve and piping costs than double-acting cylinders. However, it’s worth bearing in mind that the opposing spring force means that single-acting pneumatic cylinders don’t deliver consistent output force throughout the entire piston stroke length (which is also limited for the same reason).

If you’re looking for reliable and durable single-acting pneumatic cylinders, look no further than our non-magnetic MS series and MSM series pneumatic cylinders. Both conform to ISO 6432 standards and deliver operating pressures of between 1-10 bar and temperature ratings of -20°C to +80°C. Constructed with polyurethane piston rod seals for low friction and long service life, both cylinder models can be provided as ATEX versions on request. 

DOUBLE-ACTING PNEUMATIC CYLINDERS

Double-acting pneumatic cylinders extend to a positive position and retract to a negative position. Compressed air enters the cap-end port, pushing the piston forward and forcing air out of the rod-end port. This causes the piston rod to extend (push/positive). The reverse action initiates the retraction (pull/negative), with air entering the rod-end port forcing the expulsion of air through the cap-end port and retracting the piston.

Their double-acting design means that double-acting pneumatic cylinders provide more precise and faster retraction control, a longer stroke and consistent output force. Additionally, they’re less likely to experience stalling, so operators can use them in a wider range of environments. Double-acting pneumatic cylinders also deliver smoother operation, are more efficient, and offer a wider range of stroke and bore sizes.

We have an extensive range of double-acting pneumatic cylinders here at API UK. For instance, our AMAK series is an ISO 15552 cushioned, magnetic pneumatic cylinder that features die-cast aluminium end caps, an anodised aluminium barrel, and three reed switch mounting options. Or, our CRT series of cylinder with a carbon steel rack and pinion is magnetic as standard and operates within a pressure range of 1.3 to 7 bar and temperatures between -10°C to +60°C.

STAINLESS STEEL PNEUMATIC CYLINDERS

As we mentioned earlier, API UK is one of the few manufacturers of high-quality stainless steel pneumatic cylinders. Stainless steel provides superior corrosion resistance, strength, durability, hygiene, and temperature resistance. For those reasons, stainless steel cylinders are perfect wherever strict sanitary requirements and frequent washdowns are required, such as food and beverage applications. Or in challenging operational environments that expose the cylinder to aggressive media, such as the chemical and oil and gas sectors.

Our stainless steel pneumatic cylinder range consists exclusively of double-acting cylinders. The ISO 15552 conforming AMX Series and ISO 6432 conforming MDMX Series are constructed from high-grade 316L stainless steel with a polyurethane piston rod seal for low friction and extended service life. Meanwhile, the ISO 6432 conforming MDX Series offers comparable performance, except with AISI 316 stainless steel end caps and piston rod, and a barrel made from AISI 304 stainless steel.

UK PNEUMATIC CYLINDER SUPPLIERS

As we’ve seen, several types of pneumatic cylinders are available on the market today, including hard-wearing and hygienic stainless steel varieties. Which you choose will very much depend on your needs. Single-acting cylinders are ideal for light assembly work but may need to be maintained or replaced more regularly despite their cheaper price tag. Double-acting cylinders are the preferred choice wherever greater speed, force and efficiency are required. If you’re not sure, our experts will be happy to help.

If you need a pneumatic cylinder in the UK, make API UK your first port of call. To discuss your pneumatic cylinder requirements or arrange a free on-site visit, speak with our technical team today. As expert pneumatic cylinder manufacturers, we can help you understand the options available and guide you towards the best system solution for your application. So call us today on 01782 206 995, email [email protected], or complete our contact form.