| 摘要 |
The safety system comprises an extensible screen ( 9 ) reversibly extendable and retractable along the mast ( 3 ) and with a proximal end ( 9 A) fixed to the rotary drive ( 5 ), and a distal end ( 9 D), and the extensible screen enclosing the drill string ( 6 ) for at least a part of its length; a side displacement system ( 8 ) fixed to the mast allowing the longitudinal movement of the rotary drive along the mast and moving the rotary drive in a direction transversal to the mast; a sensor arranged for detecting the position of the distal end ( 9 D) in the longitudinal direction. |
