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Tower Bridge Special
Clear passage for tall ships
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Clear passage for tall ships
Tower Bridge in London is probably the most famous bascule bridge in the world. To allow tall ships to pass through, the two halves of the bridge open upwards and outwards. The job entails controlling massive forces - a showcase for hydraulics, which is particularly good at generating and controlling large forces in a small area. So, in 1975, Rexroth supplied the mechanism, when the original steam-hydraulic drive was converted to a modern electro-hydraulic system.
Huge masses and forces
If a large freighter or cruise liner is to be allowed through, the two halves of the bridge swing up to an opening angle of 86° depending on the size of the vessel. This is done by means of large cylinders, which are extended by the high oil pressure in the systems hydraulic circuit. Enormous counter-weights, 29 tonnes of lead and 60 tonnes of iron, keep the lifting force low. If we consider purely the weight of a pivot around which the bridge half swivels as it opens it weighs 25 tonnes then we get an idea of the immense forces at work.
150,000 vehicles and 11,000 pedestrians every day
When the bridge is closed, a massive supporting and interlocking system ensures exceptionally high load bearing capacity after all, 150,000 vehicles and 11,000 pedestrians cross the Thames by this route every day. Apart from several local individual controls, the entire electro-hydraulic system is co-ordinated and monitored by a central electrical control.
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