The "dock-wall working vehicle" is a term in marine engineering (standardized in 1998) referring to mobile, elevating work equipment installed along the walls of a dry dock, primarily used for hull maintenance. Mounted on rails along the dock wall, the unit moves longitudinally via a hydraulic drive system. It features a three-section telescopic boom, a work platform with a maximum load capacity of 400 kg, and a maximum working reach of 50 meters. Its integrated electromechanical-hydraulic system supports dual-position operation, is controlled by a programmable logic controller (PLC), and includes a battery-powered emergency backup system.
This type of equipment was utilized in the 50,000-ton capacity No. 3 Dry Dock at Jiangnan Shipyard, which was designed in 1976. The FW4-23A-400 model employs a hydraulically controlled three-section boom design with a length ranging from 10.7 to 21.4 meters and a travel speed of 30 meters per minute. Research institutes have used ANSYS software to optimize the stress distribution of the slewing mechanism and have implemented synchronous travel control using dual motors. Some units are equipped with proportional directional control valves and feature dual-layer protection-comprising mechanical limiters and counterbalance valves-enabling high-pressure water cleaning operations to be performed before the dock is drained. Additionally, dock-wall working vehicle projects have been successfully delivered internationally; these projects, managed by design institutes acting as general contractors, feature equipment that integrates functions such as programmed control and emergency power systems.
