| 摘要 |
An elongated rock drilling apparatus is turnable about two shafts, which are perpendicular to one another. A desired drilling direction is defined by the turning angles of the elongated rock drilling apparatus about these shafts. The invention provides means for setting values of said turning angles and means for sensing actual values thereof. Error signals are formed from the difference between corresponding set values and actual values. The error signals are indicated visually. The elongated rock drilling apparatus is positioned manually until the actual values coincide with the set ones. To advantage, the improved manual positioning means can be used in drill booms having conventional parallel motion means. |
