Liebherr has launched the "V-Wall Precision" control system for its HS 845 duty-cycle cranes equipped with diaphragm wall grabbers. In urban foundation construction, constructing deep underground walls for basements requires extreme verticality. Traditional free-hanging grabs are susceptible to tidal forces in the slurry trench and operator-induced pendulum swings when crowdsing (pushing the grab into the soil).
The V-Wall system replaces the standard free-fall winch with an "Active-Tension Crowd Winch." The engineering innovation is the "Strain-Gauge Crown Pulley." This sensor measures the exact line tension and deviation angle of the crowd cable 100 times per second. The ECU utilizes a "Pendulum Damping Algorithm." When the operator lowers the grab, the system calculates the natural swing period of the heavy grab. Instead of a simple brake application, the winch motor dynamically alternates between slight motoring and braking, generating a counter-force that kills the pendulum motion within 2 seconds.
Furthermore, the system features "Auto-Verticality Steering." The grab is equipped with hydraulic steering fins at the bottom. If the crown pulley sensor detects the grab is drifting off-center by more than 10mm, the ECU actuates the steering fins to redirect the grab's cutting edge back to the true vertical plane. This closed-loop crowd control eliminates the need for bulky mechanical guides, increasing trenching speed by 25% while maintaining a verticality tolerance of 1/1000.
