The Pont de Salzinnes stands as a remarkable masterpiece of Belgian industrial civil engineering from the turn of the 20th century. Designed to accommodate both heavy rail freight and dynamic river traffic along the Sambre, the bridge utilized a vertical lift mechanism driven by high-pressure hydraulic accumulators rather than conventional electric gear trains. Large vertical iron towers housed massive cylindrical counterweights suspended by thick forged-steel wire ropes running over high-diameter sheaves.
To initiate lift, pressurized water was pumped into hydraulic cylinders located at the base of the towers. Instead of lifting the deck directly with raw force, the hydraulic pressure acted upon mechanical multiplying sheaves that adjusted the balance ratio between the heavy bridge deck and its counterweights. By slightly tipping the equilibrium of the system, a relatively small hydraulic pump powered by a modest water turbine could lift hundreds of tons of iron structure cleanly into the air within minutes.
Furthermore, the system employed dynamic water-buffering dashpots at the terminus of its travel, absorbing kinetic energy and preventing catastrophic mechanical shock during sudden stops. This precise balance of hydrostatic pressure and gravimetric counterweighting permitted flawless operational reliability during heavy flood seasons when floating debris rendered hinged swing bridges useless.