Busak+Shamban advanced sealing technology was incorporated intothe Enerpac hydraulic systems, used to push road decks across theworld’s highest bridge.
The bridge, inaugurated on the 14th December 2004 by Presidentof France, Jacques Chirac, carries traffic on the new E11 Paris toBarcelona autoroute. It has the tallest bridge piers everconstructed at 240 metres and its overall height of 336.4 metresmakes it the highest bridge in the world.
Advanced hydraulic technology, provided by Enerpac (specialistsin construction hydraulics), was needed to push the 27.35 metrewide decks of this new six-lane highway, across the Millau Viaductin Southern France, onto its concrete piers.
Hydraulic launching devices were used to lift, and then push thedecks into place, each system incorporating a cylinder with liftingcapability of 250 tonnes. Manufactured by Enerpac, cylindercapacities were varied to suit force requirements, the mostpowerful up to 14.4 tonnes, with 24 (600 tonne) support cylinders.A total of 388 cylinders were used, each fitted with Busak+Shambansealing systems, designed to withstand the massive demands of theapplication and operating pressures up to 700 bar. Leak-freesealing and resistance to ingress from abrasive materials wereessential to achieve optimum hydraulic system performance.
Development engineers from Busak+Shamban (Spain) worked withEnerpac’s Construction Centre of Excellence in Madrid, to designsystems incorporating combinations of between four and 14 sealingelements, to suit bore diameters of 145mm to 305mm and roddiameters of 70mm to 220mm. Dependent on the cylinder’srequirements, these included Turcon® Glydring®, Stepseal® andExcluder®, Zurcon® Rimseal® and Luytex® Slydring®.
Busak+Shamban proprietary Turcon® material was selected for themajority of the seals within the system. This specialisthigh-performance, engineered thermoplastic, has the characteristicsof very low friction (reducing power loss), zero stick-slip forpositional accuracy and excellent chemical resistance and fluidcompatibility, making it ideal for hydraulic applications. TheZurcon® polyurethane material used is specially designed to meetthe rigorous demands of hydraulic and pneumatic sealing systemswith high mechanical strength and excellent wear and tearresistance. Luytex® is a bearing material with extremely high wearresistance and excellent performance under dry and boundarylubrication conditions.