Pneumatic drives, cylinders or actuators are what provides motion and force to automated pneumatic systems and processes. Pneumatic drives work by forcing compressed air into the cylinder, which causes a moving part (usually a piston rod) inside it to create linear or rotary motion. Some sort of mechanism is then attached to the piston, which converts its energy for a practical application, such as moving, clamping or positioning tools in an automated system.
Pneumatic drives are simple, require little maintenance, and are a clean and cost-effective way to produce energy. They're also easy to install, durable, and can achieve high cycle speeds without overheating. Pneumatic drives generate accurate rotary or linear motion at a wide variety of speeds, and don't cause internal damage if they stall. Pneumatic cylinders can function in environments with high humidity and extreme temperatures, and in dirty or dusty conditions.
At Rowse Pneumatics we have many years of experience with pneumatic drives and cylinders. We've seen many new developments and innovations, from the simplest one-stroke piston to the most complex linear slides and rotary indexing tables. Pneumatic cylinders and drives are one of the simplest ways to create force and motion and their popularity has increased as they have become increasingly versatile.
We stock a vast range of pneumatic cylinders and drives at Rowse Pneumatics, which are generally categorised into the following core types:
Pneumatic cylinders with guides can prevent the piston rotating by means of blocks or rods. This provides controlled linear motion, and reduces any bending of the piston/rod and uneven wear on the seals. They tend to be used in applications with high side or offset loads, or where loads need specific guiding, such as on a conveyor. Pneumatic cylinders with guide rods and plain bearings are more resistant to lateral forces, while those that employ recirculating ball bearings are better for heavy torque loads.
Pneumatic cylinders with piston rods are available in two main types: single-acting or double-acting. If it has only one air input port, the drive force is transmitted in only one direction, so it's single-acting, and the piston rod needs a spring to push it back to its original position. A double-acting pneumatic cylinder has two air intake ports, so the piston rod is moved in both directions (instroke/outstroke). This allows a greater stroke length, but has a greater potential for bending or buckling.
A combination of single and double-acting pneumatic cylinders can be engineered to form a third type of drive, the pneumatic telescopic cylinder. These can achieve a noticeably longer stroke, but at the expense of less rigidity, so their load-bearing capacity is also much lower.
ISO cylinders are pneumatic cylinders that conform to certain standards, set by the International Standards Organisation (ISO). The main standards applicable to pneumatic drives are ISO 6431/6432, ISO 15552 and ISO 21287, which stipulate the dimensions for the drive, its detachable mountings and its accessories.
ISO 6431:1992 governs single rod cylinders with bore sizes from 32mm-320mm, while ISO 6432 covers bore sizes from 8.25mm. ISO 15552:2018 governs single or double-acting pneumatic cylinders, and ISO 21287:2004 generally applies to compact cylinders with bores ranging from 20mm-100mm.
Pneumatic stopper cylinders are used when a load or equipment needs to be stopped with the minimum of impact. They are frequently used for conveyor belt activities, and offer flexible and rebound-free stop/start blocking. Pneumatic stopper cylinders come with piston rods, levers and rollers, and can be installed either horizontally or vertically. Some types use magnetic sensors which work with signals from a control unit, and proximity or position switches provide a controlled stop and restart.
Rotary pneumatic cylinders essentially convert the cylinder’s piston rod action into rotary motion, by means of a vane or rack-and-pinion mechanism. Like other pneumatic cylinders, they are simple, durable, can sustain challenging or hazardous conditions and offer a high size to force ratio. Rotary motion can be achieved in a standard pneumatic cylinder with a pivot arm, but rotary drives are simpler, self-contained units, with their own internal bearing sets to support the load.