| 摘要 |
<p>The first of the two housings is fixed by screws to a plate, which in turn is fixed to a box fastened on a feed beam. Both housings have through apertures accommodating the drill string provided with a drilling crown. The first housing has parts which are directed radially inwards for working in conjuction with corresp. radially outward parts on the other housing. The two sets of parts from a bayonet coupling, enabling the housings to be rotatably connected to one another. The two housings have surfaces which together form a slide bearing, and the first housing has an arm supporting a shaft. Likewise, the second housing has an arm which supports a shaft. The two shafts are connected to one another by a hydraulic cylinder which causes the two housings to rotate relatively to each other. Each housing is provided with two tension units in the form of hydraulic cylinders provided with jaws for fixing the drill string relatively to the housings. The jaws can also be used to guide the drill string during drilling.</p> |
