Abstract: A device for setting the direction and/or inclination of an elongated rock drilling apparatus. The actual value of the direction in each of two perpendicular planes is sensed by a rotatable screen having a pattern of parallel opaque lines separated by interspaces. Corresponding set values are set by prepositioning a carrying member on which a second screen is mounted which also has a pattern of lines and interspaces. The elongated rock drilling apparatus and the carrying member are moved in common until the line patterns on the screens form a desired moire pattern.

Abstract: An elongated rock drilling apparatus is swingable by positioning power means. Set values of inclination and direction of the rock drilling apparatus are set by prepositioning a first pendulum device relative to the rock drilling apparatus. According to one aspect of the invention the actual values of the inclination and direction of the rock drilling apparatus in perpendicular directions are sensed by means of said first pendulum device. According to another aspect of the invention the actual values of the inclination and direction of the rock drilling apparatus are sensed by means of a second pendulum device. Means are provided for automatically bringing the rock drilling apparatus to a position in which set and actual values of inclination and direction coincide.