News Releases

December 2010

Air Spring actuation cuts out a weakest link to give safe and reliable lift and tilt table operation

Scissor lifts and tilt tables make many assembly, construction, fabrication and maintenance tasks easier and safer.

They are particularly useful when users need to lift and then work at different heights and angles with heavy materials involved in mechanical and building maintenance and fabrication, distribution and warehousing, industrial and construction tasks.

Pneumatically actuated scissor lifts and tilt tables offer reliable and safe performance: if the power cuts out or the system falters, then the actuator will still compress gently with the air (or water) inside offering resistance. Scissor lifts and tilt tables actuated by Air Springs Airstroke(R) actuators also eliminate one of the weakest links in pneumatic actuation: the seals in traditional cylinders used to actuate the equipment involved.

This advantage is especially critical in aggressive atmospheres laden with dust and waste, where such cylinders can clog up and wear prematurely over the millions of cycles for which they must operate, says pneumatic actuation and isolation specialist Simon Agar. Mr Agar – who is General Manager of Air Springs Supply Pty Ltd – has more than 20 years experience with Firestone air spring actuators known as Airstrokes^®.

He says Airstrokes are, in essence, heavy-duty balloons. While Airstrokes are available in a variety of styles, sporting differing components that control the shape and path of axial extension (including single, double and triple convoluted, as well as rolling sleeve), their basic design is the same.

"These highly engineered rubber and fabric balloons or air bags are flexible-wall, bellows-type air cylinders which are ideally suited to engineering of assemblies for high-repetition, high reliability tasks, for which they are inflated and deflated to achieve their purpose. Traditional cylinder designs contain a piston sliding within a housing of circular cross-section connected to the work by a rod passing through one end of the device. This design necessitates several guides and seals, which align and seal the sliding surfaces. These allow a pressurised, contained column of fluid to apply force to the piston. (See illustration below).

"An air spring uses none of these components to contain and channel its column of fluid.

An air spring contains its column of air in a fabric-reinforced rubber envelope, or bellows. The ends are sealed by bead plates, which are crimped around the bead of the bellows. These plates contain the attachment hardware for the part, normally a blind tapped hole called a blind nut. An air fitting, generally in one bead plate, allows fluid (air) to be introduced into the chamber. The fabric in the side wall of the bellows restricts radial expansion, so pressure is built up, causing axial extension to provide the scissor lift or tilt function required."

Air Springs also offer side load flexibility and simplified attachment. 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.

A broad range of air springs is available to Australian industry. Airstroke actuators from Air Springs Supply, for example, give 40-40,000kg of pushing or lifting power. Offering power strokes of up to 350mm, Airstrokes are actuated by standard factory, workshop or warehouse compressed air systems or by basic compressor equipment found on nearly every industrial or construction worksite.

Conventional pneumatic cylinder (left) v Airstroke^® (right).

Free technical information

Would you like to learn more about the technology discussed here? Readers can receive more information by contacting Air Springs Supply Pty Ltd, PO Box 215 West Ryde, 2114, ph (02) 9807 4077, fax (02) 9807 6979.

For more information about Air Springs Supply's national distribution and technical support network, please contact Air Springs Supply Pty Ltd, 10 Angas St, Meadowbank, Sydney 2114, ph (02) 9807 4077, fax (02) 9807 6979, sales@airsprings.com.au

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