NOVELTY - The rig has a combustion-engine-free drive equipment for performing an operation of a transfer drive of the rig, where the drive equipment comprises an electric motor (M) i.e. drive motor, and an electric control device (S). An energy storage unit (B) stores electric energy for the drive. A boom (3a) is movable in relation to a movable carrier. A rock drilling machine (6) is arranged on the boom. A liquid cooling system (21) is connected with an electric component (K). A control unit (C) controls cooling of the electric component. The cooling system is pre-coolable before starting the drive.    USE - Rock drilling rig for drilling fan-like boreholes in a face of a tunnel and a ceiling and walls of a rock cavern, at planned drilling sites.    ADVANTAGE - The drive equipment includes critical electric components with a smaller rated load, thus decreasing component costs of the drive equipment. The electric components of the drive equipment is monitored by a heat sensor, so that cooling of the components to be monitored is increased on the basis of the detected heat load, where the rig utilizes a component specific cooling control to boost the cooling of each component in response to the temperature rise of the components, thus improving the loadability of a single critical component by the cooling, and hence improving performance of the rig. The critical electric components of the drive equipment can be loaded during that operation of the transfer drive due to liquid cooling, so that long transfer distances can be driven at a higher driving speed, thus improving efficiency of the rig.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method for controlling temperature of drive transmission of a rock drilling rig.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a liquid cooling system cooled by a drilling hydraulic system.    Energy storage unit (B)    Control unit (C)    Electric component (K)    Electric motor (M)    Electric control device (S)    Boom (3a)    Rock drilling machine (6)    Liquid cooling system (21)