Actuation solves off-centre loading

Side loads are one of the big killers of conventional hydraulic and pneumatic cylinders used in materials handling applications.

Even as little as a degree or two of off-centre loading can spell doom for the rods, seals or bores of common types of actuators used for lifting and placing objects or providing constant loads on conveying belts or materials webs. Bent rods, scored bores or damaged seals can lead to down time on such essential apparatus in industries like bulk materials handling.

A robust alternative is provided by Firestone Airstroke actuators. These tough, flexible wall bellows contain no internal moving parts to break or bend, cause internal scoring or require lubrication. Because an air spring has a flexible, compliant bellows wall, instead of seals or guides, the bellows follows the path of least resistance. This means users don't have to worry about side loads caused by misalignment. Unlike a conventional cylinder (which extends a rod, or plunger, to provide actuation) Airstrokes themselves inflate to provide actuation force.

Using standard factory compressed air at 7 bar - or other compatible gases and liquids such as nitrogen and water-glycol solutions - Airstrokes inflate like enormously robust tubular balloons, extending to deliver actuating forces between 40-40,000 kg a unit.

Airstrokes can also cycle rapidly - the lack of seals also means lack of friction - which makes them suitable for conveying or stamping tasks.

Airstrokes also possess the capability of stroking through an arc without a clevis. Angular motion of up to 30° is possible, along with the design advantage of generally less complex linkages.

Airstroke sizes are available from about 31 to 940 mm diameter. These offer compact starting heights of 30.48 and 139.7 mm respectively (with the tiny new plastic moulded Airomatic polyactuator - a different design - having a starting height of just 16 mm).

The smaller sizes provide a wide range of forces required for conveyor and processing operations, while the largest sizes allow force up to 40,000 kg each using only 7 bar (100 psi) air pressure.