Nantes-based Sogecofa, part of the Mediaco Group, used three Terex all terrain cranes to service the Kembs lock on the Grand Canal of Alsace, France. The lock provides power for a hydroelectric station and needed a gate replacing. A Terex AC 350, an AC 500-2 and an AC 700 were used to move the gate, which was 26m wide, 18m tall and weighed 500t.
The rental firm explained that as the lock gate was surrounded by water positioning the cranes for a coordinated tandem lift was impossible. The Sogecofa team decided that the only way they could lift the gate pieces was with a crane inside the lock. For this they used the Terex AC 700 to lower and position the AC 500-2 inside the lock.
Due to space constraints each section of the gate was lifted by the three cranes. The section had to be turned on its edge prior to being swiveled around for placement on rails located in the lock. Once swiveled and brought to a close radius the load was hoisted by the AC 500-2 crane alone.
The operators of the two cranes on the lock wall had no direct view of the load and received instructions from the head of maneuvers who was assisted by an observer.
The length of each load exceeded the width of the chamber so rotational movements required great precision to avoid any impact which could have halted the entire operation.
The same operation was repeated four times. On the last crane maneuver there was just a 20cm margin remaining between the load and the control building of the lock.
