| 摘要 |
<p>The quarrying system is for underwater marl. The latter is first broken up by a machine lowered onto it, after which the pieces of marl are raised. A cutter can be used for the breaking operation, driven by a medium supplied under pressure from a pump above the surface of the water, and there can be another such pump supplying pressure to raise the pieces. Water can be used as the medium, driving a lift pump via a hydraulic motor, or alternatively the marl can be raised by grabs on cranes above the surface.</p> |
