Slewing rings from igus help add lively component to three-metre owls

Profile

• What was needed: PRT slewing ring
• Requirements: the slewing rings had to be wide enough for mechanical cables, components and lighting elements to passed through them. They also had to withstand high axial and dynamic loads, and be maintenance-free despite the weather.
• Success for the customer: the PRT slewing ring bearings from igus are resistant to chemicals, vibration-dampening and have low moisture absorption. They are also very robust and can withstand heavy loads.

A lubrication-free and maintenance-free slewing ring bearing ensures the reliable movement of the head even in the most diverse weather conditions. (Source: igus GmbH)

Problem

The challenge was finding a slewing ring bearing that could meet all the requirements needed for this application. New American Public Art has used igus in past projects, and worked with the company’s United States team in Providence, R.I., to find the best slewing ring for the large owls. "For this bearing, we needed a very specific set of qualities," he said. It had to be very wide to allow for mechanical and lighting elements to pass through it. This bearing needed to support a large axial and dynamic range to pose no hazard to the public, and be as maintenance-free as possible despite various weather conditions. This demanding list of qualities ruled out 90% of bearings on the market."

Solution

The sliding surface of the igus slewing rings is made of the high-performance polymer iglidur J, which is characterised by good chemical resistance, vibration dampening and low moisture absorption. The ring has an axial static load of 27,000 newtons and an axial dynamic load of 7,000 newtons. Thanks to the large PRT outer diameter of 450 millimetres, the sculpture requires less supporting material. The large inner diameter (430 millimetres) allows us to pass through fibre-optic cables, which light up the owls’ eyes at night,’’ Sternof Beyer explained. "The axial and dynamic ranges are more than enough for the weight of the owl head, but also give us assurance if the public decides to climb onto the owl or pull its head."

Products used