Abstract: A rock drilling machine is swingably carried on a pivotable drill boom. The rock drilling machine is fed along a drilling axis in response to a feeding movement applied by the drill boom. A set angle value is fed to a servo control system. During drilling, an actual angle value in the form of the angular position in space of the rock drilling machine is fed to the servo control system. The servo control system governs continuously a positioning motor which positions the rock drilling machine relative to the drill boom in such a way that the actual and set values coincide, thereby causing the rock drilling machine to follow the drilling axis.

Abstract: A rock drilling machine is swingably carried on a pivotable drill boom. The rock drilling machine is fed along a drilling axis in response to a feeding movement applied by the drill boom. A set angle value is fed to a servo control system. During drilling, an actual angle value in the form of the angular position in space of the rock drilling machine is fed to the servo control system. The servo control system governs continuously a positioning motor which positions the rock drilling machine relative to the drill boom in such a way that the actual and set values coincide, thereby causing the rock drilling machine to follow the drilling axis.

Abstract: A servo system is presented for controlling the angular attitude of machine units pivotally mounted on an outlying boom frame. Said system is applicable to rock drilling machines, breakers, loading scoops and forks, working platforms, manipulator booms, and the like. The system includes a directional control valve for governing the positioning motor of the machine unit. Under full working pressure the directional valve in itself provides automatic attitude control of the machine unit. To this end the directional valve is provided with a feedback position, in which the pressure fluid communications to the positioning motor are cut off and furthermore has a syngonous (uniangular) relationship on the one hand to the actual angle value of the machine unit with one of its valve elements and on the other to a selective set angle value with its other valve element.