Three Gorges Dam Ship Lift Moves 15,500 Tonnes Using Counterweight Balance

The Three Gorges Dam on China's Yangtze River houses the world's largest ship lift, designed to vertically transport vessels across a 113-metre elevation difference. Rather than using traditional step-by-step lock systems that take hours, engineers chose to move ships in a single vertical journey inside a water-filled steel basin. The combined weight of the ship, water, and basin reaches approximately 15,500 tonnes, which is nearly offset by a counterweight system so that motors only handle the small remaining imbalance. A rack-and-pinion mechanism ensures all four corners of the basin rise at identical speeds, preventing water from sloshing, while a nut-and-screw safety system instantly locks the basin if a fault occurs. The dam operates two separate transit solutions side by side — the large ship lift for vessels up to 3,000 tonnes and a smaller express channel for lighter boats — completing each vertical crossing in roughly 40 minutes.