Completed in 1904 along the Trent-Severn Waterway in Ontario, Canada, the Peterborough Lift Lock remains the highest dual-can hydraulic boat lift in the world. Designed by superintending engineer Richard Birdsall Rogers, the lock overcomes a steep 19. 8-meter (65-foot) elevation difference using no external pumps or electrical motors to drive the lifting motion.
Instead, the entire system relies on dynamic hydrostatic balancing and gravity. The mechanism consists of two massive water-filled steel press chambers, known as caissons, mounted on giant cast-steel hydraulic rams connected by a subterranean pipe filled with hydraulic fluid. The system acts like a colossal liquid-fueled seesaw.
When both caissons are locked at their respective upper and lower levels, they hold an equal depth of eight feet of water, perfectly balancing each other. To initiate a lift cycle, the operator stops the upper caisson slightly short of full alignment, allowing one additional foot of water to flow into it from the upper reach. This extra foot adds approximately 144 tons of weight to the upper chamber.
When the valve connecting the two hydraulic rams is opened, gravity forces the heavier upper caisson down, which displaces the hydraulic fluid and forces the lower, lighter caisson smoothly upward. Once the trip is complete, the process reverses seamlessly.