Jack-up of four container cranes

The upgrade involved jacking up the cranes by 4m using the Mega Jack 800, skidding the landside bogies to change the track center distance from 30.54m to 30m, and transporting the cranes to and from the jacking location using winches to pull them along the existing rail tracks.

The cranes were relocated from the Port of Zeebrugge to the Port of Antwerp and needed to be upgraded in preparation for when higher vessels arrived at the Port of Antwerp. The first phase of the upgrade works involved the jacking of the cranes using the Mega Jack 800.

As the maximum allowable ground bearing pressure on site was 6 t/m2, Mammoet placed three layers of load-spreading mats underneath the Mega Jack 800 jacking system to reduce the ground load to a minimum.

Between the Mega Jack 800 and the beams of the container crane, a 10.5m high support construction was used consisting of Mammoet gantry components. The towers of construction were slightly skewed to allow the loads to be introduced closest to the strong points in the crane. By assembling the Mega Jack 800 in this way, large top beams could be eliminated.

First, the Mega Jack 800 received 25% of the crane’s weight. Afterward, the customer removed bolts, connecting the sill beam/bogies with the upper part of the crane. Once all of the bolts were removed, the whole weight of the crane was transferred to the Mega Jack 800 and the jacking could start.

The crane was jacked-up by 550mm at a time until it reached a height of 4.5m. As the crane was lifted, Mammoet needed to stabilize the bogies. The landside bogies were stabilized with Mammoet’s skidding system, installed to move the landside bogies inwards. The waterside bogie was stabilized by Mammoet using diagonal bracing. A hydraulic jack was used on this bracing so that the bogie could be precisely positioned underneath the crane as the crane was set down on the heightened lower structure.

The landside bogies and sill beam had to be moved 54 cm to the inside of the crane. For this, Mammoet used an SS150 skidding system. On top of the skid beams, a beam with integrated jacks was used. With these jacks, the bogies could be lifted out of their rail tracks. After moving the landside bogies, the client installed the leg extensions. When completed, the crane has lowered again on its bogies.

As the cranes were disconnected from the electrical power during the upgrades, Mammoet used winches to relocate the cranes to and from the jacking location. The set-up consisted of two winches on both sides of the crane; two on one side for pulling, and two on the other side for braking and precise positioning of the cranes above the jacking system. The Mega Jack 800 remained in the same position for all cranes.

The four cranes were upgraded in six weeks, with one crane upgraded each week. It took one week for the mobilization and assembly of equipment and another week for the demobilization of equipment.