A rock drilling rig, comprising: a movable carrier; combustion-engine-free drive equipment (1 6) for performing transfer drive of the rock drilling rig, which drive equipment comprises at least one electric drive motor and power transmission members between the drive motor and at least one traction wheel; an electric system comprising at least one energy storage in which electric energy used in the transfer drive can be charged; at least one pressure medium system in which pressure and flow of pressure medium is generated with at least one pump (34, 54) which is driven by at least one electric motor (33, 55) connected to the electric system; at least one boom (3a, 3b) movable relative to the carrier and provided with a rock drilling machine; at least one control unit comprising at least one control strategy for controlling the systems; and wherein the drive motor serves as a generator and a primary brake in long-term downhill driving; and wherein the control unit monitors the electric system and controls the electric energy generated in downhill driving to charge the energy storage; characterized in that the control unit comprises a control strategy according to which it turns at least one pressure medium system on in response to the electric system being insufficient to consume the surplus electric energy generated in the downhill driving, whereby the electric energy consumption can be intentionally increased by means of the pressure medium system, and the control unit comprises a control strategy according to which the control unit controls the speed of downhill driving, taking into account the capability of the systems to consume the electric energy generated in deceleration. a movable carrier; combustion-engine-free drive equipment (1 6) for performing transfer drive of the rock drilling rig, which drive equipment comprises at least one electric drive motor and power transmission members between the drive motor and at least one traction wheel; an electric system comprising at least one energy storage in which electric energy used in the transfer drive can be charged; at least one pressure medium system in which pressure and flow of pressure medium is generated with at least one pump (34, 54) which is driven by at least one electric motor (33, 55) connected to the electric system; at least one boom (3a, 3b) movable relative to the carrier and provided with a rock drilling machine; at least one control unit comprising at least one control strategy for controlling the systems; and wherein the drive motor serves as a generator and a primary brake in long-term downhill driving; and wherein the control unit monitors the electric system and controls the electric energy generated in downhill driving to charge the energy storage; characterized in that the control unit comprises a control strategy according to which it turns at least one pressure medium system on in response to the electric system being insufficient to consume the surplus electric energy generated in the downhill driving, whereby the electric energy consumption can be intentionally increased by means of the pressure medium system, and the control unit comprises a control strategy according to which the control unit controls the speed of downhill driving, taking into account the capability of the systems to consume the electric energy generated in deceleration.