In the middle 1970’s C. H. Bull Company worked with Rigging International in designing a hydraulic jacking system to raise existing 700 ton container cranes 20 feet so extended leg sections could be added. The container ships added extra levels and the cranes needed to be raised. Adding leg extensions was a lot less expensive than a new container crane. Our system used (8) 200 ton 18” stroke double acting jacks with a central gas powered hydraulic pump controlling the 4 pairs of jacks. They system was used successfully for many years by Rigging International