Bonfiglioli technology helps drive refurbishment of Sydney Harbour Bridge

The iconic Sydney Harbour Bridge, which was opened in 1932, is one of Australia’s most well known and photographed landmarks, along with the Sydney Opera House. The bridge is the world’s largest steel arch bridge with a total length of 2.3 km, the top of the bridge standing 134 metres above the harbour.

During the bridge’s 75th anniversary last year, the NSW Minister for Roads, Eric Roozendaal, announced structural and strengthening upgrades costing $8five million to maintain its good condition and to extend its lifespan. “We want to be celebrating the bridge on its 100th and 200th anniversaries. This work is designed to guarantee that,” said Roozendaal.

Essential to the upgrade are two 60-tonne workmen’s gantries, which are driven by synchronised sets of Bonfiglioli industrial gearboxes.

The A series bevel helical gearboxes — the same type used in manufacturing, mining, materials handling and primary processing applications — are used in sets of eight on each mobile platform to drive them along rails beneath the length of the 503 m long main arch of the bridge.

Supplied by the prominent Australian industrial crane manufacturer Eilbeck Cranes, the platforms feature encoders to ensure smooth synchronous operation of their A60 series Bonfiglioli gearmotors which, with 2.2 kW installed motor power and 2117 Nm output torque, drive four sets of wheels on each side of each platform. The compact drives also feature stainless steel brake components specially fitted to the brakemotors to ensure reliability of operation in marine environments and therefore ensure longevity of service on the bridge.

The managing director of Bonfiglioli Transmission (Aust and NZ) Pty Ltd, Malcolm Lewis, says the bridge represents one of Australia’s biggest industrial and structural maintenance tasks, involving more steel (55,000 t than was used to build the ocean liner Titanic. Painting alone required a total of 270,000 L for the first three protective coats and the job has continued in a neverending sequence, from end to end, ever since. The current refurbishment program, scheduled for completion next year, includes the two new gantries for which the Bonfiglioli drives were chosen.

“This a project of national importance, so it was a considerable distinction to have our drives chosen by Eilbeck Cranes to provide the high standards of performance and reliability required,” he said.

The Bonfiglioli A series drives used on the gantries feature finite element analysis procedures used in their design and construction. This allows for lightweight construction while maintaining strength and durability with case-hardened nickel chrome steel gears. Lewis added that major features of the A series include high torque, high efficiency and low noise. Operating efficiencies are enhanced by Bonfiglioli’s high-performance hypoid bevel gear pair, which gives significant energy savings. Low-noise gearing is achieved by locating the bevel gear pair at the output stage of the gearmotor. This allows noise reductions significantly below similarly sized traditional bevel helical gearmotors and allows the A series to conform to the most arduous of mechanical specifications.

The A series’ wide ratio range (with up to four reduction stages in the larger units) permits one A series to be used where previously two gear units increased dimensions and cost. The A series is also available with compact motors, to further reduce overall dimensions and increase cost effectiveness.

Bonfiglioli Transmission Pty Ltd
www.bonfiglioli.com.au
Saeco Bearings & Transmission
www.saeco.co.nz