| 摘要 |
An arrangement is described which is used in drilling long holes in earth or rock and which determines the orientation of the axis of a bore crown, which is oblique in relation to the centre line of the borehole, for changing the direction of the borehole. The orientation of the bore crown can be changed by rotating a pipe 1 which is inserted into the bore hole and which with its front end is coupled to the bore crown. The arrangement comprises an essentially cylindrical body 2 which can be introduced into the said pipe 1 and which comprises two parts 2a, 2b which can be rotated relative to each other about the longitudinal axis 3 of the body and can be set in the desired reciprocal position of rotation. One part 2a can be releasably coupled to the said pipe 1, near its inner end coupled to the bore crown, in a predetermined position of rotation about the centre line of the pipe. The second part 2b of the body comprises members for detecting this part's angular position about its longitudinal axis relative to a vertical plane through the longitudinal axis. This detection member comprises a preferably annular water-level 9 arranged in a plane at right angles to the longitudinal axis 3 of the body, and a light source 11 and, cooperating with the latter, a photodetector 12 for generating an output signal when the gas bubble 10 in the water-level 9 assumes a predetermined position in the water-level. <IMAGE> |
