The name of the device is derived from the clamshell-like shape of the grab when closed: two steel jaw plates are driven by hydraulic pressure or wire ropes, which can precisely control the opening and closing angles to form an enclosed space to grab the material.
The typical grab capacity range is 0.5-50 cubic meters, and some super-large equipment can reach more than 100 cubic meters, which is suitable for different engineering needs.
Clamshell Grab Dredgers Working flow
Positioning: The ship is fixed to the operation point by anchoring or dynamic positioning system.
Lower the grab: A crane or boom lowers the grab to the bottom of the water and opens it to a maximum angle (usually 120°-150°).
Excavation & Closure: After the grab is inserted into the material, the hydraulic system drives the jaw plate to close, creating a sealed space to grab dirt, rocks or construction debris.
Lifting & Transfer: The grab is lifted to deck level, rotated to the barge or unloaded in a designated area, and a single work cycle is completed.
