Open, Bridge! Electro-hydraulic Solutions for Drawbridges

By means of a combination of closed circuit hydraulic systems and drive technology, Bosch Rexroth developed an innovative solution aimed at the requirements of civil markets and of infrastructures based on the use of a compact hydraulic cylinder with integrated servo-hydraulic drives. The Tower Bridge in London and the Dubai Creek in the Emirate are two examples of drawbridges which are already being activated using Rexroth technology.

by Giorgia Stella

Bosch Rexroth introduced a new electro-hydraulic drive system meant for large infrastructural and civil engineering projects, including sluices and drawbridges. The innovative system is characterized by a compact hydraulic cylinder with integrated servo-hydraulic drives. New actuators, particularly, use a closed circuit system: they therefore do not need a large oil storage tank on the premises, which is often a significant factor in civil engineering or industrial projects. This guarantees a further advantage whereby the system may be completely tested before supply, drastically reducing tests and commissioning on the premises. Hydraulic cylinders are also very strong with respect to sudden shocks or external loads, such as those caused by ships, which move within and through the sluices.

The system includes sensors for remote monitoring
“This solution is based on closed-circuit hydraulic systems which have been developed for the offshore market. By combining these systems with our drive technologies, we developed an innovative solution which is targeted for the demands of civil markets and infrastructures”, Ron Van Den Oetelaar, vice president of Bosch Rexroth’s Large Projects business unit, explained. The new system therefore combines technologies tested by six different business units within Bosch Rexroth, among them closed circuit hydraulic cylinders, electric drives, power units and control systems. The latter may be installed separately in dedicated cabinets or integrated with the project’s general operating or control system. Besides, the system may include sensors, which monitor quality, oil temperature and other parameters. This allows users to monitor the system remotely, and also allows predictive maintenance, because the operator may verify the presence of any problems as they arise and program maintenance even outside normal operating hours. Two examples are already functioning in London and Dubai. Among the examples of drawbridges activated by Rexroth technology, a significant case is the Tower Bridge in London: this tilting bridge opens thousands of times each year to allow the passage of vessels with superstructures or high sailing masts, with an opening time of about one minute. Bosch Rexroth designed the drive and control solution for the opening mechanism for the bridge’s sections, which weigh about 1,000 tons. Modern hydraulics also protects the historical structure from damages caused by heavy vehicle traffic: the wedges with hydraulic regulation ensure that all the strengths and vibrations which occur are uniformly dispersed. Another installation by Bosch Rexroth is the Dubai Creek: six lanes with an overall width of 22 metres, 365 metres long, on which about 6,000 vehicles travel during the rush hours. To ensure total security of transit, the electronically controlled hydraulic tide compensation, created by Bosch Rexroth, lifts or lowers access ramps to adapt to the water’s level.