Reliable lubrication for vertical lifting bridge
According to lubrication specialist Klüber, high-performance lubricants played a major role in Pont Jacques Chaban-Delmas vertical-lift bridge project in Bordeaux, France.
When moving parts have to function smoothly under high loads, reliable lubrication is a must. The new Pont Jacques Chaban-Delmas vertical-lift bridge in Bordeaux, France is a case in point. Applying three specialty lubricants to all friction points was necessary to meet the requirements of the project.
The Pont Jacques Chaban-Delmas bridge’s 384-foot long middle section can be lifted to allow large vessels, such as cruise ships, to enter and exit the Atlantic Port of Bordeaux. The bridge takes about 11 minutes to reach its lifting height of 174 feet, which occurs about 120 times per year.
Since the historical centre of Bordeaux is a world heritage site, the bridge had to satisfy not only technical requirements, but also had to fit in aesthetically to meet strict UNESCO criteria for new buildings in historical areas. The strong winds prevailing in the region and the whirling waters of the Garonne presented another challenge.
Designed by architects Lavigne and Cheron, the bridge features four freestanding pylons reaching up 253 feet from their bases and resting on a surface area of 11 times 17 feet each. These pylons support the lifting middle section's full weight of approximately 2,750 tons. This unique project required collaboration from the construction firm, GTM from VINCI Group; the engineering firm NFM Technologies; and a lubrication expert, Klüber Lubrication. Lubricating this extraordinary design with its many moving parts proved a demanding task.
The lifting mechanism of the bridge works like a giant elevator. The counterweights – four metal bars weighing a total of 2,694 tons – run up and down inside the pylons. They are connected to the middle section of the bridge by sets of cables running via pulleys 13 feet in diameter, which are mounted at the top of the pylons. In the bases of the pylons, the cables are wound onto drums. The control centre for operating the motors and winches is situated on one of the river banks.
Following an analysis of the system, Klüber Lubrication recommended three specialty lubricants offering the characteristics needed to optimally satisfy the individual requirements of the numerous friction points involved.
The bearings of the cable drums and the winches required a grease with a very high viscosity – above 1000 mm²/s. Klüberlub BE 41-1501, a special grease for rolling bearings running slowly under heavy loads, was recommended. It is based on a highly viscous mineral oil (ISO VG 1500), lithium special soap and EP/AW additives. To allow for insufficient lubricant supply and ensure emergency lubrication, it contains MoS2 and graphite as solid lubricants.
EXTENDED RELUBRICATION INTERVALS
The moving parts in the lifting mechanism are subject to extremely high loads. Its lubrication must be reliable and failure-proof. Since some of the friction points are hard to access, relubrication intervals needed to be as long as possible. Moreover, as Bordeaux is situated near the Atlantic Ocean, its air is rich in salt, which has a corroding effect and causes lubricants to deteriorate rapidly. Another requirement was to use only a small number of different lubricants to rule out product mix-up and make purchasing and storage less complex.
Accordingly, the tribologists recommended Klüberplex AG 11-462. The lubricant is specifically developed for marine applications and can cope with a salty atmosphere. It is a brushable adhesive white operating and priming lubricant containing an aluminium complex soap, mineral oil and white solid lubricant particles. Klüberplex AG 11-462 is resistant to high loads and offers very good corrosion protection when exposed to sea water, making it a good match for the demands of the vertical-lift bridge. It also offers good adhesion and elevated wear protection at low temperatures due to specially selected solid lubricants and additives. Since the lubricant is white, the need for cleaning the area of application is reduced. Klüberplex AG 11-462 offers numerous uses, such as in gear rim and pinion drives, as well as bearings. The couplings, joints, locking mechanisms and guideways of the lifting middle section are also lubricated with Klüberplex AG 11-462.
SYNTHETIC GEAR OILS
The lubrication of moving components is essential to protect installations against failure, particularly in large applications such as a vertical-lift bridge. Klübersynth GH 6-320, a synthetic high-temperature gear oil based on polyglycol, was utilized in the bridge’s gearboxes. It offers high resistance to scuffing and micropitting, as well as very good wear protection to prevent premature bearing failure. Thanks to the excellent aging and oxidation resistance of its synthetic base oil, Klübersynth GH 6-320 attains a much longer service life than mineral oil-based lubricants, leading to longer service intervals. The optimized friction behaviour of the polyglycol base oil reduces power loss and improves gear efficiency. Its excellent viscosity-temperature behaviour also supports the formation of a sufficient lubricant film at elevated or high temperatures. Klübersynth GH 6-320 also has a wide service temperature range.
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